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51 Cards in this Set
- Front
- Back
gap junction |
cell signaling: b.t cells next to one another |
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local signaling (3) |
cells in a multicellular organism communicate by chemical messengers animal cells communicate by direct contact or cell-cell recognition e.g. synaptic signaling |
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local regulators |
messenger molecules that travel only short distances |
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paracrine signaling |
short distance communication cell secretes material in close proximity to other cells |
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synaptic signaling |
short distance communication neurotransmitter travels across a synapse |
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hormone signaling |
long distance communication travels into blood stream and binds to receptors *ability of a cell to respond to a signal depends on whether or not it has a receptor specific to that signal |
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three stages of cell signaling |
1) reception: signaling molecule binds to the receptor 2) transduction: signal is converted into an intracellular response 3) response: the action that happens |
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ligand |
molecules that bind to a specific molecule |
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conformational change |
shape change that leads to signal transduction |
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ligand-gated ion channel |
when a signal molecule binds as a ligand to the receptor, conformational change, channel opens, gate allows certain ions to pass through. once ligand disconnects, gate closes. |
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fight or flight response |
lungs: relaxes muscle cells, more oxygen to blood heart: beats faster -> everything moves faster throughout bloodstream liver: releases glucose into blood |
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G protein-coupled receptor |
adrenaline/epinephrine binds to receptor, signals molecules release of glucose is the response (glycogen broken down) |
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insulin and glucose |
insulin binds to insulin receptor, triggers cascade of phosphorylations one outcome is that vesicles containing glucose transporters are moved to cell surface; glucose enters the cell glucose is converted to glycogen |
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intracellular receptors |
*not all signaling molecules are hydrophilic (some are hydrophobic and can go directly through membrane)
receptors that are inside the cell can then bind to the hydrophobic molecules
e.g. testosterone (steroid) |
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endergonic rxns |
require energy, yield products rich in potential energy e.g. photosynthesis |
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exergonic rxns |
release energy, incr kinetic energy (break chem bonds) |
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hydrolysis of ATP |
ATP + H2O -> ADP + Pi exergonic, spontaneous energy coupling to drive chem rxns |
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sucrose + H2O -> glucose + fructose |
exergonic, but not spontaneous at a high enough rate need enzymes to catalyze rxn (e.g. sucrase) |
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enzymes |
dG unaffected, rate affected, activation energy decr highly specific; active site where enzyme interacts with its substrate |
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induced fit (5) |
a change in protein structure that the substrate causes 1) enzyme is available with empty active site 2) substrate binds to enzyme with induced fit 3) substrate is converted to products 4) products are released |
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competitive vs noncompetitive inhibition |
competitive: blocks substrate binding noncompetitive: changes shape elsewhere so that substrate cannot bind |
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allosteric enzyme regulation |
molecule binds on another active site and causes a shape change (can be either activators or inhibitors) |
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feedback inhibition |
enzyme #2 (product) can feedback info into enzyme #1 (reactant) and stop process when no more porduct is needed |
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mitochondria, its parts (6) |
responsible for carrying out cellular respiration outer & inner membrane, intermembranous space matrix: inside cavity of mitochindrion cristae: folds that incr surface area of matrix |
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cellular respiration (4) |
glucose + O2 -> CO2 + H2O + ATP occurs in both plants and animals occurs in two places: cytoplasm & mitochondria (starts in cytoplasm & continues in mitochondria) occurs in 3 stages: glycolysis, citric acid/krebs cycle, oxidative phosphorylation (electron transport chain and chemiosmosis) |
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Glycolysis |
Glucose -> pyruvate Pyruvate enters mitochondria and is oxidized to CoA Final products: 2 pyruvate, 2H2O, 2ATP, 2NADH + 2H+ |
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Citric acid cycle |
Occurs in mitochondrial matrix Organic molecules -> CO2, NADH, FADH2, ATP |
