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230 Cards in this Set
- Front
- Back
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signal transduction pathway
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-sequence of molar events and chemical reactions that lead to a cellular response, following the receptor's activation by a signal.
-signal, receptor, response -may produce short or long term responses |
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dna chemical composition
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-is a polymer of nucleotides: deoxyribose + phosphate group + nitrogen base (by covalent bonds)
-bases: purines-- adenine and guanine pyrimidines-- cytosine and thymine (by hydrogen bonds) |
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purmidines
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-in nucleic acid
-single rings: cytosine (C), thymine (T), Uracil (U) |
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chargaff's rule
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-the abundance of purines = the abundance of pyrimidines
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autocrine
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-signals affect the same cells that release them
-only in cell |
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element
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substance that cannot be broken down to other substances
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dna functions
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-storage of genetic info-- millions of nucleotides
-precise replication during cell division-- by completing base pairing -susceptibility to mutations-- a change in information -expression of coded information as the phenotype-- nucleotide sequence is transcribed into rna and determines sequence of amino acid in proteins |
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paracrine
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-signals diffuse to and affect nearby cells
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peptides
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-short, 20 or fewer amino acids (some hormones and signaling molecules)
-oligopeptides |
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hormones
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-travel to distant cells
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replication fork
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-at end of each replication bubble
-y shaped region where new dna strands are elongating |
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Purines
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-in nucleic acid
-double rings: Adenine (A), Guanine (G) |
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helicases
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-enzymes that untwist double helix at replication fork
-breaks hydrogen bonds |
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allosteric regulation
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-common mechanism of signal transduction
-change shape in protein as a result of a molecule binding to it |
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single-strand binding protein
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-binds to and stabilizes single-stranded dna until it can be used as a template
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proteins
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-polypeptide
-monomers are amino acids linked to form peptide bonds(by covalent) -amino and carboxylic acid functional group -R group differs in each amino acid H3 N+ - C - COO- |
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topoisomerase
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-corrects "overwinding" ahead of replication forks by breaking, swiveling, and rejoining dna strands
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ligands
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-not metabolized, their binding may expose at an active site on a receptor
-binding is reversible |
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dna polymerases
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-enyzmes that catalyzes the elongation of new dna at replication fork
-most polymerases require primer and dna template strand (adding nucleotide) |
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compound
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consisting of 2 or more elements
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when a single replication fork opens up in one direction, 2 dna strands are
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-antiparallel- the 3 end of one strand is paired with the 5 end of other
-dna replicates in 5-3 direction |
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inhibitor
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-aka antagonist
-can bind in place of normal ligand -closes active site |
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lagging strand
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-to elongate other new stand, dna polymerase must work in direction away from replication fork
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nucleic acids
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-polymers specialized for storage, transmission, and use of genetic information
-DNA and RNA -monomers: nucleotide -complementary binding= Adenine and thymine (A-T), and cytosine and guanine (C-G) |
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okazaki fragments
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-lagging strand is synthesized as series of fragments which are joined together by dna ligase
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cell receptors classified by activity
3 receptors |
-ion receptors
-dimensional receptors -g protein-linked receptors |
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telomeres
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-repetitive sequences at ends of eukaryotic chromosomes
-prevent chromosomes ends from being joined together by dna repair system |
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living things are composed of 6 elements
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-carbon
-nitrogen -hydrogen -oxygen -phosphorus -sulfur |
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telomerase
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-acts as template for telomeric dna sequence
-is lost over time in most cells, but not in continuously dividing cells like bone marrow and gametes |
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ion channel receptors
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-aka gated ion channels
-change their 3-dimensional shape when a ligand binds (acetylcholine receptor) -ie. nervous system |
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cells have 2 major repair mechanisms
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-proofreading-- as dna polymerase adds nucleotides, it has proofreading function and if bases are paired incorrectly, the nucleotide is removed
-mismatch repair-- after replication, other proteins scan for mismatched bases missed in proofreading, and replace them with correct ones |
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nucleotide
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-pentose sugar + N base + phosphate group
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mutations
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-changes in nucleotide sequence of dna that are passed on from 1 cell, or organism, to another
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protein kinase receptors
