Chapter 7- Membrane Structure and Function

Question 1

Selective Permeability

Answer 1

The plasma membrane regulates which molecules may enter and which may not.

Question 2

Fluid mosaic model

Answer 2

The membrane is a FLUID structure with a mosaic of proteins embedded.

Question 3

2-3 types of membrane proteins- define.

Answer 3

1: Peripheral proteins: bound to the surface (only on one end, does not penetrate)
2: Integral proteins: Penetrate the inside of the membrane (hydrophobic core)
3: Transmembrane proteins: A type of integral protein that penetrates through the ENTIRE membrane.

Question 4

Can phospholipids/proteins in the cell move? Are they motile?

Answer 4

Yes- they are motile and can “flip flop”

Question 5

Lipid rafts

Answer 5

Carry the proteins across the membrane

Question 6

Freeze fracture technique

Answer 6

The technique that freezes the membrane, which makes it be able to get split apart, while preserving the proteins within/on the membrane.

Question 7

Which molecules are favorable in selective permeability? Infavorable?

Answer 7

Favorable: Small, hydrophobic
Unfavorable: Large, hydrophilic, charged

Question 8

Which molecules are favorable in selective permeability?

Answer 8

Small, hydrophobic

Question 9

Which molecules are infavorable in selective permeability?

Answer 9

Large, hydrophilic, charged

Question 10

Small, hydrophobic molecules

Answer 10

Membrane PERMEABLE

Question 11

Are ions membrane permeable?

Answer 11

Completely UNpermeable

Question 12

Impermeable membrane molecules require a _______________________ in order to pass through the membrane.

Answer 12

Transport protein

Question 13

Passive transport vs active transport

Answer 13

Passive transport: No energy (atp) needed
Active transport: Energy requiered

Question 14

Passive transport

Answer 14

High concentration to low concentration. No energy. Diffusion.

Question 15

Two types of diffusion

Answer 15

Simple diffusion: No need for membrane protein. Simply goes from high concentration to low concentration.
Facilitated diffusion: No energy required, uses a membrane protein as a “tunnel”

Question 16

Active transport

Answer 16

Solutes move from areas of low to high concentration.
Energy (ATP) REQUIRED.

Question 17

Diffusion

Answer 17

The tendency for molecules to spread out evenly, requieres no energy.
Eventually reaches equilibrium.
Molecules go down their concentration gradient. (High concentration to low concentration)

Question 18

Osmosis

Answer 18

The diffusion of WATER across a membrane.
Water flows from low to high solute concentration.

Question 19

Tonicity

Answer 19

Ability of an outside solution to cause a cell to gain/lose water.

Question 20

Isotonic solution

Answer 20

The outside amount of solute is equivalent to the inside amount of water. No net water movement.

Question 21

Hypertonic solution

Answer 21

The outside solute concentration is greater. Therefore, water moves out of the cell via osmosis.

Question 22

Hypotonic solutions

Answer 22

The amount of solute concentration is lower outside and more inside the cell. Therefore, more water rushes into the cell.

Question 23

Osmoregulation

Answer 23

The control of water balance within living organisms. (e.g. contractile vacuoles)

Question 24

Channel proteins

Answer 24

Have a hydrophilic channel that molecules/ions can use as a tunnel

Question 25

Carrier proteins

Answer 25

Change shape to shuttle molecules (specific to one "item")

Question 26

Aquaporins

Answer 26

A type of channel protein specifically for transporting water.

Question 27

Ion channels

Answer 27

A type of channel protein taht opens or closes in response to a stimulus (sort of like it needs to be "activated" to be opened"

Question 28

Ion pumps

Answer 28

"Pumps" ions throughout the membrane. Makes one side of the membrane more charged than the other. Creates a membrane potential (voltage difference across a membrane) - E.g. protein pump

Question 29

Membrane potential

Answer 29

Voltage difference across a membrane

Question 30

Electrical force

Answer 30

(membrane potential) The force based on the charges of both sides of the cell membrane, that helps determine the direction that IONS are transported.

Question 31

Electrochemical gradient

Answer 31

Determines the directions ions are transported passively. 1: Chemical force (concentration gradient) 2: Electrical force (membrane potential)

Question 32

Cotransport

Answer 32

When active transport of a solute indirectly drives transport of another solute

Question 33

Uniporter

Answer 33

A transport protein that moves one molecule in one direction

Question 34

Symporter

Answer 34

A transport protein that moves two molecules in the same direction

Question 35

Antiporter

Answer 35

A transport protein that moves two molecules in opposite directions

Question 36

How do large molecules (polysaccharides/proteins) transport across the cell membrane?

Answer 36

Through transport vesicles

Question 37

Exocytosis vs Endocytosis

Answer 37

Exocytosis: The molecules are moved OUT of the cell Endocytosis: The molecules are moved INTO the cell

Question 38

Phagocytosis

Answer 38

"Cellular eating" Engulfs large particle in vacuole, then fuses with the lysosome to digest

Question 39

Pinocytosis

Answer 39

"Cellular drinking" "Sips" up droplets of little particles/fluids and uses vesicles to bring it into the cell

Question 40

Receptor-Mediated Endocytosis

Answer 40

Cell membrane has many receptors that bind to very specific substances. Allows the cell to receive very specific substances in BULK.