Lecture 9: Intro to Metabolism

Question 1

_________: a wide variety of fuel molecules degraded to a few simple units (Ie. ATP)

Answer 1

C__atabolism, a wide variety of fuel molecules degraded to a few simple units (Ie. ATP)

Question 2

_________: a wide variety of biomolecules made from a few building blocks (precursors)

Answer 2

A__nabolism, a wide variety of biomolecules made from a few building blocks (precursors)

Question 3

Overall change in free energy (Delta G) for a pathway must be ________\_

Answer 3

Overall change in free energy (Delta G) for a pathway must be Negative

if delta G is positive, must be linked to exergonic reaction

Question 4

_________\_ obtain their energy from the breakdown (oxidation) of organic compounds

Answer 4

Heterotrophs obtain their energy from the breakdown (oxidation) of organic compounds

Question 5

Enzymes can accelerate the rate of reactions only if they are ____________\_

Answer 5

Enzymes can accelerate the rate of reactions only if they are energetically favorable

Question 6

• Keq= equilibrium constant of a reaction
• Keq> 1, equilibrium towards ______\_ Exergonic or endergonic?
• Keq< 1, equilibrium towards ______\_ Exergonic or endergonic?

Answer 6

• Keq= equilibrium constant of a reaction
• Keq> 1, equilibrium towards products Exergonic
• Keq< 1, equilibrium towards reactants Endergonic

Question 7

Oxidation means the ____\_ of electrons and they are ___________

Answer 7

Oxidation means the loss of electrons and they are Exergonic

taking away the electrons involved in C H bonding and replacing them with electrons from O

Question 8

NAD(P)H/NAD(P) low, cell short of ______\_ power_._

_______\_ favored

Answer 8

NAD(P)H/NAD(P) low, cell short of reducing power,

CATABOLISM favored

Question 9

NAD(P)H/NAD(P) high, the cell has abundant energy,

_______\_ FAVOURED

Answer 9

NAD(P)H/NAD(P) high, cell has abundant energy,

ANABOLISM FAVOURED

Question 10

3 key energy-generating pathways occur in the mitochondrion:

• ________\_ of fatty acids
• _______\_ (oxidation of glucose, amino acids)
• Oxidative phosphorylation (electron transport chain)

Answer 10

3 key energy-generating pathways occur in the mitochondrion:

• beta-oxidation of fatty acids
• TCA cycle (oxidation of glucose, amino acids)
• Oxidative phosphorylation (electron transport chain)

Question 11

Rate Limiting Enzymes:

These enzymes catalyze reactions with large Delta G and K eq making it ______\_

Often the target of ____\_and _____\_ regulators

Answer 11

Rate Limiting Enzymes:

These enzymes catalyze reactions with large Delta G and K eq making it Irreversible

Often the target of Allosteric and hormonal regulators

Question 12

_____\_ has a key role in regulating metabolism of all molecules for consumption by rest of the organs

Answer 12

Liver has a key role in regulating metabolism of all molecules for consumption by rest of the organs

Question 13

What role do cofactors such as NAD and FAD play in metabolic reactions?

Answer 13

NAD and FAD are oxidizing factors that get reduced (ie. Gain electrons)

Question 14

Explain the relationship between vitamins and coenzymes

Answer 14

Relationship between vitamins and coenzymes:

• Oxidation-reduction reactions involves the transfer of electrons from reduced organic compounds to redox cofactors
• ​Many cofactors are vitamins

Question 15

Why must free energy changes be negative for reactions in vivo?

Answer 15

In order to be energy genetically favorable

Question 16

Explain why cleavage of one of ATP’s phosphoanhydridebonds releases large amounts of free energy

Answer 16

• Multiple bonds to be broken
• High energy because of the associated electronegative charges exerting a repelling force between the phosphate group
• When the bond breaks, the products (ADP and one inorganic phosphate group) have a lower free energy than the reactants (ATP and a water molecule).

Question 17

How do phosphorylated compounds, thioesters, and reduced cofactors appear to transfer free energy?

Answer 17

Hydrolysis

Question 18

Why do cells control the metabolic reactions that have large free energy changes?

Answer 18

Because these are the rate-limiting steps that control the rate of entire metabolic pathway

Question 19

Energy is released when organic molecules are ________. Where is this energy captured?

Answer 19

Energy is released when organic molecules are oxidized and this energy is captured as ATP or in redox factors such as NAD