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-change their shape when ligand bonds
-new shape exposes or activates cytoplasmic domain that has catalytic |
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somatic mutations
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-occur in somatic cells, passed on by mitosis but not to sexually produced offspring
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atomic number
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number of protons
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germ line mutations
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-occur in germ line cells that give rise to gametes. a gamete passes a mutation on at fertilization
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g protein receptors
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-ligands binding to g protein-linked receptors expose a site that can bind to a membrane protein
-signal attaches to receptor transmembrane -changes shape and gets phosphorylated -will activate effector protein and all reactions will happen by phosphorelation |
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mutation are caused in 2 ways:
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-spontaneous mutations-- occur with no outside influence, and are permanent
-induced mutations-- due to an outside agent, a mutagen (ie radiation, cigarettes, or liquor) |
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nucleoside
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- pentose sugar + N base
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signal transduction
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-initiates a cascade of protein interactions-signal can amplified and distributed to cause different responses
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mass number
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total number of protons and neutrons
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transcription
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-copies information from dna sequence (a gene) to complimentary rna sequence
-only in nucleus -needs dna template, nucleosides, and enzyme rna polymerase (rna = u-a, c-g) -final product mRNA |
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second messages
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-intermediary between the receptor and cascade responses
-fight of flight response, epinephrine activates the liver enzyme glycogen phosphorylase -breakdown of glycogen to provide quick energy |
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translation
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-converts rna sequence into amino acid sequence of polypeptide
-in cytosol |
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metabolic pathways
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-product of 1 reaction is a substrate for the next, series of reactions
-first reaction is the commitment step- other reactions then happen in sequence -feedback inhibition the final product acts as a noncompetitive inhibitor or the first enzyme, which shuts down the pathway -energy is stored in chemical bonds and can be released and transformed |
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3 kinds of rna in protein synthesis
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-messenger rna (mRNA)
-ribosomal rna (rRNA) -transfer rna (tRNA) |
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signal cascade
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-enzymes may be either activated or inhibited by other enzymes
-in liver cells, signal cascade begins when epinephrine stimulates g protein-mediated protein kinase pathway |
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messenger rna
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-in transcription--carries copy of dna sequence to site of protein synthesis at ribosome
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ionic bond
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-atom gains or loses one/more electron
-result from electrical attraction of opposite charges -cation -anion -bond is weak, so salts dissolve in water |
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ribosomal rna
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-in translation--catalyzes peptide bonds between amino acids
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signal transduction ends
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-after cell responds
-enzymes convert each transducer back to its inactive precursor -balance between regulating enzymes and signal enzymes determines cell's response |
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transfer rna
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-in translation
-mediates between mRNA and protein--carries amino acids for polypeptide assembly -links information in mRNA codons with specific amino acids -for each amino acid, there is a specific type or species of tRNA -2 key events --tRNAs must read mRNA codons correctly --tRNAs must deliver amino acid corresponding to each codon |
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carbohydrates
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-cho
-sugar molecules -Cn(H2O)n1 -source of energy stored -function of structural molecules give organisms shape ie. store glycogen in plant cellulose -serve as recognition or signaling molecules that trigger specific biological responses -transport stored energy -monomer:simple sugars -> mono saccharides -polymers -> polysaccharides |
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formation of specific rna from a specific dna sequence requires
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-dna template for base pairing
-nucleosides (ATP,GTP,CTP,UTP) (all g. couples ugly) -an rna polymerase enzyme |
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cation
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positive charged ion
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transcription occurs in 3 phases
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-initiation
-elongation -termination -all 3 stages require protein factors that aid in the translation process |
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free energy
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-chemical energy available to do work
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transcription initiation
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-requires promoter that tell rna polymerase where to start trancription and which strand of dna to transcribe
-brings together mRNA, a tRNA with first amino acid, and 2 ribosomal subunits -first, a small ribosomal subunit binds with mRNA and special initiator tRNA -then small subunit moves along mRNA and special initiator tRNA -proteins called initiation factors bring in large subunit that completes translation initiation complex |
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pentoses
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-mono saccharides of cho's
-5 carbon sugars -ribose and deoxyribose are backbones of RNA and DNA |
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elongation transcription
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-make long by adding bases to pre mRNA
-amino acids are added one by one to preceding amino acids -each addition involves proteins called elongation factors and occurs in 3 steps 1. codon recognition 2. peptide bond formation 3. translocation (co., pus, together) |
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5 principles governing metabolic pathways
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1. Chemical transformations occur in a series of intermediate reactions that form a metabolic pathway.
