Lecture 15 - Metabolic Concepts

Question 1

What is Metabolism

Answer 1

Network of thousands of enzyme catalysed reactions occuring in the cell
Can be either catabolic or anabolic
Reactants and products of metabolism known as metabolome
Metabolism describes flow of matter and energy within an organism

Question 2

Metabolism and Proteins

Answer 2

Metabolism involves proteins and metabolites
Proteins determine flow of matter and energy trhough the metabolic network
Total complement of proteins in an organism called proteome

Question 3

Partial Proteome Categories

Answer 3

Secretome - proteins secreted by cell
Peptidome - small molecular weight peptides
Phosphoproteome - collection of phosphoproteins
Glycoproteome - collection of glycosylated proteins

Question 4

Metabolome

Answer 4

All metabolites in an organism at a particular time and in particular conditions

Question 5

Metabolic Pathways

Answer 5

Particular series of chemical reactions that seems to achieve a particular end
Many chemical reactions proceed spontaneously at similar rates without interference
Metabolites flow through the pathways over time is called the metabolic flux

Question 6

Anabolic Pathways

Answer 6

Biosynthesis - making molecules
Reductive 
Requires energy
Divergent 
Uses NADPH as electron donor

Question 7

Catabolic Pathways

Answer 7

Degradative - breaks molecules
Oxidative 
Yields energy 
Convergent 
Use NAD+ and FAD as electron carriers

Question 8

Types of Chemical Reactions

Answer 8

Functional group transfer
Oxidations and reductions
Rearrangement reactions - bond structure rearranged around one or more C
C-C bond cleavage and formation reactions
Condensation reactions - two molecules join with elimination of water

Question 9

Control of Metabolism

Answer 9

Needs to be controlled to:
- respond to cellular and physiological needs
- respond to changes in energy demand
- prevent substrate cycles
Controlled by:
- thermodynamics of reactions
- amount of enzymes
- activity of enzymes

Question 10

How does Compartmentalisation and Hormones have control on Metabolism?

Answer 10

Compartmentalisation - keep related reactions apart by putting them in different locations (organelles)
Hormones - acting on cells through membrane bound, cytosolic or nucleic receptors

Question 11

Channeling

Answer 11

Direct transfer of reaciton product from active site of one enzyme to active site of subsequent enzyme catalysing the next step in pathway
Advantages:
- improves catalytic efficiency
Disadvantages:
- intermediates dont pass into bulk solution and may prohibit development of metabolic branch points