Unit 1 KA3

Question 1

What does the fluid mosaic model consist of?

Answer 1

plasma membrane consists of proteins and phosholipids

Question 2

How and why does the phospholipid bilayer hold together?

Answer 2

Regions of hydrophobic R groups allow strong hydrophobic interactions that hold integral membrane proteins within the phospholipid bilayer

Question 3

What are the functions of membrane proteins?

proteins that are embedded into cell membrane

Answer 3

• active transport proteins
• channel forming proteins
• enzymes
• receptors
• attachment proteins for the cell’s cytoskeleton

Question 4

Some integral membrane proteins are…

Answer 4

transmembrane proteins

Question 5

What are Peripheral membrane proteins?

Answer 5

They have hydrophillic R groups on their surface
bound to surface of membranes
by ionic and hydrogen bond interations
they can react with surfaces of integral membrane protiens

Question 6

Phospholipid bilayer

what can pass through, what is it a barrier to?

Answer 6

• barrier to ions and most uncharged polar molecules
• small molecules can pass through by simple diffusion

Question 7

Integral proteins

Answer 7

penetrate hydrophobic interior
folded
hydrophobic R groups form strong interactions

Question 8

Facilitated diffusion

Answer 8

passive transport of substances across thr membrsne through specific transmembrane proteins

Question 9

Transport proteins

Answer 9

use method of facillitated diffusion

Question 10

Channel proteins

Answer 10

use facilitated diffusion
mulit-subunit proteins

Question 11

Ligand-gated channels

Answer 11

controlled by binding of signal molecules
chemical stimulus
correct signal molecule opens gate

Question 12

Voltage-gated channels

Answer 12

controlled by changes in ion concentration

Question 14

Transporter proteins

Answer 14

bind to specific substance to be transproted and undergo a conformational change to transfer the solute across the membrane
each side of bilater is exposed as it alternates conformation

Question 15

Protein pumps

Answer 15

uses active transport
against conc. gradient
needs a source of metabolic energy
some proteins hydrolyse ATP for conformational change

Question 16

What combines together to form the electrochemical grandient that determines the transport of the solute?

when the solute is carrying a net charge

Answer 16

The concentration gradient + electrical potential difference

Question 17

Membrane potential

also known as electrical potential difference

Answer 17

This is created when there is a difference in electrical charge on the 2 sides of the membrane

Question 18

What hydrolase ATP?

Answer 18

ATPases

Question 19

What do transporter proteins do when coupled to an energy source (ATP)

Answer 19

Mediate active transport

Question 20

Concentration grandient

definition

Answer 20

Difference in conc. of a solute across the plasma membrane

Question 21

Where do ion pumps get the energy they use?

Also give an example of an ion pump

Answer 21

Sodium-Potassium Pump
They use energy from hydrolysis of ATP to establish and maintain ion gradients

Question 22

In terms of the Na-K pump what does it do?

Answer 22

Transports ions against a steep conc. gradient using energy directly fro ATP hydrolysis
Actively transports Na+ out of cell and K+ in

Question 23

What is the process of Na-K pump

Answer 23

1. High affinity from Na+ inside cell
2. binding occurs
3. phosporylation by ATP
4. conformation change
5. Affinity for Na+ decreases
6. Na+ released out of cell
7. K+ bind out of cell
8. Dephosphorylation
   9.Conformational changes
   10.K+ taken in cell
   11.. Affinity returns to start

Question 24

For each ATP hydrolysed how many Na+ and K+ are involved?

What is the mneumonic

Answer 24

3 Na+ OUT
2 Ka+ IN

Question 25

Where in the body does the Na-K pump drive the active transport of glucose?

Answer 25

small intestine epithelial

Question 26

How do Na+ enter cell in small intestine?

Answer 26

DOwn the concentration gradient

Question 27

At the same time as Na+ what is transported in the small intestine?

Answer 27

Glucose is pumped into the cell via active transport

Question 28

What and how transports Na+ and glucose in the small intestine?

Answer 28

A glucose transporter is responsible for this glucose symport and transports Na+ and glucose at the same time and in the same direction