2. Each reaction is catalyzed by a specific enzyme. 3. Most metabolic pathways are similar in all organisms. 4. In eukaryotes, many metabolic pathways occur inside specific organelles. 5. Each metabolic pathway is controlled by enzymes that can be inhibited or activated. |
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transcription termination
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-removal of intron keep exon
-coding regions -termination occurs when stop codon in the mRNA reaches the A site of ribosome -A site accepts a protein called release factor -release factor causes addition of water molecule instead of amino acid -reaction releases polypeptide, and translation assembly then comes apart |
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anion
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negative charged ion
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coding regions
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-sequences of dna molecule that are expressed as proteins
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exergonic reaction
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-release energy
-cell respiration -catabolism - (+) - hydrolysis of ATP - ATP + H20 -> ADP + Pi + free energy |
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hexoses
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-mono saccharides of cho's
-6 carbon sugars -(C6 H12 O6) -include glucose, fructose, mannose, and galactose |
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endergonic reaction
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-requires energy
-active transport -cell movements -anabolism - (-) |
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dna synthesis recipe
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1.dna
2. semi conservative (half from parents) 3.enzymes -3.1-- helicase to untwist dna -3.2-- single strand for binding protein -3.3-- topoisomerase prevents overwinding -3.4-- polymerase adds nucleotides to leading strand and lagging stand (= okaski fragments) ---dna polymerase and ligase (glue) |
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covalent bond
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-formed when 2 atoms share pair of electrons
-hydrogen and hydrogen -carbon atoms have 4 electrons in outer shell-from bonds with 4 other atoms -strongest bond |
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pre-mrna processing steps
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1. 5' cap (or G cap) is added to the 5' end
--it facilitates binding and prevents breakdown by enzymes 2. Poly A tail is added to the 3' end at the end of transcprition --assists in export from nucleus and aids stability |
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redox reactions
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-can also be transferred by transfer of electrons in oxidation-reduction
-Na + Cl (becomes oxidized loses electrons)-> Na+ + Cl- (becomes reduced gains electrons) -transfers of hydrogen atoms involve transfers of electrons -when a molecule loses a hydrogen atom it becomes oxidized -more reduced a molecule is, the more energy is stored in its bonds -coenzyme NAD+ (oxidized) is key electron carrier in redox reactions. NADH (reduced form) |
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polysaccharides
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-starch
-glycogen -cellulose |
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reduction
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-gain of 1 or more electons
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start codon
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-AUG
-initiation signal for translation |
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electronegativity
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-attractive force that atomic force exerts on electrons
-strongest is oxygen |
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stop codon
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-UAA, UAG, UGA
-stop translation and polypeptide is released |
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oxidation
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-loss of 1 or more electons
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silent mutation
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-mutation at position 12 in DNA: A instead of C
-no charge in amino acid sequence |
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proteins
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-polypeptide
-monomers are amino acids linked to form peptide bonds(by covalent) -amino and carboxylic acid functional group -R group differs in each amino acid H3 N+ - C - COO- |
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missense mutation
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-mutation at position 14 in DNA: A instead of T
-amino acid change at position 5; Val instead of Asp |
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oxidative phoshorylation
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-transfers energy from nadh to atp
-couples with of nadh: nadh ->nad+ + H+ + 2e- + energy -with production of atp: energy + adp + p1 -> ATP |
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nonsense mutation
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-mutation at position 5 in DNA: T instead of C
-only 1 amino acid translated: no protein made |
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hydrogen bonds
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-attraction between the E- end of one molecule and E+ hydrogen end of another molecule
-form between water molecules -also give water cohesive strength or cohesion |
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frame-shift mutation
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-mutation by insertion of T between bases 6 and 7 in DNA
-result all amino acid changed beyond point of insertion |
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cellular respiration
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-oxidation occurs in a series of small steps in 3 pathways: glycolysis, pyruvate oxidation, citric acid cycle
-6 sugar, needs energy (2 atp), specific enzyme, 10 reactions, 2 3-carbon pyruvate, produce 2 atp and 2 nadh |
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ribosomes
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-large subunit has 3 tRNA binding sites
1. A site 2. P site 3. E site |
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protein primary structure
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-sequence of amino acids by single peptide bond
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A site
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-(amino acid) site binds with anticodon of charged tRNA
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glycolysis
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-10 reactions
-takes place in cytososol -final product: 2 molecules of pyruvate (pyruvic acid), 2 molecules of ATP, 2 molecules of NADH -in step 5 multiply by 2 -uses 2 atp, produce 4 so net is 2 -produces 4 nadh so net is 4 |
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P site
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-(polypeptide) site is where tRNA adds its amino acid to the growing chain
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van der waals interaction
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hold nonpolar hydrocarbons when close together
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E site
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-(exit) site is where tRNA sits before being released from the ribosome
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pyruvate oxidation
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-in inner membrane of mitochondria
-products: CO2 and acetate; acetate is then bound to CoA -draw diagram |
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regulation of gene expression
