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CELL BIOLOGY 2019 > CHAPTER 14 > Flashcards

CHAPTER 14 Flashcards

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1
Q

plasma membrane function?

A

defines cell boundary, is a selective barrier that determines composition of cytoplasm, mediates interactions b/w cell and environment

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2
Q

what is the fundamental structure of the plasma membrane?

A

phospholipid bilayer

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3
Q

what do proteins in the bilayer do?

A

selective transport of molecules and cell to cell recognition

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4
Q

useful as a model for studies of the membrane structure ?

A

RBCs

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5
Q

why is it easier to study RBCs ?

A

they have no nuclei or internal membranes

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6
Q

animal cell membranes have 5 phospholipids?

A

outer leaflet-phosphatidylicholine, sphingomyelin

inner leaflet- phosphatidylethanolamine, phosphatidylserine,phosphatidylinositol

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7
Q

what other two compounds do animal cell membranes contain ?

A

glycolipids and cholesterol

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8
Q

what is the bilayer made up of ?

A

hydrophobic fatty acid chains(impermeable to water soluble fatty acid chains) and they have one or more double bonds which makes kinks in the chain and keeps them form packing together

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9
Q

what are sphingomyelin and glycolipids called together ?

A

sphingolipids

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10
Q

cholesterol and sphingolipids tend to cluster in small semisolid patches called?

A

lipid rafts

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11
Q

most plasma membranes are about 50% lipid and 50% protein by weight. T/F

A

true

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12
Q

what was proposed by singer and Nicolson in 1972?

A

fluid mosaic model

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13
Q

proteins associated with membranes through protein protein interactions with ionic bonds is?

A

peripheral membrane proteins

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14
Q

they are inserted into the lipid bilayer and can only be dissocated by reagents that disrupt hydrophobic interactions?

A

integral membrane proteins

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15
Q

amphipathic molecules with example?

A

hydrophobic and hydrophilic groups that can solubilize these proteins. eg- detergent

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16
Q

integral proteins that can span the lipid bilayer with portions exposed on both sides?

A

transmembrane proteins

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17
Q

what is the transmembrane protein composed of?

A

glycophorin and band 3

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18
Q

what does band 3 do?

A

transporter of HCO3^- and cl^- ions with 14 transmembrane alpha helices

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19
Q

what was the first transmembrane protein to be analyzed by X ray crystallography ?

A

photosynthetic reaction centre of rhodopseudomonas viridis

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20
Q

____ are added to the C terminus of some proteins in the ER.

A

GPI(glycosylphosphatidylinositol) anchors

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21
Q

carbohydrate coat formed by the oligosaccharides of glycolipids and glycoproteins?

A

glycocalyx

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22
Q

functiona of glycocalyx?

A

protects cell surface from ionic and mechanical stress and forms barrier to invading microrganims

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23
Q

what amendments were made to the fluid mosaic model?

A

1-mobility of many plasma membrane proteins is restricted

2-membranes are composed of distinct domains that have different structural and functional roles

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24
Q

the two domains the plasma membrane is divided into are ?

A

apical and basolateral domains

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25
Q

in the small intestine the basolateral surface is covered by microvilli that increase the surface area for absorption. T/F

A

false (apical surface)

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26
Q

the basolateral surface mediates transfer of absorbed nutrients to the blood. T/F

A

True

27
Q

transient structures in which specific proteins can be concentrated to facilitate interactions and are enriched in GPI anchored proteins and transmembrane proteins are ?

A

lipid rafts

28
Q

___ are small lipid rafts that start as invaginations of the plasma membrane organized by cave-in.

A

caveolae

29
Q

caveolae function?

A

endocytosis, cell signalling, regulation of lipid transport, protection of plasma membrane against mechanical stress

30
Q

facilitated diffusion?

A

direction of movement determined by concentration gradients, no energy required

31
Q

how is facilitated diffusion mediated ?

A

by proteins which allow polar and charged molecules to cross the plasma membrane

32
Q

____ ____ bind molecules on one side of the membrane and then undergo conformational changes that allow the molecule to pass through and be released on the other side.

A

carrier proteins

33
Q

____ ____ form open pores through the membrane allowing free diffusion of any molecule of the app. size and charge.

A

channel proteins

34
Q

what compounds do the carrier proteins allow through the membrane by facilitated diffusion ?

A

sugars, amino acids and nucleosides

35
Q

what allows water molecules to cross the membrane rapidly and are impermeable to charged ions allowing passage of water without affecting electrochemical gradients?

A

aquaporins

36
Q

present in nerve and muscle cells and responsible for transmission of electric signals?

A

ion channels

37
Q

what ions do ion channels allow through them?

A

Na+, K+, Ca2+, Cl-

38
Q

these channels open in response to binding of neurotransmitters ?

A

ligand gated channels

39
Q

these channels open in response to changes in the electric potential across the plasma membrane?

A

voltage gated channels

40
Q

the role of ion channels in transmitting electric impulses was first shown using giant squid axons by?

A

Hodgkin and Huxley in 1952

41
Q

ion pumps use energy from ATP to actively transport ions across the plasma membrane to maintain concentration gradients. T/F

A

true

42
Q

__ is pumped out of the cell while ___ is pumped in.

A

Na+,K+

43
Q

nernest equation?

A

the relationship b/w ion conc. and membrane potential

V=RT/zF ln C o/C i

44
Q

as nerve impulses travel along axons, membranes depolarize ?

A

action potential

45
Q

membrane potential goes from what to what in less than a millisecond ?

A
  • 60mV to +30mV
46
Q

Na+ is smaller and narrower than K+. T/F

A

true

47
Q

active transport?

A

molecules are transported against their conc. gradient and energy is provided by ATP

48
Q

examples of active transport?

A

ion pumps and Na+K+ pump`

49
Q

____ Na+ are transported out of the cell and ___K+ into the cell for every ATP(25%) used.

A

3,2

50
Q

what do ion pumps in bacteria, yeasts and plant cells transport ?

A

H+

51
Q

____ have highly conserved ATP binding domains or ATP binding cassettes

A

ABC transporters

52
Q

how was the first eukaryote ABC transporter discovered?

A

product of the mdr(multi drug resistance) gene

53
Q

what happens in cystic fibrosis?

A

defective Cl- transport in epithelial cells results in abnormally thick sticky mucus which obstructs respiratory passages

54
Q

what protein does the cystic fibrosis gene encode?

A

CFTR cystic fibrosis transmembrane conductance regulator

55
Q

symport?

A

transport of two molecules in the same direction eg-uptake of glucose and Na+

56
Q

uniport?

A

transport of a single molecule eg-facilitated diffusion of glucose

57
Q

antiport?

A

two molecules are transported in app. directions

58
Q

endocytosis?

A

allows cells to take up macromolecules, fluids, and large particles such as bacteria

59
Q

phagocytosis?

A

cell eating

60
Q

phagosomes+lysosome ?

A

phagolysosomes

61
Q

what are the professional phagocytes in mammals?

A

MACROPHAGES and neutrophils

62
Q

macropinocytosis?

A

uptake of extracellular fluids in large vesicles

63
Q

sheet like projections of the plasma membrane that curve into open cups followed by membrane fusion to form a large intracellular vesicle /

A

lamelliopodia

64
Q

clathrin mediated endocytosis?

A

mechanism for selective uptake of specific macromolecules

CELL BIOLOGY 2019 (3 decks)

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