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Oxidative phosphorylation |
Occurs in mitochondrial matrix Chemiosmosis: makes ATP; energy storee in the form of H+ ion gradient across membrane is used to drive cellular work electron transport chain: located in inner membrane of mitochondria; final electron acceptor O2 -> H2O ATP synthase |
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ATP synthase |
Protein complex; molecular motor Protons enter, causes motor to spin, creates ATP Composed of many alpha helices |
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Review of cellular respiration steps |
Chem (potential) energy stored in molecules Relocation of electrons released energy stored in organic molecules Electrons transferred from one molecule to another After each transfer, electrons at a lower energy state Energy released at each step, used to make ATP Last electron transfer is to oxygen, forming water |
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Chloroplasts, structure |
Outer membrane, inner membrane, membranous space (like mitochondria) Thylakoids: membrane stacks, where the light rxns of photosynthesis occur |
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Thylakoid membrane |
Sunlight comes in, H2O comes in, O2 is made Generates ATP & NADPH, whi h feeds into calvin cycle |
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Calvin cycle (P) |
Input is CO2, output is glucose & other organic compounds
Takes place in stroma |
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Chlorophyll |
Main pigment molecule Absorbs physical light |
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Photosystem II |
First step in the two photosystems 1) photon of light excites electron in pigment molecule. when electron falls back into ground state, energy gets transferred from one pigment molecule to the next. 2) energy eventually gets transferred to a special pair of chlorophyll molecules in the middle. electrons are bumped to a specialized primary electron acceptor molecule 3) electrons are passed on to the electron transport chain 4) electron hole left behind is replenished by pulling electrons from H2O, leaving behind O2 (chlorophyll molecules are strong electron acceptors) |
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Photosystem I |
Second step in the two photosystems Same as photosystem II, but electron hole is refilled by electrons from the electron transport chain |
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Chromosomes |
DNA wrapped protein, made up of chromatin |
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cell cycle: G0 |
"rested phase", no change happening
Cell waits in g0 until they get the go-ahead |
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cell cycle: G1 |
gap phase #1; wait, grow
Cell checks the Stop and Go signals |
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cell cycle: S |
synthesis of DNA
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cell cycle: G2 |
gap phase #2; checks to see if DNA was duplicated properly; prepares cytoskeleton for cytokinesis (a pair of centrioles move to opposite ends of cell and form spindles)
Cell checks the Stop and Go signals |
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cell cycle: M |
mitosis; divides DNA and cytokinesis
without full chromosome attachment, stop signal is received |
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Mitosis spindle |
a bunch of microtubules that set up a structure that allows chromosomes to align on them and be pulled apart evenly. chromosomes become condensed, gather toward center mitosis spindles attach to sister chromatids |
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Kinetochore
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the actual protein complex that microtubules are attaching to
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Metaphase |
Imaginary metaphase plate at middle of the cell where sister chromatids align exactly in a row |
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Mitosis cont. |
Sister chromatids get pulled apart, daughter chromosomes go to either side Cytoplasm gets indentation (result of microfilaments and other cytoskeletal filaments) Two nuclei reform with exactly the same complement in both of them |
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Evidence for a control system (experiment) |
A factor present in the cytoplasm of the S phase or the M phase controls the progression of the cell cycle |
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Growth factor |
chemical factors that will promote cell growth (e.g. platelet-derived growth factor PDGF gives cell the go signal so cells divide) |
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Physical factors |
Anchorage-dependence: need to be attached to a surface to grow Density-dependent inhibition: when a cell come into contact with other cells, it stops division, forming a monolayer of cells |
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Cancer |
Cancer cells escape cell cycle controls Cancer cells divide rapidly, often in absence of growth factors (RAS protein: activating "go" signals) Growth uninhibited by other cells, tumors form (benign tumors remain at original site, malignant tumors spread to other locations by metastasis) |
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p53 gene
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most frequently altered gene in cancers
tumor suppressor; when mutated, doesn't read stop signals |