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-tightly regulated
-gene expression may be modified to counteract enviromental changes -gene expression may change to alter function in cell -constitutive proteins are actively expressed all the time -inducible genes are expressed only when their proteins are needed by cell |
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protein secondary structure
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-regular, repeated spatial patterns in different regions, resulting from hydrogen bonding
-alpha helix= right handed coil -beta pleated sheet= 2 or more polypeptide chains are extended and aligned |
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strategies to regulate gene expression
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-genes can be regulated at level of transcription
-gene expression begins at promoter where transcription is initiated -selective gene transcription |
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citric acid cycle
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-aka krebs cycle
-in mitochondria -8 reactions, operates twice for every glucose molecule that enters glycolysis -starts with 2 acetyl CoA; acetyl group is oxidized to 2 CO2 -oxaloacetate is regenerated in last step -2 cycles that produce 3 nadh, 2 fadh, 2 atp, and 2 co2 |
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polar covalent bond
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-if atoms have different electonegativities, electrons tend to be near the most attractive atom
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transcription factors
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-regulatory proteins that control whether gene is active
-negative regulation-- repressor protein prevents transcription -positive regulation-- activator protein binds to stimulate transcription |
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respiratory chain
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-nadh is reoxidized to nad+ and O2 is reduced to H2o
-series of redox carrier proteins embedded in inner mitochondrial membrane |
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protein tertiary structure
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-polypeptide chain is bent and folded; results in definitive 3-d shape
-outer surfaces present functional groups that can interact with other molecules |
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2 types of operons
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-inducible systems
-repressible systems |
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electron transport chain
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-nadh is reoxidized to nad+ and O2 is reduced to H2o
-electrons from the oxidation of nadh and fadh2 pass from one carrier to next in the chain -32-34 atp added to glycolysis 36-38 atp produced in mitochondria |
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inducible systems
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-turned on unless needed
-metabolic substrate (inducer) interacts with regulatory protein (repressor); repressor cannot bind and allows transcription -control catabolic pathways- turned on when substrate is available |
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non polar covalent bond
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-if 2 atoms have similar electronegativities, they share electrons equally
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repressible systems
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-turned on unless not needed
-metabolic product (co-repressor) binds to regulatory protein, which then binds to operator and blocks transcription -control anabolic pathways-turned on until product concentration becomes excessive |
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energetics total balance
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-from 1 glucose produce about 36-38 of atp
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regulatory systems
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-host cells that repress invading viral genes
-defense mechanism vs. viruses -one system uses transcription "terminator" proteins that interfere with RNA polymerase -HIV counteracts this negative regulation with Tat (transactivator of transcription), which allows RNA polymerase to transcribe the viral genome |
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protein quaternary structure
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-2 or more polypeptide chains bound together by hydrophobic and ionic interactions, and hydrogen bonds
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prokaryotes
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-conserve energy by making proteins only when needed
-gene regulation is at level of transcription -E. coli must adapt quickly to food supply changes. Glucose or lactose may be present (c. gets eaten) |
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fermentation
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-under anaerobic conditions, nadh is reoxidized by fermentation
-many different types, but all operate to regenerate NAD+ -overall yield of ATP is only 2- the atp made in glycoysis |
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uptake and metabolism of lactose involve important proteins
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-beta-galactosidase-- an enzyme that hydrolyses lactose
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functional groups
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-small groups of atoms with specific chemical properties
-1 biological molecule may contain many functional groups |
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E. coli
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-if grown with glucose but no lactose present, no enzymes for lactose conversion are produced
-if lactose is predominant and glucose is low, E. coli synthesizes all 3 enzymes -if lactose is removed, synthesis stops -a compound that induces protein synthesis is an inducer -gene expression and regulating enzyme activity are 2 ways to regulate a metabolic pathway -uses glucose or lactose as energy source |
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alcoholic fermentation
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-pyruvate is converted to ethanol in 2 steps, with the first releasing of co2
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structural genes
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-specify primary protein structure
-3 structural genes for lactose enzymes 1. adjacent on chromosome 2. share promoter 3. transcribed together -their synthesis is all or none |
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protein denaturation
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-alterations in pH, salt concentration, temperature, or other environmental factors can cause protein to unravel
-loss of protein's native structure -biologically inactive |
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operon
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-gene cluster with a single promoter
-- for the lactose enzymes is lac operon |
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lactic acid fermentation
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-pyruvate is reduced to nadh, forming lactate as an end product, with no release of co2
-no oxygen needed |
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operator
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-short stretch of DNA near the promoter that controls transcription of structural genes
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hydroxyl function
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- R-OH
-polar. hydrogen bonds dissolved in water, enables link to other molecule -ie. ethanol |
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catabolism
