Unit 1: Cells and Proteins KA 1.3: Membrane proteins

Question 1

where are integral (transmembrane) membrane proteins found?

Answer 1

they are embedded into the membrane. Some can be transmembrane and span the entire width of the membrane.

Question 2

what are integral membrane proteins interactions with the membrane?

Answer 2

integral membrane proteins are held in place by strong hydrophobic interactions between the our groups of the protein and the hydrophobic region of the membrane

Question 3

where are peripheral membrane proteins located?

Answer 3

peripheral membrane proteins are located on the surface of the membrane.

they can be intracellular or extracellular

Question 4

how to peripheral membrane proteins interact with the membrane

Answer 4

peripheral membrane proteins have hydrophilic our groups on the surface of the protein and often interact with the surface of integral proteins

bound to the membrane surface by hydrogen and ionic bonds

Question 5

describe the process of facilitated diffusion

Answer 5

The passive transport of substances across the membrane through specific transmembrane proteins such as channels or transporters

Question 6

does facilitated diffusion require energy?

Answer 6

Nope, this process moves substances down their concentration gradient

Question 7

how do ligand gated channels open to let molecules pass through?

Answer 7

ligand channels change confirmation in response to the binding of ligand the protein channel

this confirmational change allows the channel to open and molecules to pass through

Question 8

how do voltage gated channels open to let molecules pass through?

Answer 8

voltage gated channels change confirmation in response to changes in ion concentration

as ions are charged molecules voltage changes

This confirmational change allows the child to open and pass through

Question 9

how to transport proteins facilitate diffusion from the extra cellular to the intracellular space

Answer 9

Molecules spines to transporter on the extracellular side

Confirmation of transporter protein changes and the binding site is now on the intracellular side

The molecule is released from the binding site and the confirmation of the protein returns to the original shape

Question 10

describe ATPases

Answer 10

ATPases are pumps coupled with an energy source that hydrolyse (breakdown using water) ATP directly and these catalyse the conversion of ADP into ADP + pi

this reaction releases energy which brings about the confirmational change required to move the substance across the membrane

Question 11

what is an example of an ATPase?

Answer 11

sodium potassium pump

Question 12

how are molecules transported in active transport?

Answer 12

Against the concentration gradient by pumps like ATPases

Question 13

Does passive transport require energy?

Answer 13

no

Question 14

Does active transport require energy?

Answer 14

Yes

Question 15

name the two different types of passive transport

Answer 15

Simple diffusion and facilitated diffusion

Question 16

what molecules are transported by simple diffusion?

Answer 16

O2 and CO2

Question 17

How are molecules transported into simple diffusion?

Answer 17

Down the concentration gradient and through the bilayer

Question 18

what molecules are transported in facilitated diffusion?

Answer 18

Glucose and water

Question 19

how are molecules transported in facilitated diffusion?

Answer 19

Then the concentration gradient with help of transporters or channels

Question 20

what molecules are transported in active transport?

Answer 20

Ions and glucose (in some areas)

Question 21

what is the concentration gradient?

Answer 21

Difference in concentration of a solute across the plasma membrane

Question 22

what is membrane potential also known as electrical potential difference?

Answer 22

membrane potential is created when there’s a difference in electrical charge on the two sides of the membrane

Question 23

what is the process of the sodium potassium pump?

Answer 23

a) the pump has higher affinity for sodium ions inside the cell, therefore binding occurs

b) the pump hydrolysis ATP and phosphate attaches to it. phosphorylation by ATP causes the confirmation of the protein to change

c) the affinity for sodium ions decrease resulting in sodium being released outside the cell

d) the pump now has high affinity for potassium ions outside the cell therefore binding occurs

e) default realisation occurs which causes the conformation of the protein to change

f) potassium ions are taken into the cell and the process starts again

Question 24

why is the glucose symport classed as active transport?

Answer 24

because glucose needs energy to move across it as it’s moving against its concentration gradient

Question 25

define the term symport

Answer 25

Who transports two substances at the same time in the same direction?

Question 26

in what direction are glucose and sodium move to glucose symport in terms of concentration gradient?

Answer 26

Glucose moves against the concentration gradient

sodium ions move with the concentration gradient