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58 Cards in this Set

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  • Back
what is the nucleus?
-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)
what are chromosomes?
-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
what are chromatin?
-1 strand of DNA
-found in this form in the nucleus during interphase
what are chromatid?
-2 strands of DNA connected to each other by a centromere
-1 strand is a replica of the other
-exists only during mitosis
what is the diploid number?
-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
what are autosomes?
-22 out of 23 chromosomal pairs
-they code for non sex related traits
what are the sex chromosomes?
-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)
what is DNA replication?
-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
what is semi-conservative replication?
-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
what is the nucleoplasm?
-a souplike mix containing the enzymes and nucleotides necessary for semi conservative replication
what are histones?
-proteins that the DNA strand wraps around to create chromosomes
what is mitosis?
-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
what is meiosis?
-cell division that only takes place in reproductive cells in order to form gametes.
what is a gamete?
-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
what is the haploid number?
-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
what is a zygote?
-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
what are glycoproteins?
-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
what are antigens?
-markers that identify tissues and cells
what are pumps?
-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
what are receptors?
-proteins in a cell membrane with a specific shape that bind hormones
what do enzymes in a cell membrane do?
-they change particles as they enter the cell
what are the 3 variations of selective permeability?
-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
what are the 3 methods of passive transport?
-diffusion
-facilitated transport (diffusion)
-osmosis
describe diffusion through a cell membrane
-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
what is facilitated transport (also called facilitated diffusion)?
-"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
what is osmosis?
-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
what is osmotic pressure?
-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.
what is filtration?
-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
what are the 3 forms of active transport?
-pumps
-endocytosis
-exocytosis
what are cell membrane pumps?
-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
what is endocytosis?
-taking material into the cell by engulfing it
what are the 3 methods of endocytosis?
-phagocytosis
-pinocytosis
-receptor mediated endocytosis
what is phagocytosis?
-"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
what is pinocytosis?
-"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
what is receptor mediated endocytosis?
-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
what is a phagosome?
-particulate matter enclosed in a vesicle after it has been brought into the cell for phagocytosis
what is a phagolysosome?
-a phagosome that has merged with a lysosome to digest particulate matter
what is exocytosis?
-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
what is the endoplasmic reticulum?
-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
what is the rough endoplasmic reticulum?
-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
what is the smooth endoplasmic reticulum?
-E.R. with no ribosomes attached to its surface
-contains enzymes for lipid synthesis
-transports lipids through the cell
what is the golgi apparatus (or golgi complex)?
-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
what is excision?
-cutting out of certain proteins from a long protein chain
what is glycosylation?
-the addition of sugar to the protein
what is a lysosome?
-small vesicles enclosing destructive hydrolytic enzymes
-digests particulate matter taken in through endocytosis
-used in auto digestion (where certain cells are purposely destroyed)
what are the mitochondria?
-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
what are microfilaments?
-structural proteins that provide support and strength to the cell
-responsible for cell shape
-made of actin and myosin among other things
what are actin and myosin?
-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
what are microtubules?
-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
what are the centrioles?
-2 small cylindrical bodies set at right angles to each other
-made of microtubule aggregations
-initiate spindle formation during prophase
what is transcription?
-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
what is the initiator codon?
-the N-base triplet that signals the beginning of the gene
-ALWAYS TAC (thymine, adenine, cytosine)
what is the triplet code?
-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
what is a code?
-a triplet group on the DNA strand
what is a codon?
-a triplet group on an mRNA strand
-a mirror image of a code
what is an anti-codon?
-a triplet group on a tRNA strand.
-mirror image of the codon, same as the code but with uracil replacing thymine
what is translation?
-the process of using the code on the mRNA to synthesize proteins
-takes place in a ribosome, requires the use of mRNA and tRNA
describe translation
-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!