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-polysaccharides are hydrolyzed to glucose, which enter glycolysis
-lipids break down to fatty acids and glycerol. fatty acids can be converted to acetyl coa -proteins are hydrolyzed to amino acids that can feed into glycolysis or citric acid cycle |
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prokaryotes
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-without membrane enclosed compartments
-no organelles -no nucleus -enclosed plasma membrane made of phospholipids -dna located in nucleoid -cytoplasm -cell wall -capsule flagellus -smaller than eukaryotic cells |
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anabolism
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-many catabolic pathways can operate in reverse
-gluconegenesis- citric acid cycle and glycolysis intermediates can be reduced to form glucose -acetyl coa can be used to form fattly acids (krebs cycle) -some citric acid intermediates can for nucleic acids |
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peptidoglycans
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-in prokaryotic cells bacteria cell walls
-some rod like shape bacteria have a network of actin-like protein structures to help maintain their shape |
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enzymes
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-organic catalysts are substances that speed up reactions
-all enzymes are proteins but not all proteins are enyzmes -bind to specific substrate by active site -reactants are substrates that bind to specific site on enzyme-the active site |
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eukaryotes
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-have membrane-enclosed compartments called organelles, such as nucleus (dna contained)
-cytoplasm and ribosomes -each organelle plays a specific role in cell functioning -cytoplasm -ribosomes -cytosol -organelles-chloroplasts -cell wall (plants) -capsule |
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aldehyde function
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- R- O=C-H
- C=O group very reactive. important in building molecule and in energy releasing reactions -ie. aldehydes |
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keto function
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- R- O=C - R
-C=O group important in carbohydrates and in energy reaction -ie. ketones |
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mutation
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-any genetic variations
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carboxyl function
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- R- O=C-OH (-COOH)
-acidic. ionizes in living tissues to form -COO- and H+ -keto-carbonyl in C skeleton -aldohyde-carbonyl in end -ie. carboxylic acids (vinegar) |
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binary fission
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-prokaryotes
-dna replication -2 identical daughter cells -cytokenesis |
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capsule
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-in prokaryotic cell
-bacteria have slimy layer in polysaccharide |
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sexual reproduction
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-requires gametes- 2 parents each contribute 1 gamete to offspring
-gametes form by meiosis -gametes and offspring differ genetically from each other and from parents (sex cells) |
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amino function
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- R- H-N-H (-NH2)
-need amino for proteins -ie. amines (glycerine) |
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sulfhydrl fuction
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- R-SH
-stabilizes protein structure -ie. thiols (cystene) |
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somatic cells
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-body cells not specialized for reproduction
-not gametes but is mitosis -each contain 2 sets of chromosomes (homologs) that occur in homologous pair -human somatic cells have 23 pairs of chromosomes |
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ribosomes
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-site of protein synthesis
-occur in both prokaryotic and eurakryotic cell and have similar structure-one larger and one smaller subunit -each subunit consists of ribosomal rna (rRNA) bound to smaller protein molecules |
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mitosis
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-eukaryote cells
-dna replication -stomatic cells -cytokinesis -separate single |
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phosphate function
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- oPOS-
-lipids main in cell -ie. organic phosphate (glycerol phosphate) |
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meiosis
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-eukaryotes
-gametes (sperm + eggs) -results in 1 set of chromosomes in each gamete -2 nuclear divisions but dna is replicated only once -reduce the chromosome number -separate pairs -guarantees variation |
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ribosomes - not membrane-bound organelles
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-in eukaryotes: free in cytoplasm, attached to endoplasmic reticulum, or inside mitochondria and chloroplasts
-in prokaryotic cells, ribosomes floar freely in cytoplasm |
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gametes
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-contain only 1 set of chromosomes- 1 homolog from each pair
-only type of human cells produced by meiosis -reproductive cells |
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methyl function
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- CH3
-methylated -5 methy cytidine -in dna -in cancer treatment |
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haploid cells
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-chromosomes = n
-1 set of homolog chormosomes |
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nucleus
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-in eukaryotic cell
-largest organelle -location of dna and dna replication -site where dna is transcribed to rna then produce proteins -surrounded by 2 membranes that for nuclear envelope for protection -nuclear pores in envelope control movement of molecules between nucleus and cytoplasm -dna combines with proteins to form chromatin in long, thin threads called chromosomes -contains nucleolus, where ribosomes begin to assemble from RNA and proteins |
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fertilization
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-2 haploid gametes (egg and sperm) fuse to form zygote
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macromolecules
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-big molecules
-made up of polymers made up of covalent bonding of monomers -polymers formed and broken down in reactions involving water -condensation and hydrolysis ie. polymer->monomers -carbohydrates-sugars -lipids-fats -protein- amino acids -nucleic acids-nucleotides |
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diploid
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-chromosomes number in zygote = 2n
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endomembrane system
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-in eukaryotic cell
-include nuclear envelope -endoplasmic reticulum -golgi appartus -lysosomes -tiny membrane surrounded vesicles shuttle substances between the various compartments as well as to plasma membrane |
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essence of sexual reproduction
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-allows random selection of half diploid chromosomes in set
-this forms haploid gamete that fuses with another male diploid cell -no 2 individuals have exactly the same genetic makeup |
