Membrane structure and transport

Question 1

membrane function

Answer 1

• act as selective barrier
• detect chemical messengers at cell surface
• link adjacent cells together by membrane junctions
• anchor proteins
• separate living cells from non-living surroundings

Question 2

membrane structure

Answer 2

• phospholipids bilayer
• globular proteins inserted in the lipid bilayer

Question 3

phospholipid bilayer structure

Answer 3

• glycerol
• 2 fatty acids
• phosphate group

Question 4

integral protein structure

Answer 4

• spans the lipid bilayer (through the membrane)
• non-polar regions are imbedded in the interior of the bilayer
• polar regions protrude from both sides (can’t pull out without ruining)

Question 5

membrane protein functions

Answer 5

• transporters and channels
• enzymes
• cell surface receptors
• cell surface identity marker
• cell to cell adhesion proteins
• attachments to the cytoskeleton
• communication
• protection

Question 6

peripheral protein structure

Answer 6

anchored to a phospholipid in one layer of the membrane
- non-polar regions are inserted in the lipid bilayer
- free to move throughout one layer of the bilayer

Question 7

peripheral protein function

Answer 7

• identity markers
• cell surface identity
• help enzyme process
• bind to cytoskeleton

Question 8

cholesterol function

Answer 8

• aids in fluidity
• helps maintain temperature
• keeps bilayer “untangled”

Question 9

Passive transport

Answer 9

movement of molecules through the membrane in which
- no energy is required
- molecules move in response to a concentration gradient

Question 10

passive transport consists of

Answer 10

• simple diffusion
• facilitated diffusion
• osmosis

Question 11

simple diffusion

Answer 11

• selective permeability
• may require a channel protein to allow polar molecules to pass through

Question 12

facilitated diffusion

Answer 12

movement of a molecule from high to low concentration with the help of carrier protein
- is specific
- is passive
- saturates when all carriers are occupied
- transport balanced by complete inhibitor

Question 13

hypertonic has

Answer 13

a higher solute concentration on the outside so whatever leaves

Question 14

hypotonic has

Answer 14

a lower solute concentration on the outside so water gets absorbed

Question 15

Active transport

Answer 15

• requires energy- ATP used directly or indirectly
• moves substances from low to high
• requires the use of carrier proteins

Question 16

Primary active transport

Answer 16

sodium-potassium pump

Question 17

sodium-potassium pump

Answer 17

• moves 3 NA out of the cell and 2 K into the cell
• ATP energy is used to change the shape of the carrier protein
• affinity of the carrier protein for either NA or K changes so the ion can be carried across the membrane

Question 18

secondary active coupled transport

Answer 18

• uses the energy released when a molecule moves by diffusion to supply energy to active transport of a different molecule

Question 19

Bulk transport

Answer 19

multiple particles going in or out at once
- due to pressure
- non-specific

Question 20

endocytosis

Answer 20

occurs when the plasma membrane envelops food particles and liquids

Question 21

exocytosis

Answer 21

occurs when material is discharged from the cell

Question 22

importance of primary active

Answer 22

• need to have a high enough concentration of sodium and potassium outside
• muscle contraction
• maintain changes