Metabolism, Basic Concepts and Design - General

Question 1

What are the functions of metabolism?

Answer 1

CASE

1. Get chemical energy in the form of ATP by breaking down energy rich nutrients from the environment or solar energy
2. Convert molecules we ingest into the building blocks of larger molecules needed in the body
3. Assemble small building block molecules into larger molecules like proteins, nucleic acids, lipids and polysaccharides
4. To synthesize and degrade biomolecules that have specialized functions in cells

Question 2

Metabolism is the sum of _____ and _____.

Answer 2

Anabolism, catabolism.

Question 3

A metabolic pathway can be in what 3 “shapes”?

Answer 3

Circular, linear or branched.

Question 4

What are the 3 purposes for the continual input of free energy?

Answer 4

SAP

1. Performance of mechanical work in muscle contractions and cellular movements
2. Active transport of molecules and ions
3. Synthesis of macromolecules and other biomolecules from more simpler forms

Question 5

If a reaction had a K_eq of 0.21, what direction of reaction would be favoured? What about a K_eq of 3.75?

Answer 5

• 0.21: ∆G°’ will be a positive value, meaning that the reverse reaction will be favoured.
• 3.75: ∆G°’ will be a negative value, meaning that the forward reaction will be favoured.

Question 6

ATP has two separate types of bonds that we care about; two of them are between phosphate groups, and one is between the phosphate group and the base. What are each of them called?

Answer 6

Phosphoanhydride bonds between phosphorus groups, ester bonds between phosphorous and base.

Question 7

What are the 4 causes of the large standard free energy change during ATP hydrolysis?

Answer 7

1. Electrostatic repulsion: ATP has 4 negative charges that repel each other
2. Resonance stability: P_i has greater resonance stabilization than any of the phosphates in ATP
3. Increase in entropy: hydrolysis leads to two molecules instead of one
4. Stabilization by hydration: water binds to ADP and P_i which stabilizes these molecules and makes the reversible reaction less favourable

Question 8

What is pyrophosphate? When created from ATP, what are the products?

Answer 8

Two phosphate groups joined together. When created from ATP, PP_i and AMP are products.

Question 9

ATP has a high phosphoryl-transfer potential. What does this mean? What does this translate to?

Answer 9

ATP can readily transfer its phosphate group to water. This allows ATP to not only donate but also accept from certain other molecules.

Question 10

How much ATP do our bodies use per day?

Answer 10

40 kg.

Question 11

Does a more oxidized carbon or a more reduced carbon produce the most energy?

Answer 11

Reduced.

Question 12

What is the ultimate electron acceptor?

Answer 12

O₂

Question 13

What are the two main activated carriers? How many electrons and protons do each of them accept?

Answer 13

1. NAD⁺: 2 electrons and 1 proton
2. FAD: 2 electrons and 2 protons

Question 14

What is the key difference between NADH and NADPH?

Answer 14

NADH is used primarily for the generation of ATP, while NADPH is used primarily for reductive biosynthesis.

Question 15

What vitamin is most important for the generation of activated carriers?

Answer 15

Vitamin B.

Question 16

What 3 ways are metabolic pathways regulated?

Answer 16

1. Amount of enzyme
2. Catalytic activity of the enzymes
   
   1. Allosteric regulation: binding of activators or inhibitors
   2. Reversible covalent modification: response to hormones and other signals, leading to activity change
3. Availability of substrates