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glycogen (polysaccharides)
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-highly branched polymer of glucose
-main energy of glucose |
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cell division 4 events
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-reproductive signal- to initiate cell division
-replication of dna -segregation- distribution of dna into 2 new cells -cytokinesis- division of cytoplasm and separation of 2 new cells |
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endoplasmic reticulum
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-network of interconnected membranes in cytoplasm with large surface area
- 2 distinct regions 1. smooth ER- lack ribosomes 2. rough ER- has ribosomes studding its surface |
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prokaryotic cell division
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-have 1 chromosome, single molecule of dna-usually circular
-2 important regions in reproduction: -ori- where replication starts -ter- where replication ends |
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cellulose (polysaacharides)
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-most abundant carbon containing biological compound on earth
-glucose+glucose,etc.+ branches of glucose -store energy of plants -cant digest by humans but cows can |
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cytokinesis
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-begins after chromosome segregation by pinching in of the plasma membrane
-as membrane pinches in, new cell wall materials are synthesized resulting in separation of 2 cells |
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smooth er
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-synthesizes lipids and steroids for hormonal reproduction
-metabolizes carbohydrates for energy -detoxifies poisons -stores calcium for electronegativity exchange -glycogen degradation site for energy in liver and muscles |
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eukaryotic cell division
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-eukaryotic cells divide by mitosis followed by cytokinesis
-replication of dna occurs as long strands are threaded through replication complexes -dna replication only occurs during a specific stage of the cell cycle -in segregation of dna after cell division, one copy of each chromosome ends up in each of the 2 new cells -mitosis segregates chromosomes into 2 new nuclei- the cytoskeleton is involved in the process -the process in plant cells(which have cell walls) is different than in animal cell (which do not have cell )walls |
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lipids
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-fats- hydrophobic because of nonpolar covalent bonds
-when close together, weak but additive van der waals interaction hold them together -hydro carbons, -made up of carbon,oxygen,hydrogen -function to protect organs and energy -dehydration is synthesis of fat -vary in length and number and locations of double bonds -saturated and unsaturated fatty acids |
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phases of cell cycle
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-mitotic phase (mitosis and cytokinesis)
-interphase (cell growth and copying of chromosomes in preparation of cell division) about 90% of the cell cycle, subphases: -g1, s, g2 -cell growth during all 3 phases ,but chromosomes are duplicated only during s phase (synthesis) |
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rough er
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-has bound ribosomes with secrete glycoproteins (-proteins and cho's)
-distributes transport vesicles, proteins surrounded by membranes -membrane factory for the cell |
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5 phases of mitosis
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-prophase
-prometaphase -metaphase -anaphase -telophase |
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saturated fatty acids
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-bad fat
-maximum number of hydrogen atoms possible and no double bonds (all single bonds) -solid in room temp |
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during interphase
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-the nuclear envelope and nucleolus are visible
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golgi apparatus
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-consists of flattened membranous sacs called cristernae
-shipping and receiving center |
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3 structures appear in prophase
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-condensed chromosomes, centrosome, spindle
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unsaturated fats
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-good fat
-have 1 or more double bonds -liquid in room temp |
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during prometaphase
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-nuclear envelop breaks down
-chromosomes consisting of 2 chromatids attach to kinetochore microtubules |
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fuctions of golgi appartus
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-modifies products of er
-manufactures certain macromolecules (polysaccharides in plants) for energy and structure -sorts and packages materials into transport vesicles |
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during metaphase
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-chromosomes line up at the midline of cell
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tryglycerides
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-need 1 glycerol and 3 fatty acids
-need 3 condensations reactions |
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during anaphase
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-separation of sister chromatids happens
-after separation, they move to opposite ends of spindle and are referred to as daughter chromosomes |
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cell junctions
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-specialized structures that protude form adjacent cells and glue them together
- 3 structures: tight junctions, desmosomes, and gap junctions |
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telophase
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-occurs after chromosomes separate
-spindle breaks down -chromosomes uncoil -nuclear envelope and nucleoli appear -2 daughter nuclei are formed with identical genetic information -cytokinesis is well underway by late telophase |
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lysosomes
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-primary lysosomes originate from golgi apparatus
-contain digestive enzymes and are the site where macromolecules are hydrolyzed into monomers for energy -carry waste out |
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after cytokenesis
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-each daughter cell contains all components of complete cell
-chromosomes are precisely distributed -orientation of cell division is important to development, but organelles are not always evenly distributed |
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lipids are hydrophobic molecule
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-fatty acids are amphipathic; they have hydophillic end and a hydrophobic tail
-make phospholipid |
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mitrochondria
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-in eukaryotes, molecules are first broken down in cytosol
-partially digested molecules enter mitochondria, here chemical energy is converted to energy rich ATP -cells that require a lot of energy often has more mitochondria ie. heart -2 membranes: outer-porous and inner-extensive folds called cristae to increase surface area for energy production -fluid filled matrix inside the inner membrane contains enzymes, dna and ribosmes |
