M1: Metabolism & Thermodynamics L1

Question 1

Define metabolism

Answer 1

The process through which living systems acquire and utilize the free energy they need to carry out their various functions. How food is transformed to provide energy.

Question 2

What 2 processes make up metabolism?

Answer 2

1. Catabolism

2. Anabolism

Question 3

Define catabolism

Answer 3

Degradation (complex metabolites to simple molecules). Nutrients and cell constituents are broken down to salvage their components and or to generate free energy.

Question 4

Define anabolism

Answer 4

Biosynthesis (simple metabolites to complex metabolites). Biomolecules are synthesized from simpler components.

Question 5

What is an energy balance?

Answer 5

A balance between energy intake and energy expenditure.

Question 6

What constitutes energy intake

Answer 6

Food intake.

Question 7

What constitutes energy expenditure?

Answer 7

Standard metabolic rate (SMR) + activities + exercise

Question 8

Define standard metabolic rate (SMR)

Answer 8

Basic energy consumption at rest (housekeeping).

Question 9

What is a negative energy balance?

What’s an example

Answer 9

When energy expenditure is greater than energy intake.

Ex: anorexia, cachexia, death

Question 10

What is a positive energy balance?

What’s an example?

Answer 10

When energy intake is greater than energy expenditure.

Ex: weight gain, obesity, type 2 diabetes, death

Question 11

What are the 5 principles of metabolic pathways?

Answer 11

1. metabolic pathways are irreversible.
2. metabolic pathways have a first committed step.
3. metabolic pathways are regulated.
4. metabolic pathways catabolic and anabolic pathways must differ.
5. metabolic pathways occur in specific locations in eukaryotic cells.

Question 12

Explain why metabolic pathways are irreversible

Answer 12

A highly exergonic reaction is irreversible therefore, if an exergonic reaction is part of a multistep metabolic pathway, it confers directionality to the pathway. Makes the entire pathway irreversible.

Question 13

How do you regulate a metabolic pathway?

Answer 13

By regulating the rate limiting step you exert control over the flux of metabolites.

Question 14

Are living organisms in an equilibrium or non-equilibrium state?

Answer 14

A non-equilibrium state

Question 15

Explain why living organisms are in a non-equilibrium state

Answer 15

Living organisms are an open system that need constant energy input because we waste energy in the form of heat and we also have the SMR that consumes energy even at rest.

Question 16

What is the Gibb’s Free Energy equation?

Answer 16

If A + B -> C + D then,
∆G = ∆G˚’ + RT ln ([C] [D] / [A] [B])
∆G = ∆G˚’ + RT ln (Keq)

Question 17

What does ∆G˚’ indicate?

Answer 17

It indicates the nature of the reaction (endergonic Vs exergonic). It’s a crude indication of the likelihood of a reaction being physiologically reversible if everything was at unit concentrations (1 mole).

Question 18

What does it mean if ∆G˚’ > 0?

Answer 18

The reaction is endergonic. Requires input of free energy.

Question 19

What does it mean if ∆G˚’ < 0?

Answer 19

The reaction is exergonic. Produces energy.

Question 20

What does ∆G indicate?

Answer 20

True indication of the direction of a reaction (likelihood of its reversibility or irreversibility in vivo). Determines spontaneity.

Question 21

What does it mean if ∆G = 0?

Answer 21

Reaction is at equilibrium and reversible in vivo.

Question 22

What does it mean if ∆G > 0?

Answer 22

Reaction is not spontaneous in vivo. requires free energy.

Question 23

What does it mean if ∆G < 0?

Answer 23

Reaction is spontaneous in vivo. processes that can be utilized to do work.