1.3 : membrane proteins

Question 1

what is a fluid mosaic model

Answer 1

a model that describes the structure of the cell membrane

Question 2

integral protiens

Answer 2

are protiens that are embedded in the membrane as they have hydrophobic R groups that hold them within the bilayer

Question 3

transmembrane protien

Answer 3

integral protiens that span across the whole membrane

Question 4

peripheral membrane

Answer 4

bound to the surface of the membrane and have hydrophyllic R groups that bind them to surface by ionic and hydrogen bonds

Question 5

phospholipid bilayer

Answer 5

barrier to ions and most uncharged polar molecules, small molecules like oxygen and co2 can pass through with just diffusion

Question 6

facilitated diffusion

Answer 6

passive transport of substances across the membrane through specific transmembrane protiens

Question 7

transporter protiens

Answer 7

bind to a specific solute and to be transported and undergo a conformational change to transfer substance across the membrane
alternate between two conformational changes so that a solute is exposed on one side then the other

Question 8

channel protiens

Answer 8

multi subnit protiens, in which the subunit are arranged to form water filled pores that extend across the membrane. in animal and plant cells most of these protiens are selective. some of them are also gated

Question 9

ligand gated channel

Answer 9

a ligand is a molecule that binds to a protien and the ligand gated channels are controlled by the binding of signal molecules

Question 10

voltage gated channels

Answer 10

controlled by the changes of ion concentration

Question 11

active transport

Answer 11

uses pump protiens that transfer across the membrane against there concentration gradient,
some of these protiens are ATPase which hydrolyse ATP to provide energy for conformational change

Question 12

solute carrying a net charge

Answer 12

the concentration gradient and electrical potential difference combines to form electrochemical gradient that determines the transport of the solute

Question 13

membrane potential

Answer 13

( electrical potential difference) is created when there is a difference in electrical charge on both sides of the membrane

Question 14

ion pumps

Answer 14

uses energy from hydrolysis of ATP to establish and maintain ion gradients

Question 15

sodium potassium pump step 1

Answer 15

there is high affinity for the sodium ions outisde of the cell and the hydrolysis of ATP occurs

Question 16

sodium potassium pump step 2

Answer 16

binding occurs within the cell and the conformation changes and is phosphorylysed by ATP which means the affinity for sodium ions is now low so 3 sodium ions are released out of the cell

Question 17

sodium-potassium pump step 3

Answer 17

there is now a high affinity for potassium ions so binding will occur outside the cell

Question 18

sodium potassium pump step 4

Answer 18

dephosporylation occurs and conformation changes so affinity decreases for k+ ions and 2 are released into the cell and the affinity returns to the start

Question 19

what does the sodium-potassium pump account for in animal cells

Answer 19

basal metabolic rate

Question 20

sodium potassium pump in the small intestine

Answer 20

creates a sodium ion gradient that drives the active transport of glucose across the plasma membrane

Question 21

glucose transport in the intestine

Answer 21

glucose transporter responsible for glucose symport transports sodium ions and glucose at the same time and in the same direction
sodium ions enter the epithileal cell going down the gradient whih transports glucose into cell against gradient

Question 22

function of sodium potassium pumps

Answer 22

generation of ion concentration gradient for glucose symport