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58 Cards in this Set
- Front
- Back
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what is the nucleus?
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-the control center of the cell; it regulates all cellular activity
-it contains the hereditary information in the form of DNA -it is responsible for carrying out cell division (mitosis & cytokinesis) |
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what are chromosomes?
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-strands of DNA containing the hereditary information
-composed of the DNA molecule wrapped around proteins called histones -always exist as pairs -they are homologous but not identical -exist either as chromatin or chromatid |
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what are chromatin?
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-1 strand of DNA
-found in this form in the nucleus during interphase |
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what are chromatid?
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-2 strands of DNA connected to each other by a centromere
-1 strand is a replica of the other -exists only during mitosis |
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what is the diploid number?
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-46
-the total number of chromosomes in a normal human cell -23 pairs, with one set of 23 coming from the mother and the other set of 23 coming from the father |
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what are autosomes?
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-22 out of 23 chromosomal pairs
-they code for non sex related traits |
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what are the sex chromosomes?
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-1 out of 23 chromosomal pairs
-determine the sex of a person -female chromosome is XX, male chromosome is XY (the male sex chromosomes are not homologous) |
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what is DNA replication?
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-the precursor to mitosis
-all the chromatin in the nucleus copy themselves (creating chromatid) and await anaphase, where each chromatid will separate, sending 1 copy to each side of the nucleus |
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what is semi-conservative replication?
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-the process of copying DNA before mitosis can start
-binding, stabilizing, and unwinding proteins open up the double stranded DNA molecule -each single strand serves as a bonding template -n bases in the nucleoplasm rebond to each strand resulting in 2 separate double stranded DNA molecules |
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what is the nucleoplasm?
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-a souplike mix containing the enzymes and nucleotides necessary for semi conservative replication
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what are histones?
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-proteins that the DNA strand wraps around to create chromosomes
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what is mitosis?
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-division of a cell
-should produce 2 identical daughter cells -during mitosis, all 46 chromosomes replicate, line up and separate, with each one going to one end of the cell -cytoplasm divides and each new cell has all 46 chromosomes |
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what is meiosis?
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-cell division that only takes place in reproductive cells in order to form gametes.
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what is a gamete?
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-a reproductive cell; either an egg or a sperm
-each only has 1 set of chromosomes, 23 -the male gamete and the female gamete combine to form a zygote |
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what is the haploid number?
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-23
-reproductive cells only have 1 set of chromosomes; they are made with the function of joining another reproductive cell to produce the full set of chromosomes, 46 |
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what is a zygote?
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-the union of a sperm and an egg; each has the haploid number, when they combine they form a diploid cell, with 46 chromosomes
-undergoes rapid mitosis to form millions of diploid cells creating a human being -not like either parent cell; it is the product of 2 sets of info |
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what are glycoproteins?
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-they are inserted into the cell membrane, along with regular proteins
-some span the entire membrane, some only face the intracellular fluid or extracellular fluid -they act as antigens, pumps, receptors, enzymes, and pores |
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what are antigens?
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-markers that identify tissues and cells
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what are pumps?
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-proteins in the cell membrane that moves things through the membrane
-a form of active transport, they need ATP to operate -each pump generates its own ATP |
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what are receptors?
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-proteins in a cell membrane with a specific shape that bind hormones
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what do enzymes in a cell membrane do?
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-they change particles as they enter the cell
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what are the 3 variations of selective permeability?
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-the size of the molecule; if its too big it cant fit through the phospholipid bilayer
-lipid solubility; if a molecule is soluble in lipids, such as O or CO2 it can get in -polarity; non polar molecules diffuse through the bilayer easily |
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what are the 3 methods of passive transport?
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-diffusion
-facilitated transport (diffusion) -osmosis |
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describe diffusion through a cell membrane
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-takes place through protein channels in the cell membrane
-the protein coils and forms a hollow channel that spans the entire cell membrane -the channel has a specific polarity and diameter, allowing only certain ions to diffuse through |
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what is facilitated transport (also called facilitated diffusion)?
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-"helper" proteins (referred to as special carriers) in the cell membrane bind substances and change shape, pulling them into the cell
-the shape of the protein determines what substances can be bound -proteins work to maintain equilibrium between the intracellular and extracellular environments |
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what is osmosis?
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-it is water moving to reach equilibrium
-refers to the diffusion of water ONLY through a cell membrane ONLY. NOTE: the concentration of a solution is always given in terms of the solute. ex: a 10% salt solution, NOT a 90% water solution |
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what is osmotic pressure?
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-when a high concentration of solute attracts water, causing it to move to a higher concentration
-the solute has osmotic pressure, the power to pull water to it. |
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what is filtration?
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-it involves the movement of water, solvent, and solute through the pores of a membrane under pressure
-only the molecules small enough to fit through the pores will be filtered -ex. blood pressure moving through kidney filters out urea, sugar, ions & amino acids |
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what are the 3 forms of active transport?
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-pumps
-endocytosis -exocytosis |
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what are cell membrane pumps?
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-act like carrier proteins but use ATP in order to operate
-they bind substances to be transported, act as an ATPase and hydrolyze ATP as they bring the substances into the cell |
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what is endocytosis?
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-taking material into the cell by engulfing it
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what are the 3 methods of endocytosis?
