Chapter 7: Membrane Structure and Function Flashcards Preview

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Flashcards in Chapter 7: Membrane Structure and Function Deck (60):
1

plasma membrane

boundary that separates living cell from its surroundings

2

most abundant lipid in membrane

phospholipids

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amphipathic

contains hydrophilic (head) and hydrophobic (tail) regions

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fluid mosaic

membrane is fluid structure with mosaic of protein

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who discovered the fluid mosaic model

singer and nicolson

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what type of studies supported fluid mosaic model

freeze-fracture

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as temp cools what happens to membrane

becomes less fluid, more solid; membrane can solidify

8

which types of membranes are more fluid

rich in unsaturated fatty acids

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function of cholesterol in membrane

prevent membrane from becoming too solid when cold, too lquid when warm

10

why do variations of lipid composition of membrane occur

adaptations to environment

11

peripheral proteins

bound to surface of membrane, sticks out on one side

12

integral proteins

penetrate hydrophobic core (transmembrane)

13

glycolipid

has carbohydrate chain instead of hydrophilic head

14

glycoproteins

carbohydrate chain bonded to protein

15

6 functions of membrnae proteins

transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix

16

external carbohydrates may vary among

species, individuals, and cell types

17

HIV requires what to enter cell

CD4 and CCR5 receptors

18

why are some individuals resistant to HIV

do not have CCR5 receptors

19

assymetrical distribution of proteins, lipids,and carbs in membrane determined when

membrane is built by ER and golgi bodies

20

hydrophobic molecules can

dissolve in lipid bilayer and pas through membrane

21

what type of molecules do not cross through membrane easily

polar molecules

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transport proteins

allow passafe of hydrophilic substances across membran; specific to a substance

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two types of transport proteins

channel, carrier

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channel protein

have hydrophilic channel that certain molecules/ions can use s tunnel

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aquaporins

channel protein for water

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carrier protein

bind to molecules, change shape, brins molecules into cell

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diffusion

tendency for moecules to spread out evenly into available space

28

diffusion in relation to concentration gradient

diffuses down gradient

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osmosis

diffusion of water across selectively permeable membrane

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tonicity

ability of surrounding solution to cause cell to gain or lose water

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osmoregulation

control of solute concentration and water balance

32

paramecium are hypertonic to environment; how do they maintain homeostasis

contractile vacuole

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cell wall prevents

lysing

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turgid

when no more water can diffuse into the cell (in a hypotonic solution)

35

flaccid

limp (in an isotonic solution)

36

plant cell in a hypertonic solution

cells undergo plasmolysis - plant wilts

37

facilitated diffusion

transport proteins speed passive movement of molecules across membrane

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facilitated diffusion makes use of

channel proteins

39

ion channels

gated channels for specific ions

40

active transport

moves sustances against gradient, allows cell to maintain gradient different from enviroment

41

active transport requires

energy

42

examples of active transport

sodium-potassium pumps

43

membrane potential

voltage difference across a membrane created by difference in distribution of anions and cations across a membrane

44

electrochemical gradient drives

diffusion of ions across a membrane

45

electrogenic pump

transport protein that generate voltage across a membrane

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electrogenic pump in animals

sodium-potassium

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electrogenic pump in plants,fungi, bacteria

proton pump

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electrogenic pumps help store

energy that can be used for work

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cotransport

when active transport of a solute indirectly drives transport of other solutes

50

example of cotransport

plants use H+ gradient generated by proton pump to drive active transport of nutrients into cell

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small molecules/water tracel through membrane via

protein

52

large molecules cross membrane in bulk via

vesicle

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bulk trnaspsort requires

energy

54

exocytosis

transport vesicles outside cells - secretory cells

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endocytosis

cells takes in mecromolecules by forming vesicles from membrane

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types of endocytosis

phagocytosis, pinocytosis, receptor-mediated

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phagocytosis

cell eating - large molecules

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pinocytosis

cell drinking - smalll molecules

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receptor-mediated

recognizes/bonds to substance that is needed; binding of ligand triggers vesicle formation

60

ligand

molecule that bonds to receptor