Membrane Proteins

Question 1

Regions of hydrophobic R groups allow

Answer 1

strong hydrophobic interactions that hold integral proteins within the phospholipid bilayer

Question 2

Some integral proteins are

Answer 2

transmembrane

Question 3

What are peripheral membrane proteins?

Answer 3

Have hydrophilic R groups on their surface and are bound to the surface of membranes, mainly by ionic and hydrogen bond interactions

Question 4

The phospholipid bilayer is a barrier to

Answer 4

ions and most uncharged polar molecules

Question 5

Some small molecules, such as oxygen and carbon dioxide

Answer 5

pass through the phospholipid bilayer by simple diffusion

Question 6

What is facilitated diffusion?

Answer 6

The passive transport of substances across the membrane through specific transmembrane proteins

Question 7

What do different cell types have in order to perform specialised functions?

Answer 7

different channel and transporter proteins

Question 8

Most channel proteins in animal and plant cells are ________ selective

Answer 8

highly

Question 9

Some channel proteins are gated and change conformation to

Answer 9

allow or prevent diffusion

Question 10

What are ligand-gated channels controlled by?

Answer 10

the binding of signal molecules

Question 11

What are voltage-gated channels controlled by?

Answer 11

changes in ion concentration

Question 12

Transporter proteins bind to the

Answer 12

specific substance to be transported and undergo a conformational change to transfer the solute across the membrane

Question 13

Active transport uses

Answer 13

pump proteins that transfer substances across the membrane against their concentration gradient

Question 14

What is required for active transport?

Answer 14

A source of metabolic energy

Question 15

Some active transport proteins hydrolyse ATP directly, to

Answer 15

provide the energy for the conformational change required to move substances across the membrane

Question 16

What does ATPase do?

Answer 16

hydrolyse ATP

Question 17

What is the electrochemical gradient?

Answer 17

A combination of the concentration gradient and the electrical potential difference

Question 18

What does the electrochemical gradient do?

Answer 18

determines the transport of the solute

Question 19

What do ion pumps (eg the sodium-potassium pump) use energy from the hydrolysis of ATP to do?

Answer 19

To establish and maintain ion gradients

Question 20

The sodium-potassium pump actively transports

Answer 20

sodium ions out of the cell and potassium ions into the cell

Question 21

The pump has high affinity for

Answer 21

sodium ions inside the cell; binding occurs; phosphorylation by ATP; conformation changes; affinity for sodium ions decreases; sodium ions released outside of cells, potassium ions bind outside the cell; dephosphorylation ;conformation changes; potassium ions taken into cell; affinity returns to start

Question 22

In the small intestine, the concentration gradient of sodium ions created by the sodium-potassium pump

Answer 22

drives the active transport of glucose

Question 23

The sodium potassium pump is found in

Answer 23

most animal cells

Question 24

The sodium-potassium pump accounts for a

Answer 24

high proportion of the basal metabolic rate in many organisms

Question 25

The glucose transporter responsible for this glucose symport transports

Answer 25

sodium ions and glucose at the same time and in the same direction

Question 26

When is a membrane potential (an electrical potential difference) created?

Answer 26

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

Question 27

For each ATP hydrolysed

Answer 27

3 sodium ions are transported out of the cell and 2 potassium ions are transported into the cell

Question 28

What does the transport of ions establish?

Answer 28

both concentration gradients and an electrical gradient

Question 29

Sodium ions enter the cell down their

Answer 29

concentration gradient, the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient

Question 30

What happens in intestinal epithelial cells?

Answer 30

The sodium-potassium pump generates a sodium ion gradient across the plasma membrane