Ch. 8: Biological Membranes

Question 1

cell (plasma) membrane general function and structure

Answer 1

semipermeable phospholipid bilayer

Question 2

glycoprotein coat

Answer 2

created by carbohydrates associated with membrane-bound proteins

Question 3

lipid rafts

Answer 3

collections of similar lips with or without associated proteins that serve as attachment points for other biomolecules

Question 4

flippases

Answer 4

assist in the energetically unfavorable process of “flipping” a phospholipid from one side to the other

Question 5

fatty acids

Answer 5

carboxylic acids that contain a hydrocarbon chain and terminal carboxyl group

Question 6

triacylglycerols/tryglycerides

Answer 6

storage lipids involved in human metabolic processes

three fatty acid chains esterified to a glycerol molecule

Question 7

unsaturated fatty acids

Answer 7

one or more double bond in hydrocarbon tail, creates kinks, allows for fluidity

liquid at room temp

“healthier”

Question 8

saturated fatty acids

Answer 8

no double bonding = stack tightly = limited fluidity

main components of animal fats, solid at room temp, processed food, “unhealthy”

Question 9

glycerophospholipid

Answer 9

phospholipid. two fatty acid chains, glycerol molecule, phosphate head

Question 10

micelles vs liposomes

Answer 10

micelles (single layer) and liposomes (double layer)

Question 11

sphingolipids

Answer 11

similar in structure to phospholipids but lack glycerol. Modified to form a variety of biologically necessary molecules (ceramics, sphingomyelins, cerebrosides, gangliosides)

Question 12

role of cholesterol

Answer 12

• regulates membrane fluidity by stabilizing adjacent phospholipids (increases fluidity at low temps, decreases at high temps)
• precursor to steroids

Question 13

waxes

Answer 13

long-chain fatty acid, long-chain alcohol = hydrophobic, high melting point

stability and rigidity to non polar region

cell membranes of plants, not animals, for protection/waterproofing

Question 14

transmembrane proteins

Answer 14

pass through entirety of the bilayer

Question 15

embedded proteins

Answer 15

associated with either cytoplasmic or extracellular aspect of the cell membrane

Question 16

integral proteins

Answer 16

transmembrane + embedded proteins

those that interact with interior of the membrane

Question 17

peripheral proteins

Answer 17

bound through electrostatic interactions with the bilayer

“membrane-associated” proteins

Question 18

where do carbohydrates interact with the membrane

Answer 18

attach to protein molecules on extracellular surface

can form a coat around the cell (d/t interaction with water) or act as signaling/recognition molecules

Question 19

membrane receptors

Answer 19

typically transmembrane proteins that activate/deactivate transporters

Question 20

cell adhesion molecules (CAM)

Answer 20

proteins that forming cell-cell junctions and allow cells to recognize and contribute to each other

Question 21

gap junctions

Answer 21

also called connexons

pores that allow for direct movement of water/solute between cells

formed by the alignment and interaction of six monomers of connexin

Question 22

tight junctions

Answer 22

physical link between cells forming a single layer of tissue

prevent solutes from leaking into intercellular space

Question 23

desmosomes

Answer 23

bind adjacent cells by anchoring to their cytoskeletons

links layers of (usually epithelial) tissue

Question 24

passive transport

Answer 24

• spontaneous

- negative delta G (do not require energy)

Question 25

active transport

Answer 25

- non spontaneous | - positive delta G (require energy)

Question 26

simple diffusion

Answer 26

substrates move down their concentration gradients directly across the membrane

Question 27

osmosis

Answer 27

diffusion of WATER down it's con'c gradient moves from regions of lower solute con'c (dilute) to high solute con'c (concentrated)

Question 28

osmotic pressure and osmosis

Answer 28

osmotic pressure drives osmosis allows entropy to increase

Question 29

equation for osmotic pressure (PI)

Answer 29

PI = iMRT osmotic pressure = van't Hoff factor * molarity * ideal gas constant * absolute temperature (in Kelvins)

Question 30

van't Hoff factor

Answer 30

number of particles obtained from the molecule when in solution glucose = 1, NaCl = 2 (b/c Na+ and Cl-)

Question 31

facilitated diffusion

Answer 31

simple diffusion (down con'c gradient) of molecules impermeable to a membrane integral membranes act as transporters or channels

Question 32

carriers

Answer 32

transport impermeable molecules following a conformation change

Question 33

active transport

Answer 33

net movement of solute against its concentration gradient, requiring energy

Question 34

primary active transport energy source

Answer 34

ATP or another energy molecule powers directly

Question 35

secondary active transport energy source

Answer 35

uses energy molecules to transport by coupling energy released from one molecule going DOWN con'c gradient to drive different particle UP con'c gradient

Question 36

symport

Answer 36

when coupled molecule move in same direction across membrane in secondary active transport

Question 37

antiport

Answer 37

when coupled molecules move in opposite direction across membrane

Question 38

endocytosis

Answer 38

cell membrane invaginate and engulfs material to bring it into the cell within a vesicle

Question 39

pinocytosis

Answer 39

endocytosis of fluids and dissolved particles

Question 40

phagocytosis

Answer 40

endocytosis of large solids (like bacteria)

Question 41

exocytosis

Answer 41

secretory vesicles fuse with membrane and release material from the cell

Question 42

membrane potential

Answer 42

difference in electric potential across cell membranes

Question 43

function of the sodium-potassium pump

Answer 43

Na+ / K + ATPase regulates concentration of intracellular and extracellular sodium and potassium ions

Question 44

how does Na+ / K+ ATPase maintain appropriate stable resting potential

Answer 44

inside of the cell = low Na + and high K+ pumps three Na out for every two K pumped in restores concentration gradients for leak channels

Question 45

outer mitochondrial membrane

Answer 45

large pores = highly permeable to ions and proteins

Question 46

inner mitochondrial membrane

Answer 46

contains cristae (interfoldings) which increase surface area for integral proteins and mitochondrial matrix