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Transport across membranes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what are the 4 main functions of the cell surface membrane?

A
  • separates cell contents from outside environment
  • allows different conditions in/out of cell
  • regulates transport of materials
  • cell signaling/recognition
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2
Q

forms a phospholipid….

A

bilayer

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3
Q

3 roles phospholipids in bilayer?

A
  • allow lipid soluble molecules in/out
  • prevent H2O soluble molecules in/out
  • membrane flexible/self sealing
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4
Q

intrinsic protein….(examples)

A

span the whole bilayer i.e. carrier/channel

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5
Q

extrinsic protein…. (examples)

A

partially span the bilayer i.e. extracellular receptors

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6
Q

4 roles of proteins in bilayer

A
  • act as channel/carrier proteins
  • cell surface receptors (hormones/identifying cells)
  • structural support
  • help cells adhere to one another
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7
Q

3 roles of glycoproteins in bilayer

A
  • recognition sites
  • allow cells to recognise each other
  • help cells attach (form tissues)
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8
Q

3 roles of glycolipids in bilayer

A
  • stability of membrane
  • recognition sites (carbohydrate part)
  • cells adhere
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9
Q

3 roles of cholesterol in bilayer

A
  • prevent leakage of H2O/ions
  • cell stable/less fluid at normal temps
  • reduces lateral movement of molecules of membrane
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10
Q

how does cholesterol control membrane fluidity

A

pulls together fatty acid tails (limits movement)

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11
Q

if you increase cholesterol….

A

decrease in fluidity and permeability

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12
Q

why is it called fluid mosaic model

A 
fluid = phospholipid molecules move relative to each other (flexible) 
mosaic = embedded proteins different size/shape/pattern like in a mosaic
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13
Q

full definition of simple diffusion

A

net movement of molecules from a region of high concentration to an area of lower concentration across a selectively permeable membrane until an equilibrium is achieved.

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14
Q

simple and facilitated diffusion is a passive process T or F

A

T

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15
Q

what molecules are able to pass thru the phospholipid bilayer via simple diffusion? + 2 examples

A

small, non-polar molecules and lipid soluble (O2/CO2)

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16
Q

name the 3 ways to increase rate of diffusion

A
  • increase SA
  • increase concentration gradient
  • decreasing length of diffusion pathway
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17
Q

how to increase rate of facilitated diffusion?

A

increase no. of carrier/channel proteins

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18
Q

hydrolysis of ATP is needed for facilitated diffusion. T or F

A

F

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19
Q

definition of osmosis

A

net movement of water molecules from an area of high water potential (less negative) to an area of lower water potential (more negative) thru a selectively permeable membrane.

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20
Q

definition of solute

A

dissolves in a solution

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21
Q

definition of solvent

A

substance that is capable of dissolving 1 or more solutes

22
Q

definition of solution

A

homogenous mixture of 2 or more solutes dissolved in a solution

23
Q

what is the water potential of pure/distilled water

A

0

24
Q

the more solute added to H2O…

A

the lower (more negative) the H2O potential

25
Q

the more negative the water potential…..

A

the less pure

26
Q

if the water potential is higher outside cell (less negative), the solution is________ and water enters making cell become______ and could even cause ______.

A

hypotonic
turgid
lysis

27
Q

if the water potential is equal both in/out of cell, the solution is ______ and there is _____ net movement of water. This is called _________ _______.

A

isotonic
zero
incipient plasmolysis

28
Q

if the water potential is lower (more negative) outside the cell, the solution is _______ and the water ______. This causes the cell to become _______.

A

hypertonic
leaves
plasmolysed

29
Q

definition of active transport

A

movement of molecules/ions from an area of low concentration to an area of high concentration using carrier proteins + the energy released from the hydrolysis of ATP

30
Q

name the 2 similarities between active transport and facilitated diffusion

A
  • both use carrier proteins

- both uses cell plasma membrane

31
Q

name the 3 differences between active transport and facilitated diffusion

A
  • active transport need energy from hydrolysis of ATP
  • active transport goes against concentration gradient
  • active transport only uses carrier proteins
32
Q

give an example of active transport

A

sodium-potassium pump

33
Q

how many Na+ ions bind to the carrier protein? (NA-K pump)

A

3

34
Q

once Na+ ions disassociate with the pump, how many K+ ions bind with the carrier protein? (NA-K pump)

A

2

35
Q

in the sodium potassium pump, how does the inorganic phosphate ion get released from the carrier protein?

A

the bond between the carrier protein and the 2 K+ ions is hydrolysed, releasing the phosphate ion

36
Q

definition of bulk transport

A

when extremely large molecules need to enter (endocytosis) or exit (exocytosis) the cell

37
Q

does bulk transport need ATP

A

yes

38
Q

definition of endocytosis

A

engulfing by the cell surface membrane to form a pinocytic vesicle

39
Q

definition of exocytosis

A

fusion of the lysosome/pinocytic vesicle with the cell surface membrane + releasing contents

40
Q

how does muscle contraction help maintain concentration gradient in the small intestine?

A

moves villi away from gut lumen so allows villi to come into contact with high concentration of digested product

41
Q

give 3 adaptations of the villi +why

A
  • microvilli (increase SA)
  • thin walls (decrease diffusion distance)
  • supply of blood vessels (keep diffusion gradient)
42
Q

absorption of glucose/amino acids by cells lining the mammalian ileum:

  1. Active transport of ______ions from epithelial cells into the _____ thru the ______-potassium pump = sets up conc. gradient
  2. ______ and glucose/aminos diffuse _____ conc. gradient via co-_______ (carrier protein)
  3. increases glucose/aminos in epithelial = _________ diffusion into blood via a _____ protein ______ conc. gradient
A
  1. sodium, blood, sodium
  2. sodium, against, co-transporter
  3. facilitated, channel, down
43
Q

All membranes around/within cells have the _______ basic structure and are called….

A

same, plasma membranes

44
Q

name 5 functions of membranes WITHIN cells

A
  1. control entry/exit of materials into organelles
  2. allow metabolic reactions
  3. provide internal transport system
  4. isolate enzymes which could damage cells i.e. lysosomes
  5. provide surfaces for reactions i.e. RER
45
Q

why can’t charged ions and polar molecules diffuse thru the phospholipids?

A

due to the hydrophobic fatty acid tails of the phospholipid

46
Q
  1. channel proteins allow….

2. carrier proteins allow….

A
  1. specific H2O soluble molecules thru

2. large, non-polar molecules thru

47
Q

in osmosis, H2O moves down a…

A

H2O potential gradient

48
Q

Why do carrier proteins only transport specific substances?

A

have specific tertiary structure, so specific binding sites

49
Q

how does active transport work? (in 4 steps)

A
  1. molecule/ion attaches to receptor
  2. inside organelle: ATP attaches
  3. ATP to ADP + Pi
  4. carrier protein changes shape = release of molecule
50
Q

during the absorption of glucose/amino acids in the mammalian ileum summarise the conc. pathways

A

glucose/aminos enters epithelial AGAINST conc. gradient then moves into the blood DOWN its gradient

Biology (25 decks)

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