membrane proteins

Question 1

what do regions of hydrophobic r groups allow

Answer 1

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

Question 2

what do Peripheral membrane proteins have

Answer 2

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

Question 3

why do Transporter proteins bind to the specific substance?

Answer 3

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

Question 4

what does active transport use

Answer 4

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

Question 5

what is required for active transport

Answer 5

A source of metabolic energy is required for active transport

Question 6

what do some active transport proteins hydrolyze

Answer 6

Some active transport proteins hydrolyze ATP directly to provide the energy for the conformational change required to move substances across the membrane

Question 7

are some integral proteins are transmembrane proteins

Answer 7

Yes. some integral proteins are transmembrane proteins

Question 8

what do many peripheral membrane proteins interact with

Answer 8

Many peripheral membrane proteins interact with the surfaces of integral membrane proteins

Question 9

what do integral membrane proteins interact extensively with

Answer 9

Integral membrane proteins interact
extensively with the hydrophobic region of membrane phospholipids.

Question 10

what is the phospholipid bilayer

Answer 10

The phospholipid bilayer is a barrier to ions and most uncharged polar molecules

Question 11

how do small molecules pass through the bilayer

Answer 11

Some small molecules, such as oxygen and carbon dioxide, pass through the bilayer by simple diffusion

Question 12

what is facilitated diffusion

Answer 12

Facilitated diffusion is the passive transport of substances across the membrane through specific transmembrane proteins

Question 13

what do different cells have that allow them to perform specialised functions

Answer 13

To perform specialised functions, different cell types have different channel and transporter proteins

Question 14

are most channel proteins in animal and plant cells highly selective?

Answer 14

Yes. Most channel proteins in animal and plant cells are highly selective

Question 15

what are channels

Answer 15

Channels are multi-subunit proteins with the subunits arranged to form water-filled pores that extend across the membrane.

Question 16

what do gated channel proteins do

Answer 16

Some channel proteins are gated and
change conformation to allow or prevent diffusion

Question 17

what are ligand-gated channels controlled by and what are voltage-gated channels controlled by

Answer 17

Ligand-gated channels are controlled by the binding of signal molecules, and voltage gated channels are controlled by changes in ion concentration

Question 18

what are pumps that mediate active transport?

Answer 18

Pumps that mediate active transport are transporter proteins coupled to an energy source

Question 19

what do transporters alternate between

Answer 19

Transporters alternate between two conformations so that the binding site for a solute is sequentially exposed on one side of the bilayer, then the other.

Question 20

what determines the transport of a solute carrying a net charge

Answer 20

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 21

when is a membrane potential created

Answer 21

A membrane potential (an electrical potential difference) is created when there is a difference in electrical charge on the two sides of the membrane.

Question 22

Ion pumps, such as the sodium-potassium pump, use energy from what ?

Answer 22

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

Question 23

what does the sodium-potassium pump do

Answer 23

The sodium-potassium pump transports ions against a steep concentration gradient using energy directly from ATP hydrolysis.
It actively transports sodium ions out of the cell and potassium ions into the cell

Question 24

how does the sodium-potassium pump work as a whole

Answer 24

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 25

For each ATP hydrolysed, three sodium ions are transported out of the …

Answer 25

For each ATP hydrolysed, three sodium ions are transported out of the cell and two potassium ions are transported into the cell. This establishes both concentration gradients and an electrical gradient

Question 26

what type of cells is the sodium-potassium pump most found in

Answer 26

The sodium-potassium pump is found in most animal cells, accounting for a high proportion
of the basal metabolic rate in many
organisms

Question 27

what does the sodium-potassium pump do in the small intestine?

Answer 27

In the small intestine, the sodium gradient created by the sodium-potassium pump drives the active transport of glucose

Question 28

what does the sodium-potassium pump do in the intestinal epithelial cells

Answer 28

In intestinal epithelial cells the sodiumpotassium pump generates a sodium ion gradient across the plasma membrane.

Question 29

what is the glucose transporter responsible for

Answer 29

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

Question 30

how do sodium ions enter the cell

Answer 30

Sodium ions enter the cell down their
concentration gradient; the simultaneous transport of glucose pumps glucose into the
cell against its concentration gradient.