Principles Biochemistry

Question 1

primary protein structure?

Answer 1

a sequence of amino acids

Question 2

secondary protein structure and the 4 subtypes

Answer 2

a polypeptide backbone structure
1. alpha helix

2. beta sheets 1 - can involve >1 chain
3. beta sheets 2 - repeated zig zag antiparrallel structure
4. triple helix - 2 left handed helical chains twisted round each other

Question 3

tertiary protein structure and the 2 types

Answer 3

3D structure of polypeptide
1. fibrous (collagen)
globular (haemoglobin)

Question 4

quaternary protein structure

Answer 4

special arrangement of polypeptide chains with multiple (non-protein) subunits

Question 5

which RNA polymerase synthesises all mRNA

Answer 5

Pol II

Question 6

what does Pol II require to enable transcription to occur

Answer 6

TFIID

Question 7

what are the 3 tRNA binding sites that ribosomes have

Answer 7

Exit
Peptidyl
Aminoacyl

Question 8

what is a cofactor

Answer 8

a metal ion forms a coordination centre in the enzyme

most enzymes need a cofactor to function properly

Question 9

what is an apoenzyme

Answer 9

enzyme without co factor

Question 10

what is a holoenzyme

Answer 10

enzyme with a co factor

Question 11

what is Km

Answer 11

the substrate conc when the reaction rate is 1/2 maximal

Question 12

what is Vmax

Answer 12

the max rate achieved by the system

Question 13

what happens to Vmax and Km in non-competitive inhibition

Answer 13

Vmax is varied

Km is unchanged

Question 14

what happens to Vmax and Km in competitive inhibitor

Answer 14

Vmax unchanged

Km varied

Question 15

what does the Warburg effect suggest

Answer 15

instead of fully respiring in presence of adequate oxygen, cancer cells FERMENT

Question 16

advantages of warburg effect

Answer 16

rapid energy production

rapid cell proliferation

Question 17

disadvantages of warburg effect

Answer 17

H+ and lactase as end products

high glucose consumption, very inefficient ATP synthesis

Question 18

where are all but one of the enzymes of the TCA cycle located

Answer 18

the matrix of the mitochondria

Question 19

what is the name of the one enzyme in TCA cycle located outwith the matrix of mitochondria

Answer 19

succinate dehydrogenase enzyme (located in inner mitochondrial membrane)

Question 20

what are the 2 stages of oxidative phosphorylation

Answer 20

1. electron transport

2. ATP synthesis

Question 21

what is the point of oxidative phosphorylation?

Answer 21

energy from the oxidation of NADH and FADH2 to NAD and FAD is used to pump protons from mitochondrial matrix into inter membranous space

the protons then flow back across the membrane, and this flow is used to phosphorylate ADP to ATP

Question 22

what is gained from each TCA cycle

Answer 22

3NADH
1FADH2
2CO2
GTP

Question 23

what are the 3 control points in glycolysis

Answer 23

1. hexokinase - controls substrate entry
2. phosphofructokinase - controls rate of flow
3. pyruvate kinase - controls product exit

Question 24

what is the role of phosphofructokinase

Answer 24

phosphorylates fructose 6-phosphate, which eventually becomes pyruvate

Question 25

what is the role of pyruvate dehydrogenase complex

Answer 25

catalyses the oxidative decarboxylation of pyruvate to acetyl - CoA

a complex of 3 enzymes allosterically regulated by phosphorylation