MCB Lecture 2 Building Blocks

Question 0

What are some general functions of protein?

Answer 0

Structure
Enzymes
Hormones (signalling molecules)
Membrane receptors
Channels
Molecular machines

Question 1

What proportion of the dry weight of cells does protein make up?

Answer 1

Half of the dry weight of a cell

Question 2

What is GFP and what is its significance?

Answer 2

Green fluorescent protein
Illustrates the variety of properties that proteins have.
This protein fluoresces all by itself : no chromophore bound
E amino acid sequence produces colour, and guides protein folding

Single point mutations give other colours

Question 3

What is molarity?

Answer 3

Concentration of solutes in solvents

Question 4

What are the weak non covalent bonds?

Answer 4

Hydrogen bonds
Van Der Waals interactions
Hydrophobic force

Question 5

What is free energy?

Answer 5

Energy available in a cell that is accessible for chemical reactions

Question 6

What is delta G?

Answer 6

Change in Gibbs’ free energy

Question 7

What is an exogenous reaction, and what is delta-G for exogenous reactions?

Answer 7

Release of energy

Negative delta G

Question 8

What is an endergonic reaction, and what is delta-G for endergonic reactions?

Answer 8

Absorption of energy

Positive delta G

Question 9

How is delta-G related to delta-H and delta-S?

Answer 9

Delta-G = delta-H - T x delta-S

Question 10

In terms of entropy and heat, what are the requirements for an exogonic reaction?

Answer 10

Big release of heat or big increase in entropy

Question 11

What does positive delta-H represent?

Answer 11

Absorption of energy

Question 12

What does negative delta-H represent?

Answer 12

Release of heat

Question 13

What does negative delta-S represent?

Answer 13

Decrease in entropy

Question 14

What does positive delta-S represent?

Answer 14

Increase in entropy

Question 15

Why is delta-G (change in Gibbs’ free energy) a useful thing for biochemistry?

Answer 15

1. Predict spontaneous reactions
2. Position of equilibrium
3. Tightness of binding

Question 16

What is delta-G nought primed?

Answer 16

This is the stand free energy change for a reaction

Question 17

How does delta-G nought primed relate to K (equilibrium constant)?

Answer 17

Delta-G nought primed = - R T lnKd

Question 18

What is the relationship between equilibrium and dissociation constants? (K and Kd)

Answer 18

They are reciprocals

Question 19

What does [L] = Kd mean?

Answer 19

Half of the substrate is bound to the enzyme

Question 20

What is the difference between delta-G and delta-G nought primed?

Answer 20

Stand lab conditions vs. standard biochemical conditions

Question 21

What are the conditions for delta-G nought primed?

Answer 21

pH 7

[h2o] = 55.5 M

Question 22

What are some of the ways that unfavourable reactions can be made to go?

Answer 22

1. Couple with highly favourable reaction
2. Remove product
3. Have high concentration of reactant

Question 23

How does Kd relate to tightness of binding?

What indicates weak, intermediate and strong binding?

Answer 23

Smaller the Kd, the tighter the substrate-enzyme binding
Weak: mM
Intermediate: microM
Tight: nM