Membrane Proteins

Question 1

What describes the structure of the plasma membrane?

Answer 1

fluid mosaic model

Question 2

Membranes are comprised of?

Answer 2

a bilayer of phospholipid molecules and a patchwork of protein molecules

Question 3

Phospholipid charge?

Answer 3

The head region of a phospholipid molecule is charged and, therefore, hydrophilic
The tail region is uncharged and non-polar, and, therefore, hydrophobic

Question 4

What gives membrane its fluid quality?

Answer 4

the phospholipids constantly changing position

Question 5

Membrane proteins can be classed as?

Answer 5

integral or peripheral

Question 6

Integral membrane proteins are held firmly in place within the membrane by?

Answer 6

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

Question 7

Some integral membrane proteins are?

Answer 7

transmembrane membranes

Question 8

Peripheral membranes are held to the surface by?

Answer 8

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

Question 9

Many peripheral membrane proteins interact with the surfaces of?

Answer 9

integral membrane proteins

Question 10

The phospholipid bilayer is a barrier to?

Answer 10

ions and most uncharged polar molecules

Question 11

Some small molecules, such as what can pass through the bilayer by simple diffusion

Answer 11

oxygen and carbon dioxide

Question 12

Facilitated diffusion is?

Answer 12

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

Question 13

To perform specialised functions, different cell types have?

Answer 13

different channel and transporter proteins

Question 14

How can water pass through the membrane?

Answer 14

pass across the plasma membrane by diffusing through the phospholipid bilayer or through water channels which are called aquaporins.

Question 15

the direction of water is dependent on what?

Answer 15

the osmotic gradient

Question 16

What are channels?

Answer 16

multi-subunit proteins

Question 17

Most channel proteins in animal and plant cells are?

Answer 17

highly selecctive?

Question 18

Some channel proteins are gated and?

Answer 18

change conformation to allow or prevent diffusion

Question 19

Ligand-gated channels are controlled by?

Answer 19

the binding of signal molecules

Question 20

voltage-gated channels are controlled by?

Answer 20

changes in ion concentration

Question 21

Role of transporter proteins?

Answer 21

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

Question 22

Active transport uses what?

Answer 22

Active transport uses pump proteins that transfer substances across the membrane
against their concentration gradient
A source of metabolic energy is required for active transport

Question 23

Some active transport proteins hydrolyse what?

Answer 23

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

Question 24

What is the electrochemical gradient?

Answer 24

For a solute carrying a net charge, the concentration gradient and the electrical potential difference combine to form the electrochemical gradient that determines the transport of the solute

Question 24

What is the electrochemical gradient?

Answer 24

For a solute carrying a net charge, the concentration gradient and the electrical potential difference combine to form the electrochemical gradient that determines the transport of the solute

Question 25

Ion pumps use energy from what to do what?

Answer 25

Ion pumps, such as the sodium-potassium pump, use energy from the hydrolysis of ATP to establish and maintain ion gradients

Question 26

What is the function of Na/K atpase

Answer 26

It actively transports 3 sodium ions out of the cell and 2 potassium ions into the cell

Question 27

Sodium potassium pump steps?

Answer 27

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

Question 28

The sodium-potassium pump is found in most animal cells, accounting for?

Answer 28

a high proportion of the basal metabolic rate in many organisms

Question 29

Function of sodium potassium pump In the small intestine?

Answer 29

the sodium gradient created by the sodium-potassium pump drives the active transport of glucose

Question 30

Sodium and glucose transport?

Answer 30

The glucose transporter responsible for this glucose symport transports sodium ions and
glucose at the same time and in the same direction