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64 Cards in this Set
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phylogeny |
evolutionary family tree; three domains: archaea, bacteria, eukaryota |
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problem of exchange |
surface area:volume ratio decreases as volume increases, which limits necessary exchange across membrane so cells change shape (often "flat") |
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problem of concentration/diffusion |
diffusion is inherently slow and non-directional, and concentration gradients are needed for energy (i.e. the case of Na+/K+) which is difficult in large cells (solute/volume) to accelerate reactions --> cells are compartmentalized to make life fast enough and increase concentration within organelles, but this costs energy to build membranes (endergonic) |
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ribosomes |
complex of RNA + proteins used to synthesize proteins; floats in cytoplasm then attaches to rough ER |
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rough ER |
contains receptors for entry of selected proteins; network of branching sacs with ribosomes associated for lipid synthesis |
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Golgi apparatus |
receptors for products of ER, made of flattened cisternae; used for protein processing (i.e. glycosylation) |
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glycosylation |
attachment of glycans (carbohydrates) to functional group of another macromolecule i.e. lipids or proteins |
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smooth ER |
network of branchign sacs & enzymes for synthesizing phospholipids |
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peroxisomes |
contains transporters for selected macromolecules and enzymes that catalyze oxidation reactions --> processing of fatty acids |
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lysosomes |
contains proton pumps and inside acid hydrolases which catalyze hydrolysis reactions --> digestion and recycling |
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vacuoles |
varies (pigments, oil, carbs, H20, toxins) for various storage purposes |
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mitochondria |
double membrane; inside are enzymes that catalyze oxidation-reduction reactions (ATP synthesis) |
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chloroplasts |
double membrane plus membrane bound sacs in interior, contains enzymes that catalyze redox reactions to produce ATP and sugars via photosynthesis |
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cytoskeleton |
no membrane; actin filaments, intermediate filaments, and microtubules; gives structural support, movement of materials |
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plasma membrane |
single membrane with transport/receptor proteins; selective permeability to maintain intracellular environment |
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cell wall |
no membrane, carbohydrate fibers running through carb or protein matrix |
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protein "address label" |
sequence of amino acids, often near the N or C-terminus, that binds with receptor proteins at destination (R-group interactions) |
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two modes of protein transport |
non-directional (diffusion of soluble proteins) and directional (secretory pathway; uses cytoskeleton) |
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vesicle |
small, watery bag surrounded by phospholipid bilayer |
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chaperone protein |
proteins within rough ER and cytoplasm (for ribosomes) to create proper R-group interactions |
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endosome |
membrane bound vesicle created from the folding in of the plasma membrane; used to bring foreign objects to lysosomes for degradation |
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microtuble |
hollow tube formed from tubulin dimers (proteins); motor proteins kinesin and dynein |
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microfilament |
double helix of actin monomers (proteins); gives cells shape; motor protein myosin |
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intermediate filaments |
strong fiber composed of intermediate proteins; gives nucleus structure |
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microtubule/microfilament dynamics |
one side is more conducive to adding proteins (+ side) so there is net movement of micrtobulues/microfilaments; takes energy since it's anabolic (GTP or ATP); ex. kinesin carries vesicles from ER --> Golgi --> plasma membrane (some motor proteins move from + end to - end) |
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cilia/flagella movement |
composed of microtubules that are moved by dynein motor proteins; 9 + 2 arrangement of microtubule; cilia/flagella move when microtublules slide past one another |
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movement of cell |
microfilaments are anchored to plasma membrane, so + - growth makes cells move |
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muscle movement |
tropomyosin covers myosin binding sites until Ca+2 is present, which allows for troponin to bind and exposes myosin binding sites; ATP allows for movement of motor proteins along actin to "flex" muscle |
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4 categories of cell-cell connections |
1. tight junctions* 2. adherens junction 3. desmosomes* 4. gap junction |
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tight junctions |
cells linked by membrane proteins to form a waterproof barrier (used in bladder, intestine, etc.) |
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desmosomes |
cells loosely linked by proteins attached to intermediate filaments but can resist sheer forces; used in "stress" layers i.e. skin and muscle (transmembrane proteins that "hook" into each other) |
