Introduction to Metabolism Flashcards
Define metabolism
Mechanisms which couple the demand for energy with the fuel supply
What do all physical process require and how is it generated?
- All physical processes require energy
- Fuel/food is digested and absorbed to generate energy for cellular activities
How can metabolic pathways be divided?
- Catabolism - degradation of molecules to release energy
- Anabolism - synthesis of new molecules to store energy
Describe the three stages of metabolism
Stage 1
Digestion in the GI tract - absorption and transport in the blood
Stage 2
In the cell cytoplasm:
Anabolic- nutrients built into storage molecules
Catabolic - nutrients/storage molecules broken down
Stage 3
In mitochondria:
Catabolism requiring oxygen to completely breakdown food and generate ATP
What are the two nutritional stages
- Absorptive - fed
- Post absorptive - fasting
Energy is stored in the absorptive state and released in the postabsorptive
What are the key coenzymes involved in redox reactions?
- Nicotinamide adenine dinucleotide (NAD) – derived from Vit B3/Niacin
- Flavin adenine dinucleotide (FAD) – derived from Vit B2/riboflavin
At what stages does transfer of H+/e- take place?
- Glycolysis
- Citric acid cycle/Krebs cycle/Tricarboxylic acid cycle
- Oxidative phosphorylation
How is energy stored?
In phosphate in phosphate bonds of ATP
How is energy from catabolism used?
Energy produced by catabolism is used to drive anabolism and other energy requiring processes
What is gibbs free energy?
- Energy in biological systems is measured using Gibbs free energy
- It gives an indication of whether a reaction generates energy or requires input of energy in order to take place
What are the types of enzyme reaction?
- Exergonic - Favourable
- Releases more energy than input
- Endergonic - Unfavourable
- Requires more energy input than it yields