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-phagocytosis
-pinocytosis -receptor mediated endocytosis |
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what is phagocytosis?
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-"cell eating"
-cytoplasm extends into "arms", called pseudopods, that surround and engulf particulate matter -membrane forms a vesicle around the particle, called a phagosome -the phagosome merges with a lysosome, forming a phagolysosome, which digests particle via lysosome's digestive enzymes |
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what is pinocytosis?
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-"cell drinking"
-cell membrane depresses and fluid flows into the channel that is formed -channel pinches off, forming a vacuole around the fluid (same as a vesicle) -vesicle merges with lysosome and the fluid is digested via lysosome's digestive enzymes |
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what is receptor mediated endocytosis?
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-the method used to bring hormones and other regulatory molecules into a cell
-molecules bind to receptors scattered across the cell membrane's surface -the bound receptors migrate across the membrane to an area lined with the protein clathrin (called the pit) -the pit depresses taking receptors and bound regulators into cell and forms a vesicle around them -receptors may then return to the cell membrane and bind regulatory substances again |
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what is a phagosome?
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-particulate matter enclosed in a vesicle after it has been brought into the cell for phagocytosis
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what is a phagolysosome?
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-a phagosome that has merged with a lysosome to digest particulate matter
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what is exocytosis?
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-the method used to transport substances out of the cell
-vesicles containing substances fuses to the inside of the cell membrane -a pore opens up releasing the contents of the vesicle out through the pore |
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what is the endoplasmic reticulum?
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-a network of membranous tubules filling cytoplasm and connecting the nuclear membrane to the plasma membrane
-may be smooth or rough -transports molecules through the cytoplasm |
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what is the rough endoplasmic reticulum?
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-E.R. that is studded with ribosomes making it look like sandpaper
-the ribosomes synthesize and secrete proteins directly into the E.R. -used for protein transport through the cell |
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what is the smooth endoplasmic reticulum?
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-E.R. with no ribosomes attached to its surface
-contains enzymes for lipid synthesis -transports lipids through the cell |
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what is the golgi apparatus (or golgi complex)?
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-modifies and packages protein secretions through excision and glycosylation
-a stack of membranous sacs formed from the E.R. -packages modified protein in a vesicle to be secreted out of cell by exocytosis |
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what is excision?
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-cutting out of certain proteins from a long protein chain
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what is glycosylation?
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-the addition of sugar to the protein
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what is a lysosome?
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-small vesicles enclosing destructive hydrolytic enzymes
-digests particulate matter taken in through endocytosis -used in auto digestion (where certain cells are purposely destroyed) |
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what are the mitochondria?
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-small sausage like organelles responsible for synthesizing ATP
-composed of a double membrane, the inner folded membrane called the cristae -enzymes inserted into cristae used to make ATP |
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what are microfilaments?
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-structural proteins that provide support and strength to the cell
-responsible for cell shape -made of actin and myosin among other things |
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what are actin and myosin?
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-substances used to create microfilaments
-used in: Amoeboid Movement: pseudopods during phagocytosis Cytokinesis: contracts middle of cell during cytoplasmic division Sliding Filament Mechanism: used for muscle contraction |
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what are microtubules?
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-microscopic hollow tubules composed of tubulin protein
-forms cytoskeleton, mitotic spindle -forms cilia and flagella, which are essential for the movement of sperm and functioning of the "ciliatory escalator" of the respiratory system |
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what are the centrioles?
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-2 small cylindrical bodies set at right angles to each other
-made of microtubule aggregations -initiate spindle formation during prophase |
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what is transcription?
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-copying the sense strand of the DNA to the mRNA.
-instead of using thymine, uracil is paired wherever adenine is present -once the mRNA is copied it is released to go meet a ribosome and be used to create a protein. the DNA may now rebond with the nonsense strand or it may remain open to create more mRNA |
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what is the initiator codon?
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-the N-base triplet that signals the beginning of the gene
-ALWAYS TAC (thymine, adenine, cytosine) |
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what is the triplet code?
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-a chemical coding for different genes
-3 nucleotides in the sense strand code for 1 amino acid, many amino acids are joined together to form proteins, which are used to build all bodily structures -it is a "degenerate" code; small mutations in the triplet code will still yield the same amino acid Ex. AAA, AAT, AAG will all code for the same amino acid |
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what is a code?
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-a triplet group on the DNA strand
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what is a codon?
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-a triplet group on an mRNA strand
-a mirror image of a code |
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what is an anti-codon?
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-a triplet group on a tRNA strand.
-mirror image of the codon, same as the code but with uracil replacing thymine |
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what is translation?
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-the process of using the code on the mRNA to synthesize proteins
-takes place in a ribosome, requires the use of mRNA and tRNA |
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describe translation
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-mRNA leaves nucleus and joins ribosome, where translation will take place and lead to protein synthesis
-tRNA recognizes codon on mRNA via its on anticodon and brings the proper amino acid into the ribosome, the ribosome attaches 2 amino acides together forming a dipeptide -one tRNA leaves, another enters, ribosome attaches the new amino acid to the dipeptide forming tripeptide -this process continues until all the triplet codes on the mRNA strand are read and the appropriate amino acids are connected creating a polypeptide chain = PROTEIN! |
