1. Introduction

Question 1

Explain living cells sharing common metabolic features (2)

Answer 1

1. It suggests a common ancestor
2. Evolution leads to change over time as a result of chemical reactions

Question 2

What is metabolism?

Answer 2

Sum of all catabolic and anabolic reactions occurring inside of the cell

Question 3

What is catabolism? (2)

Answer 3

1. Reactions that DEGRADE nutrient molecules
2. RELEASE energy stored in chemical bonds

Question 4

What is anabolism?

Answer 4

1. Reactions that ASSEMBLE large molecules from smaller ones
2. REQUIRE energy supplied by catabolic reactions.

Question 5

What are the 5 biochemical reactions that can occur by either forming or breaking?

Answer 5

1. Group transfer: moves functional group from one molecule to another
2. Internal rerrangement: rearranges atoms within a molecule without adding/removing electrons
3. Cleavage: breaks a molecule into 2 smaller parts
4. Condensation: combining molecules with water
5. Oxidation-reduction: transfer of electrons

Question 6

Explain saturated hydrocarbons (3)

Answer 6

1. Contain C-C and C-h covalent bonds
2. Alipathic molecules (carbons are arranged in an open chain)
3. Nonpolar - covalent bond w equal electron sharing

Question 7

What is electronegativity?

Answer 7

1. Measures the ability of an atom to attract electrons to itself when involved in a chemical bond
2. higher EN= bigger sharer of electrons (greedy; takes e-)
3. smaller EN= smaller sharer of e- (generous, gives up e-)

Question 8

What is a nucleophile with an example (3)

Answer 8

1. Chemical species that forms bonds by donating an electron pair
2. Negative charge
3. Ex) Carboxylate

Question 9

What is an electrophile with an example (3)

Answer 9

1. Chemical species that forms bonds by accepting an electron pair
2. Positive charge
3. Ex) Carboxylic acid

Question 10

What is the first law of thermodynamics?

Answer 10

1. The total energy of the universe is constant
2. Energy is neither created or destroyed

Question 11

What is energy?

Answer 11

The capacity of a system to do work or release heat

Question 12

What are the 4 types of energy forms and explain them

Answer 12

1. Kinetic energy: energy due to motion
2. Potential energy: energy due to position
3. Enthalpy: heat energy at a constant pressure
4. Heat: transfer of electrons from high to low temperature and associated with motions of atoms or molecules.

Question 13

Explain energy change

Answer 13

1. Energy is able to change during a physical or chemical change.
2. The total energy in the system is unchanged though
   - EX) PE + KE = constant

Question 14

What is the second law of thermodynamics?

Answer 14

The entropy of the universe increases

Question 15

What is entropy (s)

Answer 15

Measure of the disorder of a system (J/K)

Question 16

Explain predicting spontaneity (3)

Answer 16

1. Change in enthalpy is NOT a good predictor for spontaneity. For example, a gas mixes spontaneously/irreversibly but there can still be no change in enthalpy
2. BUT Entropy can spontaneously increase
3. Combine first and second law of thermodynamics to predict spontaneous change

Question 17

What is gibb’s free energy (G)

Answer 17

1. The energy available to do work at a constant temp + pressure

Question 18

What is the formula for Gibbs free energy? Explain each.

Answer 18

Delta G = delta H - (Temp)(delta entropy)

H: total energy of the system
TS: wasted energy of the system
G: useful energy of the system

Question 19

Explain positive/negative delta H in gibb’s free energy

Answer 19

Positive:heat is absorbed; ENDOTHERMIC (favours positive G)

Negative: heat is released; EXOTHERMIC (favours negative G)

Question 20

Explain positive/negative delta S in gibb’s free energy

Answer 20

Positive: disorder has increased (ex: solid to gas)

Negative: order has increased (ex gas to solid)

Question 21

Explain cells in the body and free energy (5)

Answer 21

1. Cells remove free energy from sunlight/surroundings
2. Decreases order in the surrounding
3. Increases order within themselves
4. Energy within glucose is internal - KE from vibrations, rotations and translations
5. PE from electrons in chemical bonds

Question 22

What is the law of mass action? (3)

Answer 22

1. Free energy changes drive reactants and products to equilibrium
2. Lowest free energy state
3. Equilibrium described by the equilibrium constant (Keq)

Question 23

Explain positive/negative delta G in gibb’s free energy

Answer 23

Positive: free energy is absorbed; ENDERGONIC (non-spontaneous)

Negative: free energy is released; EXERGONIC (spontaneous)

Question 24

What is the equation for the relationship between free-energy change and equilibrium ?

Answer 24

Delta G = -R T ln Keq
(R = 8.31 J/Kmol)
(T= temp in K)

Question 25

what happens if Keq < 1 ?
Keq > 1?
Keq =1?

Answer 25

Keq < 1 : favours reactants
Keq > 1 : favours products
Keq = 1 : at equilibrium

Question 26

what is the equilibrium constant (Keq) formula?

Answer 26

Keq= [C][D]/[A][B]