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bio 130 > 7 intracellular transport > Flashcards

7 intracellular transport Flashcards

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Biology 101 flashcards
1
Q

plasma membrane

A

fatty film studded with protein

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2
Q

main functions of plasma membrane (7)

A
  • separate and protect chemical components of a cell from outside environment
  • selective permeable barrier
  • transport solutes across membrane
  • respond to external signals, signal transduction
  • energy transduction conversion from one form to another
  • compartmentalization for different activities
  • scaffold (structural support) for biochem activities
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3
Q

what environment is cell membrane observed in

A

aqueous environment

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4
Q

lipid bilayer

A

two layers of phospholipids that face tail to tail that have amphipathic properties

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5
Q

amphipathic

A

when a molecule has both hydrophilic and hydrophobic properties

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6
Q

hydrophobic effect

A

all hydrophobic molecules cluster with hydrophilic molecules surrounding

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7
Q

liposomes

A

spherical vesicles formed by pure phospholipids when added to aqueous environment

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8
Q

energetically favourable vs unfavourable

A

phospholipids spontaneously enclose into a sphere with out edges to avoid exposure of hydrocarbon tails to water, which is energetically unfavourable

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9
Q

movement of phospholipids

A

lateral diffusion, exchanging spots, flexing tails, rotation, and flip flop is opposite phospholipid flipping but rare

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10
Q

what is fluidity of a membrane?

A

ease with which lipid molecules move within a plane

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11
Q

what is fluidity dependent on?

A

composition and nature of hydrocarbons in phospholipid, and temperature

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12
Q

what defines nature of hydrocarbons in phospholipid

A

the length and number of double bonds in the hydrocarbon

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13
Q

what makes membrane less fluid?

A

the closer, and regular the packing of tails the less fluid

- the lower the temperature

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14
Q

How does length of hydrocarbon impact fluidity?

A

shorter chains means less interaction and packing, which increases fluidity

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15
Q

saturated hydrocarbon

A

means having maximum number of hydrogens in hydrocarbon chain, so no double bonds

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16
Q

unsaturated hydrocarbon

A

means not having maximum number of hydrogens in hydrocarbon chain, so double bonds

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17
Q

how does double bonds impact fluidity?

A

double bonds form kinks which makes it difficult for hydrocarbons to pack increasing fluidity

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18
Q

what is margarine

A

hydrogenated vegetable oil. The double bonds are removed with the addition of hydrogen to make the liquid oil into solid butter form.

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19
Q

what impact does cholesterol have on membrane?

A

controls fluidity in animal cells. Increase in concentration, decreases fluidity

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20
Q

how does cholesterol impact membrane?

A

cholesterol is short and rigid, and fill the spaces between molecules left by kinks in hydrocarbon tails, stiffening the bilayer

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21
Q

why is membrane fluidity important?

A
  • enables membrane proteins diffuse rapidly
  • cell signalling between proteins
  • ensures membrane molecules distribute evenly when daughter cells divide
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22
Q

how are phospholipids made

A

on cytosolic surface of ER using fatty acids that bind to enzymes

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23
Q

how is the lipid bilayer formed?

A

since flip flopping isnt energetically favourable, enzyme scramblases removes randomly selected phospholipids from one layer and insert them into the other allowing even distribution of new phospholipids

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24
Q

lumen

A

interior space of an organelle

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25
Q

how is asymmetry achieved?

A

enzyme flippases in the golgi apparatus

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26
Q

Is asymmetry preserved?

A

yes. Even when membranes bud off or fuse, the orientation of phospholipids and proteins is conserved

27
Q

why is orientation important?

A

orientation determines funciton

28
Q

glycolipids

A

sugar groups attached to phospholipid head

29
Q

glycolipid orientation and function

A

face exterior, noncytosolic half, as no flippases to transfer glycolipid to cytosolic side, to form coat of carbohydrate that surrounds and protects animal cells

30
Q

inositol phospholipid

A

relay information from cell surface to cell interior

31
Q

how is membrane fluidity regulated

A
  • homeo viscous adaptation where alter membrane lipid composition; shorter chain length, increase double bonds, when low temperature
32
Q

functions of membrane protein (5)

