Bioenergetics And High Energy Compounds Flashcards
What is bioenergetics
The study of
energy living systems
in (environments)
and the (plants and animals) that utilize them
organisms.
How organisms manage their energy sources
What is energy
capacity to cause change
• It exists in various forms, some of which can
perform work
– Chemical energy is potential energy available for release in a chemical reaction.
• Required by all organisms
• May be Kinetic or Potential energy
• Energy can be converted from one form to another
What is k.e
• Energy of Motion
• Heat and light energy are examples
What is p.e
•
Energy
of position.
Includes
Energy stored in chemical
Bonds
What is free energy
• The free-energy change of a reaction tells us whether the reaction occurs spontaneously
• A living system’s free energy is energy that can do work when temperature and pressure are uniform, as in a living cell
What is enthalpy
tell us the heat content (energy) of a system. - delta H
What is entropy
tell us whether a process is favourable (spontaneous) ( T delta S)
Define free energy change
∆G = ∆H – T∆S
Explain a spontaneous reaction
A reaction can occur spontaneously (is favoured) only if ∆G is negative
If: ∆G is negative (-)
• the process is exergonic
• the reaction proceeds with the release of
free energy
• the reaction will be thermodynamically
favourable in the direction written
Explain a non spontaneous reaction
A reaction cannot occur spontaneously (is not favoured) if ∆G is positive
If: ∆G is positive (+)
• the process is endergonic
• an input of free energy is required to
drive the reaction
• the reaction will be thermodynamically
unfavoured
(reverse process is favoured)
• Most of these metabolic reactions are not spontaneous
•(i.e., they are accompanied by a positive change in free energy, ΔG>0) and do not occur without some other source of free energy.
• Hence, the body needs some sort of “free-energy currency,” a molecule that can store and release free energy when it is needed to power a given biochemical reaction.
What happens to spontaneity at equilibrium
A system is at equilibrium and no net change can take place if ∆G is zero
If: ∆G is zero (0)
•The process is at equilibrium
•No net flow in either the forward or the reverse direction
•Neither process is favoured
Cells are not in equilibrium; they are open systems experiencing a constant flow of materials
A catabolic pathway in a cell releases free energy in a series of reactions
What are high energy compounds
• Compounds with a high energy bond
• If the bond is hydrolysed – chemical
energy is made available
• Less favourable reactions can be driven forward
• ATP – most commonly encountered
Hydrolysis & dehydration. Exergonic or endergonic
-Hyrolysis is Exergonic
Energy Used by Cells
-Dehydration is Endergonic
Energy is restored in Chemical Bonds
Name 5 phosphorylase high energy compounds
• ATP (hydrolysis products are ADP, AMP): major energy carrier
GTP, UTP, CTP: also high energy compound
Phosphoenol pyruvate
•Creatine phosphate (energy storage In muscle cells)
Phosphorylatedcarbohydrates(e.g.glycerol3-phosphate)
3 High energy reducing power carriers
: NADPH (NAD+)
NADPH (NADP+)
• FADH, (FAD)