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karotype
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-ordered display of pairs of chromosomes from a cell
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phospholipid
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-2 fatty acids and phosphate compound
-bound together by glycerol and choline -make cell membranes -in aqueous enviroment they form bilayer -nonpolar,hydophobic tail pack together and phosphate-containing head face outward when interact with water -form phospholipid bilayer structure |
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plastids
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-plant and algae cells contain plastids that can differentiate into organelles- some are used for storage
-chloroplasts contain chlorophyll and is site of photosynthesis -photosynthesis converts light energy into chemical energy |
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sex chromosomes
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- called x and y
-human females of homologous pair of x chromosomes (xx) -human males have one x and one y (xy) -each pair include one chromosome from each parent -46 chromosomes in human somatic cell are 2 sets of 23: one set from the mother and 1 from the father -diploid cell (2n) has 2 sets of chromosomes -for humans diploid number is 46 (2n = 46) |
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protein monomers
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-amino acids
-amino and carboxylic acid functional group -R group differs in each amino acid H3 N+ - C - COO- -20 different |
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autosomes
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-22 pairs of chromosomes that do not determine sex
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other organelles in eukaryotes
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-specialized functions
-peroxisomes collect and break down toxic by-products of metabolism, such as H2O2, using specialized enzymes -scavengers of bad stuff -gloxysomes found only in plants are where lipids are converted to carbohydrates for growth |
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function of meiosis
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-reduce the chromosome number from diploid to haploid
-ensure that each haploid has complete set of chromosomes -generate diversity among products |
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functions of proteins
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-enzymes = catalytic protein
-defensive proteins = antibodies -hormonal and regulatory proteins= control physical processes -receptor proteins= receive and respond to molecular signals -storage proteins= store amino acids -structural proteins- physical stability and movement (muscles) -transport proteins = carry substances (hemoglobin->oxygen) -genetic regulatory proteins= regulate when,how, and to what extent a gene is expressed |
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in meiosis I
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-reduces chromosome number
-homologous pairs of chromosomes come together and line up along their entire lengths |
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vacuoles
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-in eukaryotic cells
-in plants and fungi |
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after metaphase I
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-homologous chromosome pairs separate, but individual chromosomes made up of 2 sister chromatids remain together
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function of vacuole
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1. storage of waste products and toxic compounds; some may deter herbivores
2.structure for plant cells-water enters vacuole by osmosis, creating turgor pressure 3. reproduction: vacuoles in flowers and fruits contain pigments whose colors attract pollinators and aid seed dispersal 4. catabolism-digestive enzymes in seeds' vacuoles hydrolyze stored food for early growth |
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during meiosis II
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-sister chromatids separate, which is not proceeded by dna replication
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functions of cytoskeleton
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-supports and maintains cell shape
-holds organelles in position -moves organelles -involved in cytoplasmic streaming -interacts with extracellular structures to anchor cell in place |
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products of meiosis 1 & 2
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- 4 cells with a haploid number of chromosomes
-these 4 cells are not genetically identical -2 processes may occur: crossing over and independent assortment |
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3 components of cytoskeleton
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-microfilaments
-intermediate -microtubules |
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crossing over
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-in meiosis
-an exchange of genetic material that occurs at chiasma -results in recombinant chromatids and increase genetic variability of products |
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microfilaments
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-in cytoskeleton
-help cell or parts of cell to move -determine cell shape -made from actin-protein -filaments can be made shorter or longer |
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in mieosis prophase I
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-may last a long time
-in human males: prophase I lasts about 1 week, and 1 month for entire meitoic cycle -in human females: prophase l begins before birth, and ends up to decades later during monthly ovarian cycle |
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intermediate filaments
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-in cytoskeleton
-50 different kind -have tough ropelike protein assemblages, more permanent than other filaments and do not show dynamic instability -anchor cell structures in place -resist tension, maintain rigidity -stronger than micromolecules than microfilaments -make tissue |
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independent assortment
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-during anaphase I allows for chance combinations and genetic diversity
-after homologous chromosomes line up at metaphase I, it is a matter of chance which member of a pair goes to which daughter cell -the more chromosomes involved , the more combinations possible |
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microtubules
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-in cytoskeleton
-largest diameter components, -2 roles: 1. form rigid internal skeleton for some cells or regions 2. act as a framework for motor proteins to move structures in cell -pathways for substances to move-road structure of cell -line moveable cell appendages -cilia- short, usually many present, move with stiff power stroke and flexible recovery stroke -flagella- longer usually one or two present, movement is snakelike |
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nondisjunction
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-meiotic errors
-homologous pair fail to separate at anaphase I- sister chromatids fail to separate, or homologus chromosomes may not remain together -either results in aneuoloidy- chromosomes lacking or present in excess |
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extracellular structures
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-allow cells to communicate with external environment
