Mcat Bio Chem Ch. 8

Front 1

cell (plasma) membrane

Back 1

- semipermeable phospholipid bilayer

- selectively mediated by channels, carriers, and membrane

- fat- soluble compounds cross easily

- "fluid mosaic model"

Front 2

glycoprotein coat

Back 2

- created by carbs associated with membrane-bound proteins

Front 3

Main function of cell membrane

Back 3

- to protect the interior of the cell from the external environment

- selectively regulate traffic

- involved in communication and transport

Front 4

lipid rafts

Back 4

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

- travel within the plane of the membrane

Front 5

flippases

Back 5

- assist in the transition or "flip" between layers

Front 6

fatty acids

Back 6

- type of lipid

- carboxylic acid that contains a hydrocarbon chain and terminal carboxyl group

Front 7

triacylglygerols

Back 7

- storage lipids involved in human metabolic processes

- 3 fatty acid chains, esterfied to a glycerol molecule

Front 8

unsaturated fatty acids

Back 8

- contain one or more double bonds

- liquid form at room temp.

- assist in fluidity to the membrane

Front 9

saturated fatty acids

Back 9

- main components of animal fats

- exist as solids at room temp

- decreases membrane fluidity

Front 10

glycerophospholipid

Back 10

- substituting one of the fatty acids chains of a triacylglycerol with a phosphate group

- "phospholipid"

- used for membrane synthesis and can produce a hydrophilic surface layer on lipoproteins

Front 11

Micelles

Back 11

Small monolayer vesicles that phospholipids spontaneously assemble into

Front 12

Liposomes

Back 12

Phospholipids spontaneously assemble into bilayered vesicles

Front 13

sphingolipids

Back 13

- hydrophilic region and 2 fatty acid tails

- Classes: ceramide, sphingomyelins, cerebrosides, gangliosides

Front 14

Cholesterol

Back 14

- regulates membrane fluidity

- necessary in the synthesis of steroids

- occupies space between phospholipids and can hold them together

Front 15

Waxes

Back 15

- type of lipid

- extremely hydrophobic

- long-chain fatty acid and a long chain alcohol

- high melting point

- provide stability and rigidity within the nonpolar tail region only

- for protection or waterproofing

Front 16

transmembrane proteins

Back 16

- pass completely through the lipid bilayer

- integral protein

Front 17

embedded proteins

Back 17

- only associated with the cytoplasmic or extracellular surface of the cell membrane

- integral protein

Front 18

membrane associated (peripheral) proteins

Back 18

- bound through electrostatic interactions with the lipid bilayer

Front 19

Carbohydrates

Back 19

- attached to protein molecules on the extracellular surface

- hydrophilic

- can act as signaling or recognition molecules

Front 20

membrane receptors

Back 20

- can activate or deactive transporters

- tend to be transmembrane proteins

Front 21

cell adhesion molecules (CAM)

Back 21

- proteins that allows cells to recognize each other and contribute to proper cell differentiation and development

- comprised cell-cell junctions

Front 22

gap junctions

Back 22

- "connexons"

- direct cell-cell communication

- permint movement of water and solutes directly between cells

- composed of 6 molecules of connexin

Front 23

tight junctions

Back 23

- prevent solutes from leaking into the space between cells via paracelluar route

- found in epithelial cells and function as a physical link between the cells

- form a water tight seal

Front 24

desmosomes

Back 24

- bind adjacent cells by anchoring to their cytoskeletons

- formed by interactions btwn transmembrane proteins associated with intermediate filaments inside adjacent cells

Front 25

hemidesmosomes

Back 25

- attaches epithelial cells to underlying structures (basement membrane, ECM)

Front 26

passive transport

Back 26

- spontaneous process that doesn't require energy

- uses concentration gradient for energy supply

- -ΔG

- motivator = increase in entropy (ΔS)

Front 27

active transport

Back 27

- nonspontaneous and require energy

- + ΔG

Front 28

simple diffusion

Back 28

- passive transport

- substrates move down their concentration gradient across the membrane

- only freely permeable particles

Front 29

osmosis

Back 29

- passive transport

- water diffusion from region of lower solute concentration to a higher solute concentration

Front 30

hypotonic solution

Back 30

- concen of solutes in the cell is higher than the surrounding solution

- will cause a cell to swell due to osmosis

Front 31

hypertonic solution

Back 31

- solution is more concentrate than the cell

- will cause the cell to shrink due to osmosis

Front 32

isotonic

Back 32

- solutions inside and outside are equimolar

Front 33

osmotic pressure (π)

Back 33

- sufficient pressure to counterbalance the tendency of water to flow across the membrane

- π = iMRT

M = molarity

R = ideal gas constant

T = absolute gas temp

i= vant hoff factor

Front 34

Van't Hoff Factor (i)

Back 34

- number of particles obtained from the molecule when in solution

Front 35

Facilitated Diffusion

Back 35

- simple diffusion for molecules that are impermeable to the membrane

- energy barrier is too high for molecules to cross freely

- required integral membrane proteins to serve as transporters/channels

Front 36

carriers

Back 36

- for facilitated diffusion

- only open to one side of the cell membrane at any given point

- binding of the substrate = conformational change = occluded state

Front 37

channels

Back 37

- viable transporters for facilitated diffusion

- open = exposed to both sides of cell membrane

Front 38

Active transport

Back 38

- results in the net movement of a solute against its concentration gradient

- requires energy

Front 39

Primary active transport

Back 39

- uses ATP or another energy molecule to transport a molecule across a membrane

Front 40

Secondary Active Transport

Back 40

- " coupled transport"

- harness the energy released by one particle going down its electrochemical gradient to drive another particle up the gradient

Front 41

symport

Back 41

- particles flowing in the same direction across a membrane

Front 42

antiport

Back 42

- particles flow in opposite directions across the membrane

Front 43

endocytosis

Back 43

- cell membrane engulfs material to bring into the cell

- material is encased in a vesicle

- initiated by substrate binding to specific recpetors embedded in the plasma receptors

Front 44

pinocytosis

Back 44

- endocytosis of fluids and dissolved particles

Front 45

phagocytosis

Back 45

- ingestion of large solids like bacteria

Front 46

Exocytosis

Back 46

- occurs when secretory vesicles fuse with the membrane

- releases material from inside the cell to the extracellular environment

Front 47

membrane potential (Vm)

Back 47

- difference in electrical potential across cell membranes

- resting potential is between -40 and -80 mV

Front 48

leak channels

Back 48

- how ions can passively diffuse through the cell membrane over time

Front 49

ion transporter/pump

Back 49

- regulates concentration of intracellular and extracellular ions

Front 50

Nerst Eqn

Back 50

E = RT/zF * ln(ion outside/ion inside)

E = 61.5/z * log(ion outside/ ion inside)

Front 51

Sodium- Potassium Pump

Back 51

- regulates concentration of intracellular and extracellular sodium and potassium ions

- to maintain low concentration of sodium ions and high concentration of potassium ions in the cell

- 3 Na out for every 2 K in

- maintains negative resting potential

Front 52

outer mitochondrial membrane

Back 52

- highly permeable due to many large pores

- completely surrounds the inner membrane

Front 53

inner mitochondrial membrane

Back 53

- much more restricted permeability

- contains cristae (numerous infoldings)

- encloses mitochondrial matrix

- contains very high level of cardiolipin

- does not contain cholesterol