Cell Metabolism Flashcards
What does glycolysis produce?
2 x Pyruvate
2 x NADH
2 x Net ATP
What reaction is irreversible and commits the cell to glycolysis?
The conversion of glucose to glucose - 6 - phosphate
What is the complete reaction steps of glycolysis?
Glucose
Glucose - 6 - Phosphate
Fructose - 6 - Phosphate
Fructose - 1,6 - Bisphosphate –> dihydroxyacetone phosphate and
Glyceraldehyde - 3 - Phosphate
1,3 - Bisphosphoglycerate
3 - Phosphoglycerate
2 - Phosphoglycerate
Phosphenolpyruvate
Pyruvate
Which step of glycolysis does phosphofructokinase control?
The conversion of fructose - 6 - phosphate into fructose - 1,6 - bisphosphate
What does TPI stand for?
Triose phosphate isomerase
What does hexokinase catalyse?
The conversion of glucose into glucose - 6 - phosphate
What is the only glycolytic enzymopathy which is fatal?
Deficiency in TPI
Which reactions produce ATP?
The conversion of 1,3-Bisphosphoglycerate into 3-phosphglycerate and phosphenolpyruvate into pyruvate
What do kinases do?
Transfer phosphate groups to molecules
Which step in glycolysis needs NAD+?
Glyceraldehyde - 3 - phosphate into 1,3 - bisphosphoglycerate
Which steps of glycolysis require ATP?
Glucose -> glucose - 6 - phosphate
Fructose - 6 - phosphate -> Fructose - 1,6 - bisphosphate
Does glycolysis need oxygen to occur?
No - it is anaerobic
Where does glycolysis occur?
In the cytoplasm
Why are high energy phosphate groups added to some of the substrates involved in glycolysis?
Adding the phosphate groups makes them easier to split as they are more reactive
What are the three fates of pyruvate?
- Lactate generation
- Acetyl CoA Production
- Alcohol fermentation
What enzyme is needed to generate Acetyl CoA from pyruvate?
Pyruvate dehydrogenase complex
What does pyruvate dehydrogenase needed as a cofactor?
Thiamine
What does a deficiency in thiamine result in?
Beri - Beri
This is a condition which leads to muscle weakness
How is pyruvate converted into lactate?
Using lactate dehydrogenase complex
What does the fermentation of alcohol and lactate production both regenerate?
NAD+ - this is needed for glycolysis to continue occurring
What happens to the Acetyl CoA that is produced?
It enters into the Krebs Cycle
What are the stages of the Krebs Cycle?
Acetyl CoA combines with oxaloacetate to make Citrate
Then Alpha - keto glutarate
Succinyl CoA
Succinate
Fumerate
Malate
What does the Krebs cycle produce?
2 x CO2
1 x GTP
3 x NADH
1 x FADH
What reaction in the Krebs cycle produces FADH?
The conversion of succinate to fumerate
Where does the krebs cycle occur?
The mitochondrial matrix
What is a transamination reaction?
the process of removing an amine group from one amino acid and transferring it to a ketoacid, producing another ketoacid and amino acid
What are the seven things which can be produced from transamination reactions?
Pyruvate
Succinyl CoA
Acetoacetyl CoA
Acetyl CoA
Oxaloacetate
Alpha Keto Glutarate
Fumerate
Explain Alcoholic Fermentation of Pyruvate
Pyruvate is converted into Acetaldehyde using pyruvate decarboxylase. Then using alcohol dehydrogenase is used to convert the acetaldehyde into ethanol
Why is it essential that NAD+ is regenerated?
Needed for dehydrogenation of glyceraldehyde-3-phosphate to produce ATP
Allows glycolysis to occur anaerobically
What is the Warburg effect?
Mutations in genes of Fumerase, Succinate, Isocitrate Dehydrogenase, decreases Kreb’s Cycle activity which enhances anaerobic glycolysis
What are glucogenic amino acids?
Ones whose carbon skeletons are used to make glucose
What are ketogenic amino acids?
Amino acids which when they are broken down, form ketone body precursors like Acetyl CoA
During fasting, which type of metabolism dominates?
fat metabolism, resulting in the production of ketone bodies
What happens when the levels of Acetyl CoA is not equal to Oxaloacetate?
The excess Acetyl CoA is used to make ketone bodies
What are the names of the three ketone bodies?
Acetone, Acetoacetate and 3 - Beta - Hydroxy Butyrate
Why can ketone bodies be utilised by the brain but fatty acids cannot?
Fatty acids can’t cross the blood brain barrier
What is the purpose of the Glycerol Phosphate Shuttle
To carry electrons from NADH across the matrix - this is because the mitochondrial matrix is impermeable to NADH
Where in the body is the Glycerol-Phosphate Shuttle used?
brain and skeletal muscle