-secreted to outside of plasma membrane -interacting -in eukaryotes, these structures have 2 components: 1.prominent fibrous macromolecule 2. gel-like medium with fibers embedded -plant cell wall-semi rigid structure outside the plasma membrane (steady shape) -fibrous components is the cellulose (cho's, polysaccharides, glucose) -gel like matrix contains cross linked polysaccharides and proteins |
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polyploidy
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-nondisjuction
-organisms with triploid (3n), tetraploid (4n), and even higher levels called polyploid -this can occur through an extra round of dna duplication before meiosis II -occurs naturally in some species, and can be desirable in plants |
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extracellular matrices
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-in animal cells
-holds cells together in tissues -contribute to physical properties of cartilage, skin, and other tissues -filter materials -orient cell movement during growth and repair |
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biological membrane
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-general structure of membranes is known as fluid mosaic model
-phospholipids form bilayer which is like a lake in which variety of proteins float -2 regions: hydrophillic regions- electrically charged heads that associate with water molecules hydrophobic regions-nonpolar fatty acid tails that do not dissolve in water -may differ in lipid composition as there are many types of phospholipids -differ in fatty acid chain length, degree of saturation, kinds of polar groups present |
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2 important factors in biological membrane fluidity:
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-lipid composition-types of fatty acids can increase or decrease fluidity
-temperature-membrane fluidity decreases in colder conditions |
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biological membranes contains proteins
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-peripheral membrane proteins lack hydrophobic groups and are not embedded in bilayer
-integral membrane proteins are partly embedded in bilayer -anchored membrane protein- have lipid components that anchor them in bilayer -transmembrane protein- extend through the bilayer on both sides |
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plasma biological membranes
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-carbohydrates located on outher membrane serve as recognition sites
-glycolipid- carbohydrate bonded to lipid -glycoprotein- carbohydrate bonded to protein |
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selective permeability
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-biological membrane allow some substances, and not others, to pass.
-passive transport does not require energy -active transport- requires energy |
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passive transport
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No atp required. 2 types of diffusion
-simple diffusion -facilitated diffusion through channel proteins or aided by carrier proteins |
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speed of diffusion depends on
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-diameter of molecules- smaller molecules diffuse faster
-temperature of the solution-higher temperatures lead to faster diffusion -concentration gradient the greater the concentration, the faster a substance will diffuse -for equilibrium isotonic solution in animal cell |
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diffusion
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-higher concentration inside the cell causes the solute to diffuse out, and a higher concentration outside causes solute to diffuse in, for many molecules
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osmosis
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-diffusion of water across membranes
-depends on concentration of solute molecules on either side of membrane -water passes through special membrane channels -if not specific cell will fill and burst |
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when comparing 2 solutions separated by a membrane
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-hypertonic solution has higher solute concentration on outside (lysed or turgid normal in plants
-isotonic solutions have equal solute concentrations on outside (normal in animal or flacid) -hypotonic solution has lower solute concentration (shriveled or plasmolyzed) |
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channel proteins
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-aids diffusion
-intergral membrane that form channels across the membrane -substances can also bind to carrier proteins to speed up diffusion -no atp |
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aquaporins
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-water crosses membranes through specific channels
-no atp -allow large amount of water to move against its concentration gradient -may hitchhike with ions such as NA+ as they pass through channels |
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active transport
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-requries energy to move substances against their concentration gradient
-energy source ATP -substances move in direction of cell's needs, usually by means of specific carrier protein |
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2 types of active transport
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1. primary active transport involves hydrolysis of ATP for energy
2. secondary active transport uses energy from ion concentration gradient, or an electrical gradient |
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sodium-potassium (Na+ -K+) pump
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-active transport
-an intergral membrane protein that pumps Na+ out of cell and K+ in -one molecule of ATP moves 2 K+ and 3 Na+ ions -remember illustration |
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endocytosis 3 types
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-moves material in cell through vesicle
1.phagocytosis- cellular eating 2. pinocytosis- cellular drinking 3. receptor-mediated endocytosis |
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exocytosis
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-moves materials out of cell in vesicles
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lac operon
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-inducible
-needs 1. bacteria (e.coli) 2. DNA from bacteria 3.mRNA 4. lactose [galactose and glucose (inducer)] 5.repressor -when glucose is present repressor is blocking enzyme production -when lactose is present repressor deactivated and transcription will happen (beta galactosidase) -final poduct 3 enzymes (all or nothing) |
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determination
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-sets the fate of cell
-influenced by changes in gene expression as well as external environment |
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differentiation
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-process by which different types of cell arise
-actual changes in biochemisty, structure, and function that result in cell of different types |
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morphogenesis
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-organization and spatial distribution of differentiated cells
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growth
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-increase in body size by cell division and cell expansion
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totipotent
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-able to become any cell
-determination is followed by differentiation but under certain condition a cell can become undetermined again |
