Basics of metabolism Flashcards
Describe the substrates in metabolism
Reduced organic compounds
How is energy from substrates released in metabolism?
Oxidation
Describe the benefit of biological/in vivo oxidation
Can be controlled
Benefit of partial oxidation
Can have various intermediates and trap energy released
What does biological oxidiation usually produce and release?
Energy trapped often as ATP
Waste products usually H2O and CO2
What is catabolism?
Breakdown of compounds to release energy (oxidation)
What is anabolism?
Biosynthesis of compounds from small precursors
Consumes energy and requires reduction
Why is ATP useful?
Provides a short term way to trap energy, (universal cellular energy currency)
What is ATP complexed to?
Mg2+
How is energy stored in ATP?
In each of the phosphate=phosphate bonds
Why is there rapid ATP turnover in cells?
ATP only present in small amounts in cells so need to quickly regenerate to match cellular demand
What is the signal to drive ATP synthesis?
ADP (stimulates oxidation and substrate level phosphorylation to make more ATP)
True or false, low ATP stimulates new ATP production
False
Why is ATP hydrolysis (or ADP) sometimes necessary?
Drive reactions with positive delta G (coupled to the reaction to make delta G< 0)
What is ATP hydrolysis coupled to?
Energy requiring reactions
How are oxidation and reduction reactions linked?
Intermediate molecules store/donate electrons
e.g. NAD+/NADH, FAD/FADH2, NADP+/NADPH
What is produced as compounds enter TCA cycle?
NADH, FADH2, CO2
What is stored in reduce intermediates, what happens to these intermediates?
Electrons stored e.g. NADH or FADH2
They are reoxidised for ATP generation in ETC
What allows controlled oxidation and reduction to occur in same cell?
Compartmentalisation
Where are most NAD+ AND FAD found, why is this good?
Unreduced in mitochondria, so ideal for oxidative reaction
Why is it important to control rate at which metabolic reactions proceed?
Ensure supply meets demand
Forward and reverse pathways not running simultaneously (futile cycling)
What do points of metabolic control have in common
Irreversible?
Irreversible
Energy sensing (rate controlled by energy level in cells)
Why is hydrolysis of AMP to ribose not used as a source of energy?
Phosphate ribose bond stores less energy
What are short term ways that enzyme activity i.e. cell’s metabolism is controlled, how long do they take?
1) Allosteric control (millisecs)
2) Covalent modifications (secs-mins)
3) Translocation (move form one cell compartment to another)
