BCMB20002 MODULE 1: BIOCHEMISTRY | QUESTIONS
AND ANSWERS | 2026 WITH COMPLETE SOLUTION.
L1. What is the symbol + meaning for changes in:
a) Gibbs Free Energy
b) enthalpy
c) entropy
Equations for ∆G? Answer - a) ∆G = change in Gibbs FE
b) ∆H = change in heat
c) T∆S = change in disorder
*T = temperature in K
∆G = Gproducts - Greactants
∆G = ∆H − T∆S
L1. Explain how free energy change is related to spontaneity of a reaction.
What conditions do you need for this to occur?
Give 2 different terms for ∆G and ∆H... Answer - -∆G means a spontaneous
reaction, because parts of the reaction are returning to a lower energy state,
hence releasing excess energy.
,you need big -∆H (exothermic) or big +∆S (increase in entropy)
Exergonic = -∆G, free energy released > spontaneous
Endergonic = +∆G, free energy absorbed > non-spontaneous
Exothermic = -∆H, heat released
Endothermic = +∆H, heat absorbed
L1. Explain how ∆G is different from ∆G'° and how they are related.
∆G at equilibrium?
Standard conditions for ∆G'°? Answer - ∆G = actual free energy change
∆G'° = standard free energy change (fixed value)
refer to screenshot 1
at equilibrium:
∆G = 0
∆G = -RT ln Keq, therefore: ∆G′o = −RT ln Keq
standard conditions for ∆G'°:
- pH 7
- [H+] = 10^-7
- Mg2+ = 1mM
,L1. Predict the direction a reaction will proceed based on ∆G.
How do you get a -∆G (spontaneous reaction)? Answer - if -∆G = reaction will
proceed (spontaneous)
if +∆G = reaction will not proceed (non-spontaneous)
-∆G:
- big -∆H (exothermic)
- big + ∆S (increase entropy)
L1. Theoretical way to make 'unfavourable' reactions go
Give 3 examples of how 'unfavorable' reactions are made favorable Answer -
equilibrium of reaction is: [C][D] / [A][B]
so in order to make reactions go, ensure product [ ] is much smaller than
reactant [ ]
ways to do this:
1. lower [ ] of one product
2. increase [ ] of one reactant
(Le Chatelier's principle)
3. coupled reactions:
- make +∆G and -∆G reactions occur in the same area
- -∆G must outweigh +∆G
- add ∆Gs together, ultimately makes a -∆G
, L1. Explain why ATP is considered an "energy rich" molecule Answer - ΔG' ̊ =
−30.5 kJ/mol, spontaneous
energy is released when bonds formed in products are more stable than bonds
in reactants!
ATP is less stable (and hence has more energy) than ADP + Pi (more stable, less
energy)
So when ATP converts to ADP + Pi, its excess energy is released
*the new bonds that are formed are lower energy. Therefore, when formed,
the excess energy that was keeping the more unstable ATP together is released
L1. Why are amino acids optically active? Answer - because they are non-
superimposable, which gives L-aas and D-aas different properties, namely their
ability to rotate light
all naturally occurring amino acids are L-amino acids
L1. Explain the basis of L- or D-amino acid designations
how to determine? Answer - "D-amino acids" are made by starting synthesis
from D-glyceraldehyde
"L-amino acids" are made by starting synthesis from L-glyceraldehyde
L amino acids - read CORN
AND ANSWERS | 2026 WITH COMPLETE SOLUTION.
L1. What is the symbol + meaning for changes in:
a) Gibbs Free Energy
b) enthalpy
c) entropy
Equations for ∆G? Answer - a) ∆G = change in Gibbs FE
b) ∆H = change in heat
c) T∆S = change in disorder
*T = temperature in K
∆G = Gproducts - Greactants
∆G = ∆H − T∆S
L1. Explain how free energy change is related to spontaneity of a reaction.
What conditions do you need for this to occur?
Give 2 different terms for ∆G and ∆H... Answer - -∆G means a spontaneous
reaction, because parts of the reaction are returning to a lower energy state,
hence releasing excess energy.
,you need big -∆H (exothermic) or big +∆S (increase in entropy)
Exergonic = -∆G, free energy released > spontaneous
Endergonic = +∆G, free energy absorbed > non-spontaneous
Exothermic = -∆H, heat released
Endothermic = +∆H, heat absorbed
L1. Explain how ∆G is different from ∆G'° and how they are related.
∆G at equilibrium?
Standard conditions for ∆G'°? Answer - ∆G = actual free energy change
∆G'° = standard free energy change (fixed value)
refer to screenshot 1
at equilibrium:
∆G = 0
∆G = -RT ln Keq, therefore: ∆G′o = −RT ln Keq
standard conditions for ∆G'°:
- pH 7
- [H+] = 10^-7
- Mg2+ = 1mM
,L1. Predict the direction a reaction will proceed based on ∆G.
How do you get a -∆G (spontaneous reaction)? Answer - if -∆G = reaction will
proceed (spontaneous)
if +∆G = reaction will not proceed (non-spontaneous)
-∆G:
- big -∆H (exothermic)
- big + ∆S (increase entropy)
L1. Theoretical way to make 'unfavourable' reactions go
Give 3 examples of how 'unfavorable' reactions are made favorable Answer -
equilibrium of reaction is: [C][D] / [A][B]
so in order to make reactions go, ensure product [ ] is much smaller than
reactant [ ]
ways to do this:
1. lower [ ] of one product
2. increase [ ] of one reactant
(Le Chatelier's principle)
3. coupled reactions:
- make +∆G and -∆G reactions occur in the same area
- -∆G must outweigh +∆G
- add ∆Gs together, ultimately makes a -∆G
, L1. Explain why ATP is considered an "energy rich" molecule Answer - ΔG' ̊ =
−30.5 kJ/mol, spontaneous
energy is released when bonds formed in products are more stable than bonds
in reactants!
ATP is less stable (and hence has more energy) than ADP + Pi (more stable, less
energy)
So when ATP converts to ADP + Pi, its excess energy is released
*the new bonds that are formed are lower energy. Therefore, when formed,
the excess energy that was keeping the more unstable ATP together is released
L1. Why are amino acids optically active? Answer - because they are non-
superimposable, which gives L-aas and D-aas different properties, namely their
ability to rotate light
all naturally occurring amino acids are L-amino acids
L1. Explain the basis of L- or D-amino acid designations
how to determine? Answer - "D-amino acids" are made by starting synthesis
from D-glyceraldehyde
"L-amino acids" are made by starting synthesis from L-glyceraldehyde
L amino acids - read CORN