A
  • transport nutrients, metabolites, ions
  • anchor membrane to macromolecules
  • receptors detect chemical signals in environment and relay to interior
  • enzymes that catalyze specific reactions
33
Q

types of proteins and bonding in membrane (5)

A
  • transmembrane extend across bilayer as alpha helix or beta sheets
  • amphipathic or monolayer associated alpha helix where attached to one layer only
  • lipid linked by covalent bond
  • integral membrane proteins found inside of the bilayer
  • weak noncovalent interactions
34
Q

transmembrane receptor protein

A

must be both in the cytosol to pass of message and external to membrane to receive message

35
Q

composition of transmembrane receptor protein

A

the segments in the interior lipid bilayer are composed of hydrophobic amino acids
the segments outside the bilayer has polar amino acids

36
Q

transmembrane hydrophilic pore

A

multiple amphipathic alpha helices

37
Q

porin proteins

A

beta sheet protein with internal hydrophilic and external hydrophobic amino acids in the cylinder found in mitochondria and bacterial membrane

38
Q

membrane domain

A

functionally specialized areas for proteins

39
Q

different types of membrane domains

A
  • attached to cell cortex (internally)
  • extracellular matrix (externally)
  • diffusion barriers restrict proteins to a particular domain
40
Q

significance of epithelial cells

A
  • cells that line the gut
  • apical surface that faces gut contents need specific proteins for nutrients
  • lateral and basal surfaces need specific protein for export of solutes into bloodstream and tissues
41
Q

glycoproteins

A

oligosaccharides linked to proteins located outside plasma membrane

42
Q

proteoglycans

A

one or more long polysaccharide chains located outside plasma membrane

43
Q

glycocalyx

A

carbohydrate layer, sugar coating outside plasma membrane from

44
Q

purpose of glycocalyx

A
  • protects cell surface from mechanical damage
  • absorb water, giving slimy surface helpful for
  • -> movement of motile cell through narrow space
  • -> preventing cells from sticking to one another
45
Q

transporters

A

shift small organic molecules or inorganic ions from one side to the other by changing shape

  • discriminate on basis of molecules and ions that fit into specific binding sites
  • very specific, like enzyme
46
Q

channels

A

hydrophilic pores across membrane through which substances pass by diffusion
- discriminate transporting on basis of size and electric charge

47
Q

what can diffusion through membrane?

A

rapid diffusion only possible for small and more hydrophobic or nonpolar molecules

48
Q

membrane potential

A

voltage difference caused by electrical imbalance across membrane due to imbalance in organic and inorganic ions (Na + outside and Ka+ inside)

49
Q

resting membrane potential

A

when the cell is unstimulated and the anion and cation exchange is balanced across the membrane

50
Q

significance of liposomes

A

impermeable to most water soluble molecules

- protein free artificial lipid bilayer

51
Q

passive transport

A

spontaneous flow of molecules from high to low concentration

  • passive because no additional driving force necessary
  • even though solutes can move in both direction, more will move in than out depending on concentration
  • all channels, most transporters
52
Q

active transport

A

movement of solute against concentration gradient

- carried out by pumps

53
Q

where is energy derived from for

A

membrane potential exerts a formce on molecules that carry electric charge

  • cytosolic side is usually megative potential relative to extracellular side ,
  • -> positive solute into cell, negative solutes driven out of cell
54
Q

electrochemical gradient

A

two forces, concentration gradient, and membrane potential make

55
Q

maintaining osmotic balance

A

osmoconformers - marine organisms adjust internal salt concentration to match seawater
osmoregulators

56
Q

osmosis

A

diffusion of water from high water concentration to low water concentration or low solute concentration to high solute concentration

57
Q

aquaporins

A

protein channel pores that facilitate water movement

58
Q

osmolarity

A

total concentration of solute particles inside a cell

59
Q

turgor

A

pressure from the osmotic swelling in plant cells

60
Q

what transporters does plasma membrane have

A

nucleotide
sugar
amino acid
Na+ pump

61
Q

what transporters does lysosome have

A

H+

62
Q

What transporters does inner mitochondrial membrane have

A

pyruvate

ATP pump

63
Q

what are the types of active transport

A
  • atp driven pumps that hydrolyze atp for uphill transport
  • coupled pumps that link a downhill with an uphill
  • light driven pumps that use energy from the sun to drive up hill transport

bio 130 (5 decks)

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