3 - Metabolic pathways and ATP production I Flashcards
What are the 3 stages that take place in metabolism and where does each stage take place?
1 - Digestion
enzymes break down larger molecules into smaller molecules
takes place in the intestines
2 - Cellular metabolism 1
oxidation of small molecules within the cytosol, generating ATP and NADH
in the cytosol
3 - Cellular metabolism 2
oxidation of small molecules generated in CM 1 within the mitochondria of cells. Generates ATP and waste products.
in the mitochondria
The combustion of glucose has a relatively high activation energy. How is this overcome?
there are several enzyme-catalysed reactions with smaller activation energies, which can be overcome by enzymes and body temperature
What enzyme is used in reaction 5 of glycolysis?
trios phosphate isomerase
What enzyme is used in reaction 8 of glycolysis?
phosphoglycerate mutase
What enzyme is used in reaction 9 of glycolysis?
What types of reaction is this?
enolase
dehydration (produces a water molecule)
overall, how many ATP and NADH are produced in glycolysis?
net 2 ATP
2 NADH
Define substrate level phosphorylation
the production of ATP by the direct transfer of a high energy phosphate group from an intermediate substrate in a biochemical pathway to ADP
Define oxidative phosphorylation
the production of ATP using energy derived from the transfer is electrons in an electron transport chain
What is the intermediate during alcoholic fermentation of pyruvate?
What is the enzyme that catalyses the reaction?
What by product is produced?
acetaldehyde
pyruvate decarboxylase
CO2
What enzyme converts acetaldehyde into ethanol during alcoholic fermentation?
What else is converted in this process?
alcohol dehydrogenase
NADH H+ ———-> NAD+
Under what conditions does alcoholic fermentation take place?
yeast carries this out under anaerobic conditions
What enzyme catalyses the reaction that converts pyruvate into lactate?
What else is converted in this process?
lactate dehydrogenase
NADH H+ ———-> NAD+
Under what conditions does the generation of lactate take place?
anaerobic
occurs regularly in mammalian muscle during periods of intense exercise
High levels of lactate dehydrogenase (LDH) can be used as a diagnostic tool. What can high levels of LDH be a sign of?
- stroke
- heart attack
- liver disease
- muscle injury
- muscular dystrophy
- pulmonary infarction
What is creatine phosphate and what is it used for?
a large reservoir of phosphate, which can be used to phosphorylate ADP to ATP
What is the reaction of creatine phosphate?
What enzyme catalyses this reaction?
PCr + ADP —–> Cr + ATP
enzyme = creatine kinase
When are creatine phosphate levels in the bloodstream high?
when the muscle is damaged, it leaks into the bloodstream
What can elevated levels of creatine phosphate be used for?
- to diagnose myocardial infarction
- to determine the extent of muscular disease
- evaluate the cause of chest pain
- help discover carriers of muscular dystrophy
Where does generation of acetyl CoA occur?
in the mitochondria
What is the name of the enzyme complex used in generation of acetyl CoA?
pyruvate dehydrogenase complex
Give the overall reaction that takes place in the pyruvate dehydrogenase complex?
pyruvate + CoA + NAD+ —–> acetyl CoA + NADH + CO2
What are the 3 enzymes involved in the pyruvate dehydrogenase complex?
pyruvate decarboxylase
lipoamide reductase-transacetylase
dihydrolipoyl dehydrogenase
What are the 5 co-factors involved in the pyruvate dehydrogenase complex?
thiamine pyrophosphate (TPP) lipoamide FAD CoA NAD+
How many polypeptides are there in the pyruvate dehydrogenase complex?
60
