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28 terms

Biology 5- Cell Membranes

STUDY
PLAY
membranes (fluid mosaic)
composed of phospholipids + proteins; contain integrins which attach to cytoskeleton to give membrane a stronger framework
diffusion
process in which particles spread out evenly in available space; from high=> low concentration (diffuse down "concentration gradient" until equilibrium)
passive transport
DIFFUSION across membrane with NO ENERGY investment
concentration gradient
ENERGY for DIFFUSION
osmosis
DIFFUSION OF WATER across membrane
tonicity
ABILITY of solution to cause a cell to GAIN/LOSE water;
depends on concentration of solute inside/outside of cell
isotonic concentration
equal on both sides
hypertonic concentration
concentration is greater outside
hypotonic concentration
concentration is less outside
aquaporins (transport proteins)
use FACILITATED DIFFUSION to help substances across membrane (no energy)
hydrophilic tunnel
binds passenger, changes its shape, and releases passenger on the other side; protein is specific for its substrate
active transport
cells expend ATP against their concentration gradient
moving large molecules
material packaged in vesicle that fuses w/ membrane:
1) exocytosis= EXPORT molecules
2) endocytosis= IMPORT substances
endocytosis
IMPORT substances;
1) PHAGOCYTOSIS= engulf particle by wrapping cell membrane around it and forming vacuole
2) PINOCYTOSIS= same, except fluids are taken into small vesicles
3) RECEPTOR-MEDIATED ENDOCYTOSIS= receptors interact with protein, forming a vessicle
energy
CAPACITY to do WORK and CAUSE CHANGE
work
when an object is MOVED against another object
kinetic energy
energy of motion=> transfers motion to other matter
potential energy
energy of object b/c of its location
ex. water behind a dam; chemical energy
chemical reactions
1) EXERGONIC REACTION= RELEASES energy
- ex. cellular respiration
2) ENDERGONIC REACTION= requires INPUT of energy + yields products rich in potential energy
- ex. photosynthesis
metabolism
exergonic + endergonic reactions in living organisms
3 types of work
1) chemical= driving ENDERGONIC reactions
2) transport= pumping SUBSTANCES ACROSS MEMBRANES
3) mechanical= BEATING of CILIA
energy coupling
use of EXERGONIC processes to DRIVE ENDERGONIC processes in order to accomplish work
phosphorylation
hydrolysis of ATP that releases energy by transferring 3rd phosphate from ATP to another molecule
ATP
shuttles CHEMICAL ENERGY and drives CELLULAR WORK; composed of adenine, ribose, 3 phosphate groups; renewable source of energy
energy
energy released in EXERGONIC REACTIONS is used to generate ATP for ENDERGONIC REACTIONS
enzymes
speed up cell's chemical reaction by lowering energy barriers (energy of activation); unique 3-D shape with an ACTIVE SITE where SUBSTRATE binds;
require optimum temperate & optimum pH
cofactors
inorganic enzymes (copper, zinc, iron)
coenzymes
organic enzymes (vitamins)