Cellular Respiration Flashcards
what is cellular respiration?
Cellular Respiration is the metabolic process that transforms glucose into ATP in order to readily access its energy. It takes place in the cytosol and the mitochondria.
what are the 5 principles of metabolic pathways?
○ Complex transformations occur in a series of separate reactions
○ Each reaction is catalysed by a specific enzyme
○ Many metabolic pathways are similar in all organisms
○ In eukaryotes, metabolic pathways are compartmentalised in specific organelles
○ Key enzymes can be inhibited or activated to alter the rate of the pathway
what are the steps of cellular respiration and where do they occur?
- Glycolysis- cytosol
- Pyruvate Oxidation- mitochondrial matrix
- Citric Acid Cycle- mitochondrial matrix
- Electron Transport Chain- inner mitochondrial membrane
what is the equation for cellular respiration?
C6H1206 + 6O2 –> 6CO2 + 6H2O
what happens in glycolysis?
- 6 carbon sugar (glucose) is converted into fructose-1,6-biphosphate by enzymes such as phosphofructokinase-1 and hexokinase.
- These are then cleaved into 2 3 carbon sugars, from which, glyceraldehyde-3-phosphate is converted into pyruvate.
- Each 3 carbon molecule is converted, therefore producing 2 pyruvate for every glucose molecule.
- Pyruvate is then shuttled across the mitochondrial membrane to undergo pyruvate oxidation.
- 2 ATP used: 4 ATP produced = 2 NET ATP
2NAD+ 4E- +4H+ –> 2NADH +2H+ (NAD+ is reduced) electron acceptor
All 10 steps have a different enzyme catalysing it.
what is the purpose of glycolysis?
The purpose of glycolysis is to convert glucose into pyruvate
what are the two main steps in glycolysis?
Energy investment phase
Energy payoff phase
what happens in the energy investment phase?
- Glucose is converted into fructose-1,6-biphosphate, by phosphofructokinase
- Then cleaved into glyceraldehyde-3-phosphate.
- Uses 2 ATP to do this
what happens in the energy payoff phase?
- glyceraldehyde-3-phosphate (G3P) is converted into pyruvate
- Produces 2 ATP per G3P molecule (therefore 4 overall)
- Converts 2NAD+ to NADH (one for each)
how is glycolysis regulated?
Glycolysis is regulated through the activation or inhibition of phosphofructokinase. It is activated by ADP/AMP and inhibited by ATP
There is lots of ADP when there is no ATP, therefore allowing ATP to be produced by allowing glycolysis to occur
When there is too much ATP/sufficient, then this inhibits the reaction and stops more being made
This is how it is restricted
what is anaerobic respiration?
anaerobic fermentation occurs when there isnt sufficient oxygen for aerobic respiration. It occurs in order to recycle NAD+ from NADH in order to continue transforming glucose into ATP.
describe lactic acid fermentation
Glycolysis produces pyruvate, 2ATP and 2NADH. In order to recycle the NADH to keep producing ATP, pyruvate is converted into lactate in multicellular organisms. Lactate can build up and be a toxin, therefore it is important to break it down
describe alcoholic fermentation
Glycolysis produces pyruvate, 2ATP and 2NADH. In order to recycle the NADH to keep producing ATP, pyruvate is converted into ethanol and carbon dioxide in unicellular organisms + plant cells. Alocohol can build up and be a toxin, therefore it is important to break it down
pyruvate decarboxylase converts pyruvate to acetaldehyde and then it is durther reduced to ethanol by alcohol dehydrogenase
describe pyruvate oxidation- what is it and where does it occur?
occurs in the mitochondrial matrix
- Pyruvate is oxidised to acetate and CO2
- Acetate binds to coenzyme A to form acetyl CoA
- this process is catalysed by pyruvate dehydrogenase
- 2NAD+ to NADH
what is the purpose of pyruvate oxidation?
The purpose is to convert pyruvate into acetyl CoA to be used in the TAC
