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64 Cards in this Set

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phylogeny

evolutionary family tree; three domains: archaea, bacteria, eukaryota

problem of exchange

surface area:volume ratio decreases as volume increases, which limits necessary exchange across membrane so cells change shape (often "flat")

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)

ribosomes

complex of RNA + proteins used to synthesize proteins; floats in cytoplasm then attaches to rough ER

rough ER

contains receptors for entry of selected proteins; network of branching sacs with ribosomes associated for lipid synthesis

Golgi apparatus

receptors for products of ER, made of flattened cisternae; used for protein processing (i.e. glycosylation)

glycosylation

attachment of glycans (carbohydrates) to functional group of another macromolecule i.e. lipids or proteins

smooth ER

network of branchign sacs & enzymes for synthesizing phospholipids

peroxisomes

contains transporters for selected macromolecules and enzymes that catalyze oxidation reactions --> processing of fatty acids

lysosomes

contains proton pumps and inside acid hydrolases which catalyze hydrolysis reactions --> digestion and recycling

vacuoles

varies (pigments, oil, carbs, H20, toxins) for various storage purposes

mitochondria

double membrane; inside are enzymes that catalyze oxidation-reduction reactions (ATP synthesis)

chloroplasts

double membrane plus membrane bound sacs in interior, contains enzymes that catalyze redox reactions to produce ATP and sugars via photosynthesis

cytoskeleton

no membrane; actin filaments, intermediate filaments, and microtubules; gives structural support, movement of materials

plasma membrane

single membrane with transport/receptor proteins; selective permeability to maintain intracellular environment

cell wall

no membrane, carbohydrate fibers running through carb or protein matrix

protein "address label"

sequence of amino acids, often near the N or C-terminus, that binds with receptor proteins at destination (R-group interactions)

two modes of protein transport

non-directional (diffusion of soluble proteins) and directional (secretory pathway; uses cytoskeleton)

vesicle

small, watery bag surrounded by phospholipid bilayer

chaperone protein

proteins within rough ER and cytoplasm (for ribosomes) to create proper R-group interactions

endosome

membrane bound vesicle created from the folding in of the plasma membrane; used to bring foreign objects to lysosomes for degradation

microtuble

hollow tube formed from tubulin dimers (proteins); motor proteins kinesin and dynein

microfilament

double helix of actin monomers (proteins); gives cells shape; motor protein myosin

intermediate filaments

strong fiber composed of intermediate proteins; gives nucleus structure

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)

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

movement of cell

microfilaments are anchored to plasma membrane, so + - growth makes cells move

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

4 categories of cell-cell connections

1. tight junctions*


2. adherens junction


3. desmosomes*


4. gap junction

tight junctions

cells linked by membrane proteins to form a waterproof barrier (used in bladder, intestine, etc.)

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)

extracellular matrix

fiber are proteins excreted by cells; cells hang onto membrane with transmembrane proteins; sugars are also part of extracellular matrix

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)

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

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

receptor kinase

kinase is phosphorylated and binds to enzyme; all enzymes that add phosphate are kinase

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

G0

cell not progressing through cycle; most cells are in G0 (neurons are permanently after puberty)

S Phase

synthesis, DNA replication; mitochondria are semi-autonomous but they also replicate

Gap 2

growth; preparation for mitosis

prophase

chromosomes condense from chromatin fibers; centrosomes radiate microtubules (break original structure) and migrate to poles to make mitotic spindle

prometaphase

microtubules of mitotic spindle attach to chromosomes

metaphase

chromosomes align in center of the cell

anaphase

sister chromatids separate and travel to opposite poles (centromere splits)

telophase

nuclear envelope reforms and chromosomes decondense

anaphase dynamics

motor proteins attached to kinetochore walk towards the minus end of the microtubule as the + end disassembles into tubulin subunits

cytokinesis (telophase)

microfilaments responsible for cell division; myosin proteins squeeze with actin, create contractile ring

spindle assembly checkpoint

cell will enter anaphase if all chromosomes are attached to mitotic spindle

DNA replication checkpoint

at end of G2, cell will enter mitosis if chromosome replication is successful and no DNA damage

chromosome

compacted chromatin

chromatin

DNA packaged around a histone (protein)

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

cell "switches"

Cyclins bind to and activate cyclin-dependent kinases to control progression through thecell cycle; CDKs phosphorylatetarget proteins involved in promoting cell division

semi-conservative replication

the double helix in each sister chromatid contains one new strand of DNA and one old strand of DNA



directional replication

DNA polymerase moves 3' to 5' along old strand to synthesize new strand 5' to 3'

helicase

enzyme that separates DNA strands in double helix

topoisomerase

enzyme that relieves twisting forces

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

replication bubble/replication forks

directionality means that DNA synthesis creates many "bubbles" along the strand of DNA where synthesis is happening in two directions

benign tumor

cells continue to divide, but they aren't invasive



malignant tumor

cells divide and spread to adjacent/distant tissues through lymphatic vessels and blood vessels

mestastasis

cell detachment (eliminate protein which breaks junctions via signaling) and cell movement via lymphatic vessels/blood vessels to other tissues

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)

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