ALL LECTURES

Question 1

Define system?

Answer 1

System: a part of the universe in which we are interested in

Question 2

Open system?

Answer 2

On which can exchange both matter and energy with its environment

Question 3

Isolated system?

Answer 3

one which can only exchange energy

Question 4

Closed system?

Answer 4

one which cannot exchange either matter or energy with its surroundings

Question 5

Define the first law of thermodynamics?

Answer 5

energy cannot be lost only transferred

Question 6

Define the second law of thermodynamics?

Answer 6

if the energy of both the system and its surroundings increases, it results in a spontaneous reaction

Question 7

Equation to describe the second law of thermodynamics.

Answer 7

Delta G (universe)>0=Delta g (surroundings) + Delta g (system)

Question 8

Define entropy?

Answer 8

measure of disorder

Question 9

When does delta g apply?

Answer 9

constant temperature, and pressure

Question 10

Equation for delta g?

Answer 10

Delta g= deltaH-TDeltaS

Question 11

Value of delta g at equilibrium? (2marks mention 2 things)

Answer 11

1. Delta G =0

2. min

Question 12

Maxima values of the derivate of delta g vs minima (in terms of the systems stability)

Answer 12

Maxima= unstable as a small change to the conditions of a system will change the equilibrium drastically, will spontaneously move towards equilibrium. Minima= stable = equilibrium (small change in conditions will not change the position of equilibrium)

Question 13

What Is proportional to free energy of a reaction

Answer 13

m0les

Question 14

Endergonic reaction?

Answer 14

position of equilibrium is towards the reactants. Occurs spontaneously in the reverse direction. DeltaG>0

Question 15

Exergonic reaction?

Answer 15

• One in which occurs spontaneously in the forward direction
• DeltaG<0

Question 16

What does delta G not account for? Why?

Answer 16

Activation energy

that is to do with kinetics

Question 17

Two factors effecting Delta G?

Answer 17

Coupled

concentrations

Question 18

Equation which relates free energy and concentration?

Answer 18

Delta G= RTLog(keq)

keq= mass action ratio

Question 19

Mass action ratio

Answer 19

concentration of products/ “ reactants to the power of their moles

Question 20

Standard delta G equation? And what are the conditions for this to be apply?

Answer 20

Delta G= -RTln(keq)

k=298 p=100kpa 1 molar concentrations ph=7

Question 21

Relationship between delta G and Keq?

a) Delta g<0 …. Keq ……..
b) Delta G=O
c) Delta g>0

Answer 21

a) keq>1
b) keq=1
c) keq<1

Question 22

Standard conditions?

Answer 22

298 kelvin
100 kpa
1 molar concentrations
pH=7

Question 23

How do coupled reactions work? (2marks)

Answer 23

couple a exergonic and endergonic reaction together in which there overall DeltaG Is negative and therefore the reaction is feesable

Question 24

ATP?

Answer 24

standard intermediary of energy within cells

Question 25

Example of a metabolic reaction involving ATP which requires coupling?

Answer 25

formation of glucose-6-phophate
using hexokinase enzyme
ATP> ADP +Pi
Glucose +pi> glucose-6-phosphate

Question 26

Cycle in which uses coupled reactions. An example of a coupled reaction within it?

Answer 26

citric acid cycle 
citrate formation 
Pyruvate> acetyle CoA
and acetyl CoA+ Oxalocactate> citrate 
citrate synthase

Question 27

What properties of ATP make it such a great energy currency?(3 marks)

Answer 27

• High energy phosphate bonds
  which have negative Gibbs free energies, therefore easily hydrolysed
• steric clashes between phosphate bonds
• resonance hybrids of single phosphates are stable (therefore prefer to be alone/ hydrolyse)

Question 28

Kinetic stability of ATP? Therefore what is required to aid phosphate transfer, why is this useful?

Answer 28

Kinetically stable therefore an enzyme required. Enables cells to have control over the hydrolysis of ATP etc

Question 29

What type of enzyme is usually used during these ATP hydrolysis.

Answer 29

Kinase

Question 30

Phosphate transfer potentials?

Answer 30

Gibbs free energy in which the transfer of a phosphate to another biological molecule has.