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7 intracellular transport 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
how is asymmetry achieved?
enzyme flippases in the golgi apparatus
26
Is asymmetry preserved?
yes. Even when membranes bud off or fuse, the orientation of phospholipids and proteins is conserved
27
why is orientation important?
orientation determines funciton
28
glycolipids
sugar groups attached to phospholipid head
29
glycolipid orientation and function
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
inositol phospholipid
relay information from cell surface to cell interior
31
how is membrane fluidity regulated
- homeo viscous adaptation where alter membrane lipid composition; shorter chain length, increase double bonds, when low temperature
32
functions of membrane protein (5)
- transport nutrients, metabolites, ions - anchor membrane to macromolecules - receptors detect chemical signals in environment and relay to interior - enzymes that catalyze specific reactions
33
types of proteins and bonding in membrane (5)
- 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
transmembrane receptor protein
must be both in the cytosol to pass of message and external to membrane to receive message
35
composition of transmembrane receptor protein
the segments in the interior lipid bilayer are composed of hydrophobic amino acids the segments outside the bilayer has polar amino acids
36
transmembrane hydrophilic pore
multiple amphipathic alpha helices
37
porin proteins
beta sheet protein with internal hydrophilic and external hydrophobic amino acids in the cylinder found in mitochondria and bacterial membrane
38
membrane domain
functionally specialized areas for proteins
39
different types of membrane domains
- attached to cell cortex (internally) - extracellular matrix (externally) - diffusion barriers restrict proteins to a particular domain
40
significance of epithelial cells
- 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
glycoproteins
oligosaccharides linked to proteins located outside plasma membrane
42
proteoglycans
one or more long polysaccharide chains located outside plasma membrane
43
glycocalyx
carbohydrate layer, sugar coating outside plasma membrane from
44
purpose of glycocalyx
- 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
transporters
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
channels
hydrophilic pores across membrane through which substances pass by diffusion - discriminate transporting on basis of size and electric charge
47
what can diffusion through membrane?
rapid diffusion only possible for small and more hydrophobic or nonpolar molecules
48
membrane potential
voltage difference caused by electrical imbalance across membrane due to imbalance in organic and inorganic ions (Na + outside and Ka+ inside)
49
resting membrane potential
when the cell is unstimulated and the anion and cation exchange is balanced across the membrane
50
significance of liposomes
impermeable to most water soluble molecules | - protein free artificial lipid bilayer
51
passive transport
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
active transport
movement of solute against concentration gradient | - carried out by pumps
53
where is energy derived from for
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
electrochemical gradient
two forces, concentration gradient, and membrane potential make
55
maintaining osmotic balance
osmoconformers - marine organisms adjust internal salt concentration to match seawater osmoregulators
56
osmosis
diffusion of water from high water concentration to low water concentration or low solute concentration to high solute concentration
57
aquaporins
protein channel pores that facilitate water movement
58
osmolarity
total concentration of solute particles inside a cell
59
turgor
pressure from the osmotic swelling in plant cells
60
what transporters does plasma membrane have
nucleotide sugar amino acid Na+ pump
61
what transporters does lysosome have
H+
62
What transporters does inner mitochondrial membrane have
pyruvate | ATP pump
63
what are the types of active transport
- 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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