intro to metabolism

Question 1

what is metabolism?
- what are metabolites
- what is a metabolic pathway
- are reactions reversible or irreversible

Answer 1

• The sum of chemical reactions occurring in a living organism
• the substances used in metabolic reactions
• where products of 1 reaction are reactant in next
• reversible

Question 2

what determines the way a reaction will go?

Answer 2

• free energy changes

Question 3

determinants of free energy change (3)

Answer 3

• change in enthalpy (equal to the overall change in bond energies, associated with the energy required to break the covalent bonds)
• change in temperature (less of an impact in body as its tightly regulated)
• change in entrapy (increases in a system that becomes more disordered, decreases as becomes more structured - many biological reactions result in increased order eg. Solution of Proteins lower entropy than solution of amino acids)

Question 4

Parameters affecting the change in free energy of a reaction
- what is the standard free energy change of a reaction

Answer 4

• temperature, pressure, pH, initial amounts of reactants and products
• delta G nought prime

Question 5

favoured and unfavoured reactions
- when is a reaction favoured and unfavoured

Answer 5

• When Free energy of products is lower than reactants its favoured and energy is released for work (exergonic reaction- diff to exothermic as it does not change surrounding temp)
• When amount of free energy is more in products than reactants its unfavoured and energy has to be put in for reaction to work (endergonic reaction)

Question 6

ATP and energy release-
- structure of ATP
- what happens when ATP is hydrolysed
- standard free energy change of Atp + H20 to ADP + Pi + H+and what it means

Answer 6

• ATP is made of adenine, ribose sugar, and 3 phosphoryl groups joined together by 2 phosphoanhydride linkages (where the energy content of ATP is stored)
• forms ADP (once) and AMP (twice) and releases energy
• -6.3 kcal.mol-1 so favoured thermodynamically and ATP referred to as a high energy compound releasing lots of energy.

Question 7

what is anabolism?

Answer 7

• the synthesis of larger molecules from smaller ones

Question 8

what is catabolism?

Answer 8

• Catabolism of large molecules to small molecules releases energy for synthesis of ATP

Question 9

REDOX reactions
- how is a compound oxidised
- how is a compound reduced

Answer 9

• loses hydrogen and electrons and accepts oxygen
• accepts hydrogen and electrons and loses oxygen

Question 10

NAD
- what is its oxidised and reduced form
when is it common in metabolism

Answer 10

• NAD+ oxidised
• NADH reduced
• exercise metabolism (eg. oxidative phosphorylation)

Question 10

2 other redox compounds

Answer 10

• Nicotinamide adenine dinucleotide phosphate (NADP)
• Flavin adenine dinucleotide (FAD)

Question 11

summary of oxidants and reductants-
- the oxidants and what they do
- the reductants and what they do
- what marks the end of oxidation

Answer 11

• NAD+, NADP+ and FAD accept H
• NADH, NADPH and FADH2 donate H/electrons
• Transfer of electrons from NADH and FADH2 to O2 creating water