more things im forgetting ill probably delete this deck later x

Question 1

why is substrate concentration able to stop being a limiting factor in a reaction

Answer 1

the enzymes can become saturated, and will be working at their maximum possible rate

Question 2

name the type of proteins that are translated in ribosomes on the RER and enter its lumen

Answer 2

transmembrane proteins

Question 3

what are the fates of lipids that are synthesised in the ER

Answer 3

they can become part of cytosolic lipid droplets and stored or transported to the ER for secretion. they are fats

Question 4

what changes would result in a decrease in the affinity of haemoglobin for oxygen

Answer 4

increased temperature and decreased pH

Question 5

what is the name of the covalent bond that stabilises the teritiary structure of a protein

Answer 5

disulphide

Question 6

state which form of post translational modification can cause reversible conformational change in proteins

Answer 6

addition or removal of a phosphate

Question 7

give examples of cellular proteins where their activity is affected by the conformational change following phosphorylation

Answer 7

enzymes and receptors

Question 8

state the type of interactions that are disrupted in the unphosphorylated protien

Answer 8

ionic interactions

Question 9

give five ways in which the r groups of an amino acid can vary

Answer 9

• size
• shape
• charge
• hydrogen bonding capacity
• chemical reactivity

Question 10

state how a phospholipid differs to a triglyceride

Answer 10

former has 2 fatty acids, latter has 3

Question 11

name the proteins that interact extensively with the hydrophobic region of the membrane phospholipids

Answer 11

integral membrane proteins

Question 12

state which r groups peripheral membrane proteins contain on their surface

Answer 12

hydrophilic

Question 13

give two interactions that bind peripheral membrane proteins to the surface of the membrane

Answer 13

ionic and hydrogen bonds

Question 14

state which molecules the phospholipid bilayer is a barrier to

Answer 14

ions and most uncharged polar molecules

Question 15

name the different types of transporter proteins and their functions

Answer 15

• aquaporins - passage of water through cells
• GLUT - glucose transport
• sodium channels - sodium in the cell
• potassium channels - only allow potassium ions to pass through them
• calcium channels - specific for calcium ions only

Question 16

state what the sodium potassium pump accounts for a high proportion of in animal cells

Answer 16

the basal metabolic rate

Question 17

describe glucose symport.

Answer 17

• the glucose transporter responsible for glucose symport transports sodium ions and glucose at the same time and in the same direction.
• the sodium ions enter the cell down their concentration gradient; the simultaneous transport of glucose pumps glucose into the cell against its concentration gradient

Question 18

what combines to form the electrochemical gradient

Answer 18

concentration gradient and electrical potential difference

Question 19

describe how transporter proteins transfer the solute across the membrane

Answer 19

the transporter proteins bind to the specific substance to be transported and undergo a conformational change to transfer the solute across the membrane. the transporters alternate between two conformations so that the binding site for a solute is sequentially exposed on one side of the bilayer and then the other.

Question 20

describe what is meant by a pump protein

Answer 20

transporter proteins coupled to an energy source

Question 21

give a feature of channel proteins that make them able to allow or prevent diffusion

Answer 21

they are gated, and can change conformation

Question 22

give a feature of channels

Answer 22

they are highly selective

Question 23

name the type of transmembrane protein that allows for passive transport

Answer 23

channel protein

Question 24

how do signals reach the cytosol

Answer 24

via signal transduction pathways

Question 25

in hydrophilic signalling, describe the process that changes the behaviour of the cell

Answer 25

the conversion of extracellular ligand binding to intracellular signals

Question 26

describe the results of insulin binding to its receptror

Answer 26

conformational change triggers the phosphorylation of the receptor. intracellular signalling cascade that triggers recruitment of glut4 transporter proteins to the cell membrane of fat and muscle cells

Question 27

describe how insulin stimulate the uptake of glucose into cells

Answer 27

the insulin binding to its receptor results in the receptor changing conformation. this triggers an intracellular signalling cascade, which results in glut4 containing vesicles being transported to the cell membrane of muscle and fat cells

Question 28

what is meant by signal transduction

Answer 28

signal molecules cant enter the cell through the membrane. they are instead transduced via receptors, which then initiates the response.

Question 29

how is membrane potential maintained

Answer 29

sodium potassium pump

Question 30

name the molecule that receptors are made from

Answer 30

ligands

Question 31

name the signal that is sent down the axon

Answer 31

action potential

Question 32

what happens to rhodopsin when retinal absorbs a photon of light

Answer 32

changes conformation to photoexcited rhodopsin

Question 33

photoexcited rhodopsin activates a g protein called…

Answer 33

transducin

Question 34

what affects the function of ion channels in the membrane of rod cells

Answer 34

the reduction in the concentration of cyclic GMP as a result of its hydrolysis.

Question 35

describe the series of events that triggers nerve impulses in neurons in the retina

Answer 35

• retinal absorbs photon of light.
• rhodopsin becomes photoexcited
• this activates transducin
• transducin activates PDE
• PDE catalyses the hydrolysis of cyclic GMP
• the reduction in concentration of cyclic GMP results in a closure of ion channels in the membrane of the rod cells
• this triggers nerve impulses in neurons in the retina