21-Metabolism and Glucose Flashcards
What do cells use energy for?
Perform mechanical work
Synthesise molecules
Transport ions and molecules inside and between cells
How do we produce ATP?
Oxidation of food produces hydrogen and electrons
These are transferred to nucleotides
Reduced nucleotides fuel ATP production
What is glycolysis?
The pathway where the energy from glucose is harvested to generate NADH and ATP
Where does glycolysis take place?
Cytoplasm
What is the first stage of glycolysis?
Glucose- fructose 1,6-diphosphate which uses two ATP molecules
What is the key regulatory enzyme used in glycolysis?
Phosphofructokinase
What happens during the cleavage phase of glycolysis?
The 6C sugar becomes two 3C sugars (glyceraldehyde 3-phosphate)
What happens during the energy generation phase?
The two 3C sugars is oxidised by dehydrogenase with each one producing a NADH
Phosphorylation will produce another 2 ATP
The enzyme enolase will be inhibited by fluoride
Phosphorylation again producing another 2 ATPS
Two pyruvate molecules produced
What are the overall net results of anaerobic glycolysis?
Two molecules of NADH
Two molecules of ATP
Two molecules of pyruvate
What happens when oxygen is in limited supply?
Pyruvate is reduced to lactate (lactic acid)
What is oxygen debt?
Amount of extra oxygen required to remove the harmful effects of anaerobic respiration
What happens as a result of lactic acid?
Lung/heart problems that cause hypoxia
Low blood pressure leads to poor tissue perfusion with blood, so oxygen doesn’t get into tissues
Both these lead to anaerobic resp and lactic acidosis
What happens to pyruvate in well- oxygenated cells?
Pyruvate is transported from the cytoplasm into the mitochondria by specific membrane transporter
Pyruvate is then irreversible oxidatively decarboxylated to CoA
What is another name for the krebs cycle?
The citric acid cycle (TCA cycle)
What are the 8 steps of the krebs cycle?
- Acetyl CoA added to oxaloacetate (4C) to form citrate (6C)
- Citrate becomes isocitrate (6C)
- isocitrate becomes alpha-ketoglutarate (NADG and CO2 removed)
- alpha-ketoglutarate (5C) becomes succinyl-CoA (4C) (NADG and CO2 removed)
- Succinyl- CoA becomes succinate (GTP removed)
- Succinate becomes fumarate (FADH2 removed)
- Fumarate becomes malate (NADH removed)
- Malate becomes oxalocetate
