AP bio chapter 6 and 7 Flashcards
name major components of cell membrane
glycoproteins, glycolipids, phospholipid bilayer, cholesterol, cytoskeleton filaments, integral membrane proteins, peripheral membrane proteins, carbohydrates, fibers of extracellular matrix
glycoproteins
on outside of plasma membrane, compromise protein and carbohydrate chains, membrane carbohydrates covalently bonded to proteins
glycolipid
on extracellular surface of cell membrane, membrane carbohydrates covalently bonded to lipids
phospholipid bilayer
acts as barrier to protect cell against outside components
cholesterol
in between phospholipids, stabilizes cell membrane
cytoskeleton filaments
in the cytoplasmic side of membrane, give cell shape and organize cell parts
integral membrane proteins
within bilayer membranes, penetrates hydrophobic core, helps move molecules across membrane
peripheral membrane proteins
bound to surface of membrane, helps in communication, support, and molecule transfer
carbohydrates
present on extracellular side of membrane (exterior), attached to proteins and form glycoproteins
extracellular matrix fibers
fills space between cells, in extracellular side of membrane (exterior), helps cell attach and communicate with cells
transmembrane protein
integral proteins that span the membrane
carrier protein
transport protein that binds to molecules and change shape to shuttle them across the membrane, undergo subtle change in shape that translocates the solute-binding site across the membrane
transport protein
allow passage of hydrophilic substances across the membrane, specific for substance it moves, can move solutes against their concentration gradient
integrin protein
mediate interactions between cytoskeleton and extracellular matrix
aquaporins
channel proteins that facilitate the passage of water (facilitated diffusion of water)
channel protein
type of transport protein has hydrophilic channel that certain molecules or ions can useas a tunnel
what does cholesterol do in animal cells
restrains movement at warmer temperatures and maintains fluidity by preventing tight packing at cooler temperatures
6 functions of membrane proteins
transport
enzymatic activity
signal transduction
cell-cell recognition
intercellular joining
attachment to cytoskeleton and extracellular matrix
how can a hydrophobic (nonpolar) molecule pass through the cell membrane
can dissolve in the lipid bilayer and pass through membrane rapidly
how can a hydrophilic (polar) molecule pass through the cell membrane
don’t cross through membrane easily, use facilitated diffusion (carrier and channel proteins) (EX. sugar)
how can ions pass through cell membrane
facilitated diffusion (carrier and channel proteins and ion channels)
how can small molecules pass through cell membrane
enter or leave cell through lipid bilayer or by transport proteins
how can large molecules pass through cell membrane
endocytosis and bulk transport via vesicles
what can monosaccharides pass through cell membrane
diffusion down the concentration gradient
how do carbon dioxide and oxygen cross cell membrane
diffusion, moving from area of high concentration to low concentration
how does K+ move across cell membrane
sodium-pump
how does amino acids and starch cross cell membrane
facilitated diffusion and carrier and channel proteins
active transport
moves substances against their concentration gradient requires energy (ATP) performed by specific proteins embedded in membranes
allows cells to maintain concentration gradients that differ from their surroundings
sodium-potassium pump
type of active transport system
major electrogenic pump of animal cells
PROCESS
1) cytoplasmic Na+ binds to sodium potassium pump
2) Na+ binding stimulates phosphorylation by ATP
3) phosphorylation causes protein to change its shape expelling Na+ to the outside
4) K+ binds on extracellular side and triggers release of phosphate group
5) loss of phosphate group restores protein’s original shape
6) K+ is released and cycle starts over
passive transport
diffusion of a substance across a biological membrane with no energy required from the cell to make it happen
diffusion
net movement of molecules from a higher area of concentration to an area of lower concentration (even spreading of molecules)
facilitated diffusion
transport proteins speed the passive movement of molecules across plasma membrane
osmosis
diffusion of water across selectively permeable membrane
pinocytosis
active transport, type of endocytosis, molecules are taken up when extracellular fluid is “gulped” into tiny vesicles (cellular drinking)
phagocytosis
active transport, type of endocytosis, cell engulfs a particle in a vacuole (cellular eating), vacuole fuses with lysosome to digest particle
3 types of endocytosis
pinocytosis, phagocytosis, receptor-mediated endocytosis
endocytosis
active transport
cell takes in macromolecules by forming vesicles from plasma membrane, reversal of exocytosis
exocytosis
active transport
transport vesicles migrate to the membrane, fuse with it, and release their contents, used by secretory cells to export their products
isotonic
solute concentration is the same as that inside the cell; no net water movement across cell membrane
hypotonic solution
solute concentration is less than that inside the cell; cell gains water
hypertonic solution
solute concentration is greater than that inside the cell; cell loses water
osmoregulation
the control of water balance, is a necessary adaptation for life in such environments
amphipathic
molecule that contains both hydrophobic (nonpolar) and hydrophilic (polar) parts
receptor- mediated endocytosis
binding of ligands to receptors triggers vesicle formation
ligand
any molecule that binds specifically to a receptor site of another molecule
how does bulk transport occur
endocytosis and exocytosis
cotransport
occurs when active transport of a solute indirectly drives transport of another solute
electrogenic pump
a transport protein that generates voltage across a membrane
proton pump
main electrogenic pump of plants, bacteria, and fungi
electrochemical gradient
two combined forces drive diffusion of ions across membranes
chemical and electrical force
chemical force
the ion’s concentration gradient
electrical force
the effect of the membrane potential on the ion’s movement
membrane potential
voltage difference across a membrane
why is facilitated diffusion passive
the solute moves down the concentration gradient
ion channel
channel protein that open or close in response to a stimulus (gated channel)
plasmolysis
in hypertonic environment plant cells lose water, membrane pulls away from wall, death to plant
what do cell walls help to maintain
water balance
turgid
plant cell in hypotonic solution (ideal) swells until the wall opposes uptake, causes cell to become firm
flaccid
plant cell and surroundings in isotonic solution with no net movement of water into cell, plant becomes limp and may wilt
what problems do hypertonic and hypotonic solutions create
osmotic
tonicity
the ability of a solution to cause a cell to lose or gain water
dynamic equilibrium
as many molecules cross one way as cross in the other direction
