Chapter 8: 8.1 Introduction to Metabolism

Question 1

What provides most of the energy for metabolic reactions?

Answer 1

Electron transfers

Question 2

Many biological molecules need to be…

Answer 2

Reduced

Question 3

What is the mnemonic for oxidation/reduction?

Answer 3

OIL RIG
* Oxidation Is Loss (of an electron) - more bonds to oxygen (an electronegative atom), where applicable
* Reduction Is Gain (of an electron)

Question 4

What are pairs of compounds in which one compound is readily oxidized/reduced called?

Answer 4

Redox pairs

Question 5

Give examples of redox pairs

Answer 5

NADH and NAD+
NAPDH and NADP+

Question 6

What is the reducing power of NADH important for?

Answer 6

ATP synthesis

Question 7

Describe:

NAD

Answer 7

Nictoinamide Adenine Dinucelotide
* Carries electrons on the nicotinamide group

Question 8

How many electrons can NAD+ accept?

Answer 8

Two electrons in the form of a hydride anion (H atom with 2 electrons)

Question 9

Describe:

NADP

Answer 9

Nicotinamide Adenine Dinucleotide Phosphate

Question 10

What is NADPH important in?

Answer 10

Reducing power of NADPH is important in biosynthesis of bio-molecules (e.g. lipids, cholesterol, etc.)

Question 11

Define:

Metabolism

Answer 11

Describes the combined processes of energy production and utilization within living organisms

Question 12

What are the two phases/processes of metabolism?

Answer 12

1. Catabolism
2. Anabolism

Question 13

Define:

Catabolism

Answer 13

The conversion of high energy nutrients to low energy products

Question 14

Catabolism is a ——— process where ATP is ——-

Answer 14

• Oxidative
• Created

Question 15

Anabolism is a ——— process where ATP is ——–

Answer 15

• Reductive
• Utilized

Question 16

What kind of process is catabolism?

Answer 16

An exergonic (spontaneous) process
* Results in the loss of energy from starting material

Question 17

What kind of process is anabolism?

Answer 17

An endergonic (non-spontaneous) process
* Results in disordered and free floating small molecules being converted into ordered macromolecules

Question 18

Define:

Phototrophs

Answer 18

Utilize light energy

Question 19

Define:

Chemotrophs

Answer 19

Utilize energy from oxidized electron donors

Question 20

Define:

Autotrophs

Answer 20

Use CO2 as their source of carbon

Question 21

Define:

Heterotrophs

Answer 21

External organic sources of carbon

Question 22

Define:

Photoautotrophs

Answer 22

Utilize light energy and CO2 as a carbon source

Question 23

Define:

Chemoautotrophs

Answer 23

Utilize energy from oxidized electron donors and CO2 as a carbon source

Question 24

Define:

Photoheterotrophs

Answer 24

Utilize light energy but can not utilize CO2 as a carbon source

Question 25

Define:

Chemoheterotrophs

Answer 25

Utilize energy from oxidized electron donors and but can not utilize CO2 as a carbon source

Question 26

What are the Metabolic Classifications?

Answer 26

• Phototrophs
• Chemotrophs
• Autotrophs
• Heterotrophs
• Photoautotrophs
• Photoheterotrophs
• Chemoautotrophs
• Chemoheterotrophs

Question 27

——- are responsible for carrying out metabolic pathways

Answer 27

Enzymes

Question 28

Metabolic pathways can be regulated at any point, how can the enzymes be regulated?

Answer 28

1. Competitively
2. Non-competitively
3. Allosterically

Question 29

State the formula for:

Gibbs Free Energy Change

Answer 29

ΔG = ΔG’^o +RTln(P/S)

Question 30

State the formula for:

Standard Free Energy Change

Answer 30

ΔG’^o = -RTln(Keq’)

Question 31

State how the reaction progresses if:

1. Keq = 1, ΔG’^o = 0
2. Keq < 1, ΔG’^o > 0
3. Keq > 1, ΔG’^o < 0

Answer 31

1. The reaction is at equilibrium
2. The reverse reaction is spontaneous
3. The forward reaction is spontaneous

Question 32

Unfavourable reactions can be coupled with favourable reactions if…

Answer 32

The sum of the standard free energy is a negative value

Question 33

Define:

Flux

Answer 33

The conversion metabolites through the enzymes involved in the metabolic pathway

Question 34

Define:

High Energy Intermediates

Answer 34

Molecules that can be broken down to release large amounts of energy

Question 35

What does the difference in free energy upon bond breakage depend on?

Answer 35

Stabilization

Question 36

How do we determine the amount of energy released?

Answer 36

The more stable the product, the greater the energy released

Question 37

List:

How to identify a highly stable product

Answer 37

• Elimination of bond strain
• Stabilization by ionization
• Isomerization
• Resonance stabilization

Question 38

ATP can accept or donate…

Answer 38

Phosphates

Question 39

What pathways is ATP involved in?

Answer 39

Involved in both:
* Catabolism and Anabolism pathways

Question 40

Other than ATP, what are some other high energy intermediates?

Answer 40

• Mixed anhydrides
• Enol phosphates
• Thioesters
• Phosphocreatine

Question 41

Describe:

Phosphocreatine

Answer 41

A way of storing high energy phosphates
* ΔG’^o = -43 kJ/mol allows it to be cleaved to produce ATP in a favourable reaction