MCB Lecture 2 Building Blocks Flashcards Preview

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Flashcards in MCB Lecture 2 Building Blocks Deck (24)
0

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

Half of the dry weight of a cell

1

What are some general functions of protein?

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

2

What is GFP and what is its significance?

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

3

What is molarity?

Concentration of solutes in solvents

4

What are the weak non covalent bonds?

Hydrogen bonds
Van Der Waals interactions
Hydrophobic force

5

What is free energy?

Energy available in a cell that is accessible for chemical reactions

6

What is delta G?

Change in Gibbs' free energy

7

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

Release of energy
Negative delta G

8

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

Absorption of energy
Positive delta G

9

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

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

10

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

Big release of heat or big increase in entropy

11

What does positive delta-H represent?

Absorption of energy

12

What does negative delta-H represent?

Release of heat

13

What does negative delta-S represent?

Decrease in entropy

14

What does positive delta-S represent?

Increase in entropy

15

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

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

16

What is delta-G nought primed?

This is the stand free energy change for a reaction

17

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

Delta-G nought primed = - R T lnKd

18

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

They are reciprocals

19

What does [L] = Kd mean?

Half of the substrate is bound to the enzyme

20

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

Stand lab conditions vs. standard biochemical conditions

21

What are the conditions for delta-G nought primed?

pH 7
[h2o] = 55.5 M

22

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

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

23

How does Kd relate to tightness of binding?
What indicates weak, intermediate and strong binding?

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

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