Metabolism Flashcards
What is autotrophic metabolism?
Organisms synthesise biomolecules from CO2
What is heterotrophic metabolism?
Organisms obtain biomolecules from food
What are catabolic pathways?
Break down of complex molecule releasing energy
What are anabolic pathways?
The use of energy to build macromolecules
How does oxidation of food differ from combustion?
- Oxidation occurs inc ells
- Combustion releases all energy as heat while oxidation releases it in small steps
- The activation energy for oxidation is lower than for combustion
What are the three stages of catabolism?
- Macromolecules breakdown
- Conversion to metabolic intermediates
- Final oxidation and ATP production
What is glycolysis?
The process of breaking down glucose into pyruvate producing ATP and NADH
What is the citric acid cycle and what occurs?
A central metabolic pathway in which acetyl CoA is oxidised to CO2 generating NADH and FADH2 for ATP production
What is oxidative phosphorylation?
A process in the mitochondria where ATP is synthesised using energy from electrons transferred to oxygen
What are the three steps for protein catabolisation?
- Proteins are denatured and broken down into amino acids
- Amino acids undergo interconversion or degradation releasing NH3 (ammonia)
- NH3 enters the urea cycle and energy is released for ATP production
What are the three steps for carbohydrate catabolisation?
- Polysaccharides are broken down into glucose
- Glucose is broken down into pyruvate via glycolysis
- Pyruvate eneters aerobic or anaerobic metabolism
What is aerobic metabolism?
Uses oxygen and produces more ATP
What is anaerobic metabolism?
Does not require oxygen and produced lactic acid or ethanol yielding less ATP
What is the primary function of the electron transport chain?
Transfer electrons from NADH and FADH2 to oxygen generating a proton gradient that powers ATP synthesis
What is the Cori Cycle?
The liver converts lactic acid back into glucose
What are the four precursor molecules needed for biosynthesis?
- Amino acids
- Sugars
- Fatty acids
- Nitrogenous bases
What happens during the digestion of carbohydrates including in ruminants?
- Enzyme breaks down polysaccharides into monosaccharides
- In ruminants fermentation helps digest cellulose
How are lipids matabolised?
- Lipases break down fats into fatty acids and glycerol
- Fatty acids undergo beta oxidation producing acteyl-coA
Why do fats yield more energy than carbohydrates?
Lipids have more hydrogen atoms per gram, leading to more ATP production via beta oxidiation
What is the urea cycle?
A liver pathway that detoxifies ammonia by converting it to urea which is excreted in urine
What are two short term energy storage forms?
ATP and NADH
What are two long term energy storage forms?
Gylcogen and triglycerides
How is metabolism regulated?
- Enzyme concentration and activity
- Feedback mechanisms
What is the key regulatory step in metabolism?
The conversion of pyruvate to Acetyl-CoA which commits it to energy production or biosynthesis
How is energy stored in ATP?
In the high energy phosphate bonds between the three phosphate groups
What is beta oxidation?
The process of breaking down fatty acids in Acetyl-CoA for ATP production
Where does beta oxidation occur?
In the mitochondria
What happens when glucose is unavailable for energy?
The liver converts fatty acids into ketone bodies for energy
What is lactic acid fermentation?
Converts pyruvate into lactic acid
What is alcoholic fermentation?
Converts pyruvate into ethanol and CO2