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extracellular matrix |
fiber are proteins excreted by cells; cells hang onto membrane with transmembrane proteins; sugars are also part of extracellular matrix |
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membrane-permeable cell signals |
small nonpolar signaling molecules (i.e. steroids) pass through cell membrane and bind to receptor protein, which changes shape to activate cell (i.e. turn on gene production) |
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membrane-impermeable cell signals |
nonpolar molecule binds to transmembrane receptor protein with polar/charged R-groups, which changes shape (R-group) and activates cell via signal transduction |
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G-protein coupled receptor |
ligand binds to receptor which phosphorylates G protein (goes from GDP to GTP) which can now bind to enzyme to change ATP to cAMP |
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receptor kinase |
kinase is phosphorylated and binds to enzyme; all enzymes that add phosphate are kinase |
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Gap 1 |
growth; cell starts at 1/2 volume; prepares for DNA synthesis, ER, mitochondria, peroxosomes, membrane all grow; needs nucleotides and energy for S phase |
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G0 |
cell not progressing through cycle; most cells are in G0 (neurons are permanently after puberty) |
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S Phase |
synthesis, DNA replication; mitochondria are semi-autonomous but they also replicate |
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Gap 2 |
growth; preparation for mitosis |
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prophase |
chromosomes condense from chromatin fibers; centrosomes radiate microtubules (break original structure) and migrate to poles to make mitotic spindle |
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prometaphase |
microtubules of mitotic spindle attach to chromosomes |
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metaphase |
chromosomes align in center of the cell |
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anaphase |
sister chromatids separate and travel to opposite poles (centromere splits) |
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telophase |
nuclear envelope reforms and chromosomes decondense |
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anaphase dynamics |
motor proteins attached to kinetochore walk towards the minus end of the microtubule as the + end disassembles into tubulin subunits |
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cytokinesis (telophase) |
microfilaments responsible for cell division; myosin proteins squeeze with actin, create contractile ring |
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spindle assembly checkpoint |
cell will enter anaphase if all chromosomes are attached to mitotic spindle |
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DNA replication checkpoint |
at end of G2, cell will enter mitosis if chromosome replication is successful and no DNA damage |
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chromosome |
compacted chromatin |
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chromatin |
DNA packaged around a histone (protein) |
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DNA damage checkpoint |
enter S phase if nutrients are sufficient, growth factors (signals from other cells) are present, cell size is adequate, DNA is undamaged |
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cell "switches" |
Cyclins bind to and activate cyclin-dependent kinases to control progression through thecell cycle; CDKs phosphorylatetarget proteins involved in promoting cell division |
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semi-conservative replication |
the double helix in each sister chromatid contains one new strand of DNA and one old strand of DNA |
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directional replication |
DNA polymerase moves 3' to 5' along old strand to synthesize new strand 5' to 3' |
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helicase |
enzyme that separates DNA strands in double helix |
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topoisomerase |
enzyme that relieves twisting forces |
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Okazaki fragments |
on lagging strand, DNA is replicated in fragments because of 3' to 5' directionality; RNA primase is continually added in replication; DNA polymerase then replaces ribonucelotides with deoxyribonucleotides and DNA ligase closes gap in sugar-phosphate backbone |
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replication bubble/replication forks |
directionality means that DNA synthesis creates many "bubbles" along the strand of DNA where synthesis is happening in two directions |
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benign tumor |
cells continue to divide, but they aren't invasive |
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malignant tumor |
cells divide and spread to adjacent/distant tissues through lymphatic vessels and blood vessels |
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mestastasis |
cell detachment (eliminate protein which breaks junctions via signaling) and cell movement via lymphatic vessels/blood vessels to other tissues |
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light microscope vs. electron microscope |
light electron uses light (photons) to view structures larger than a wavelength of light, so we can see large structures but can't identify them. electron microscopes allow for visualization of anything larger than an electron, so better resolution and smaller structures (but they must be dead) |
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replication bubble vs. replication fork |
replication fork is created by unwinding (helicase/topoisomerase) of DNA. replication bubble is composed of two forks and it gets bigger over time |