Chapter 15 - Metabolism - Basic Concepts and Design

Question 1

3 Stages of the Generation of Energy From Food

Answer 1

1) Large molecules in food are broken down into smaller molecules in the process of digestion.
2) The many small molecules are processed into key molecules of metabolism, most notably acetyl CoA.
3) ATP is produced from the complete oxidation of acetyl CoA.

Question 2

Energy is Needed For

Answer 2

1) Movement (muscle contraction, cells)
2) Active Transport (molecules and ions)
3) Biosynthesis (building complex molecules)

Question 3

Phototrophs

Answer 3

Capture and transforms sunlight energy.

Question 4

Chemotrophs

Answer 4

Get energy from oxidizing carbon fuel.

Question 5

Metabolic Pathways

Answer 5

Stepwise reactions breaking down or synthesizing molecules. Reaction types actually limited. Often common intermediates. Typically defined by a specific substrate getting converted to a specific end point.

Question 6

Intermediary Metabolism

Answer 6

Pathways interacting with other pathways. All reactions within a cell are considered to be this.

Question 7

Systems Biology

Answer 7

An emerging field that attempts to study the pathways all at once.

Question 8

Catabolic

Answer 8

Convert energy from fuel to ATP (breaks down molecules).

Question 9

Anabolic

Answer 9

Requires energy for synthesis (builds molecules).

Question 10

Amphibolic Pathways

Answer 10

Pathways that can be catabolic or anabolic depending on the situation.

Question 11

Anhydride

Answer 11

Formed by removing a water molecule.

Question 12

4 Factors Resulting in Phospho-Anhydrides Having More Energy Than Phospho-Esters

Answer 12

1) Electrostatic Repulsion
2) Resonance Stabilization
3) Increase in Entropy
4) Stabilization Due to Hydration

Question 13

Electrostatic Repulsion

Answer 13

Phosphates have negative charges. Triphosphate of ATP carries 4 negative charges. Negative charges repel each other. Anhydride (ADP and ATP) have more repulsion and ester (AMP) bond has less repulsion.

Question 14

Resonance Stabilization

Answer 14

When phosphates have anhydride bond, the electron sharing is reduced compared with individual phosphates (AMP has more resonance structures than ADP and ATP).

Question 15

Increase in Entropy

Answer 15

Hydrolysis of ATP generates 2 molecules instead of one molecule which increases entropy. The water molecule lost has minimal effect since the system already has a high concentration of water.

Question 16

Stabilization Due to Hydration

Answer 16

More hydrogen bonds possible with ADP and Pi versus ATP (more stabilization and inhibits reverse reaction to form ATP).

Question 17

High Phosphoryl-Transfer Potential

Answer 17

The ability to transfer phosphate groups.

Question 18

Exercise and Energy

Answer 18

Amount of muscle ATP is used rapidly. Creatine phosphate has high phosphoryl-transfer potential (it buffers/regenerates ATP).

Question 19

ATP

Answer 19

An activated carrier of phosphoryl groups.

Question 20

2 Common Characteristics of Activated Carriers

Answer 20

1) The carriers are kinetically stable in the absence of specific catalysts.
2) The metabolism of activated groups is accomplished with a small number of carriers.

Question 21

NADH and FADH2

Answer 21

Activated electron carriers for fuel oxidation.

Question 22

NADPH

Answer 22

Activated electron carriers for synthesis.

Question 23

Coenzyme A

Answer 23

Activated 2-carbon carrier. Contains a sulfur group that is unstable so it can lose it easily.

Question 24

How Metabolic Processes Are Regulated

Answer 24

1) Amount of Enzyme
—> Change gene expression to make more/less enzyme.
—> Enzyme degradation (proteases).
2) Regulate Enzyme Activity
—> Allosteric regulation.
—> Covalent modification ie. phosphorylation.
——> Tied to ATP (energy status).
——> Second messenger regulation.
3) Substrate Accessibility
—> Compartmentalization of reactions in different locations.
——> Flux between compartments controlled.