Cell Metabolism 1 Flashcards
What are the general types of metabolic pathways?
Catabolic and Anabolic
Define a catabolic reaction
Pathways release energy and involve the breakdown of molecules
Define an anabolic reaction
Pathways require energy and are involved in the synthesis of complex molecules from simpler molecules
How do you classify monosaccharides? Give an example
They’re classified according to the number of carbons they contain in their backbone structures.
Example:
1) Glucose which has 6 carbons are classified as hexoses.
2) Ribose which has 5 carbons are classified as pentoses.
Define oxidative metabolism
A chemical process in which oxygen is used to make energy from carbohydrates, also called aerobic metabolism, aerobic respiration and cell respiration.
What are the two functions of oxidative catabolism of glucose?
1) The production of ‘free energy’ in the form of ATP
2) The production of intermediates from glycolysis and the TCA cycle to provide material for other metabolic pathways
What is the chemical equation of aerobic respiration?
C6H12O6 + 6O2 —-> 6CO2 + 6H2O
What is the standard free energy change (ΔG0’) for aerobic respiration and how can this energy be used?
-2834 KJ mol^-1 (KJ/mol). This energy can be used in the form of ATP to meet the body’s requirements.
How does biology use all the energy from aerobic respiration?
Since -2834 Kj mol^-1 is too much energy for the cell to use at once, it uses a controlled release approach in which each enzyme performs a small step hence multiple steps are required thus forming a metabolic pathway.
What happens to the energy released from fuel oxidation (aerobic respiration) that is not used for work?
It is transformed into and released as heat
How do we characterize a metabolic pathway?
We use the changes in Gibbs free energy to characterise individual steps along the pathway
Why follow the change in energy of a system?
1) Life requires energy hence that should be the main focus
2) Before all of the structural biology techniques, you could use this approach to generate reliable results without the need to know the molecular details
3) Individual values are additive allowing for a global overview
4) It can be applied to all metabolic pathways
5) It allows historically determined data to still be used in comparative studies
Define ΔG°´- (Delta G zero prime)
The change in Gibbs free energy at pH 7 under standard conditions.
It provides information about what happens to the free energy (energy available to do work) during a chemical/biological reaction. The amount of free energy available to do work is related to the difference in energy levels between the products and reactants
Define ΔG° - (Delta G zero)
The change in Gibbs free energy at pH 0 (1M [H+]) under standard conditions
What can the value of ΔG°´(Delta G zero prime) tell us
If ΔG°´is negative, free energy is released and the reaction is said to be exergonic
If ΔG°´ is positive, free energy is absorbed and is said to be endergonic
