Cell Metabolism 1 Flashcards
What are the 6 types of reactions?
- Oxidation-reduction (e transfer)
- Ligation requiring ATP cleavage (form covalent bonds)
- Isomerisation
- Group transfer
- Hydrolytic
- Addition/removal of functional groups (make/break double bonds)
Where does glycolysis occur?
Cytoplasm
Is glycolysis aerobic?
No
What are the 2 stages of glycolysis?
- Formation of high energy compound
- Splitting
How is ATP involved in each of the 2 stages?
- Invest ATP
- Generate ATP
What reaction does glucose undergo? (reactant, product, enzyme, type)
Glucose —> Glucose-6-phosphate
- Hexokinase (use ATP)
- Group transfer
What are 2 important features of step 1?
- Irreversible so commits glucose to glycolysis
- Negative product so trapped in cell
What can G6P also be used in?
Pentose phosphate pathway
What reaction does G6P undergo?
Glucose-6-phosphate —> Fructose-6-phosphate
- Phosphoglucose isomerase
- Isomerisation
Why is F6P produced?
Can split to equal halves
What reaction does F6P undergo?
Fructose-6-phosphate —> Fructose-1,6-bisphosphate
- Phosphofructokinase (use ATP)
- Group transfer
What are the high energy compounds of glycolysis?
- Dihydroxyacetone phosphate
- Glyceraldehyde-3-phosphate
What reaction does F16BP undergo?
Fructose-1,6-bisphosphate —> Dihydroxyacetone phosphate + Glyceraldehyde-3-phosphate
- Aldolase
- Hydrolytic
Which enzyme controls the entry of sugars into glycolysis?
Phosphofructokinase
What is important about TP1 deficiency?
Only fatal glycolytic enzymopathy
What reaction does DHAP undergo?
Dihydroxyacetone phosphate —> Glyceraldehyde-3-phosphate
- Triose phosphate isomerase
- Isomerisation
What reaction does G3P undergo?
Glyceraldehyde-3-phosphate —> 1,3-Bisphosphoglycerate
- Glyceraldehyde-3-phosphate dehydrogenase (generate NADH)
-Redox and Group transfer
What reaction does 13BPG undergo?
1,3-Bisphosphoglycerate —> 3-Phosphoglycerate
- Phosphoglycerate kinase (generate ATP)
- Group transfer
What reaction does 3PG undergo?
3-Phosphoglycerate —> 2-Phosphoglycerate
- Phosphoglycerate mutase
- Isomerisation
What reaction does 2PG undergo?
2-Phosphoglycerate —> Phosphoenolpyruvate
- Enolase
- Group removal
What reaction does PEP undergo?
Phosphoenolpyruvate —> Pyruvate
- Pyruvate kinase (generate ATP)
- Group transfer
Which glycolysis reaction is dehydration?
2PG —> PEP + H2O
Which 2 reactions use ATP investment?
- G —> G6P
- F6P —> F16BP
Which 2 reactions generate ATP?
- 13BPG –> 3PG
- PEP —> P
Which reaction generates NADH?
G3P —> 13BPG
What are the 10 steps of glycolysis?
- G —> G6P
- H K - G6P —> F6P
- PG I - F6P —> F16BP
- PF K - F16BP —> DHAP + G3P
- A - DHAP —> G3P
- TP I - G3P —> 13BPG
- G3P D - 13BPG —> 3PG
- PG K - 3PG —> 2PG
- PG M - 2PG —> PEP
- E - PEP —> P
- P K
What is the overall equation of glycolysis?
Glucose + 2 NAD —> 2 Pyruvate + 2 NADH + 2 ATP
When does the PPP occur?
Anabolic reactions
Which 2 molecules are important in the PPP?
- Ribose-5-phosphate
- NADPH
When are each of the 4 modes of PPP used?
- R5P > NADPH needed
- R5P + NADPH needed
- R5P < NADPH needed
- NADPH + ATP needed
Which PPP mode is used in RBCs and why?
3
- NADPH maintains reduced glutathione (antioxidant)
What is the reaction of mode 3 of the PPP?
G6P + 12 NADP + 7 O2 —> 6 CO2 + 12NADPH + 12 H+ + Pi
What are the 2 reactions of alcoholic fermentation?
- Pyruvate —> Acetaldehyde
- Pyruvate decarboxylase (make CO2) - Acetaldehyde —> Ethanol
- Alcohol dehydrogenase (use NADH)
What are the 3 fates of pyruvate?
- Alcoholic fermentation
- Lactate production
- Acetyl CoA production
Where does alcoholic fermentation usually occur?
Yeast
What is the reaction of generation of lactate?
Pyruvate —> Lactate
- Lactate dehydrogenase (use NADH)
- Reversible
When does generation of lactate occur?
Limited oxygen
What must be a product of the 3 fates of pyruvate?
NAD+
What is the reaction of CP?
Creatine Phosphate + ADP —> Creatine + ATP
- Creatine kinase (make ATP)
- Reversible
Why must CP be used as a buffer?
ATP does not sustain muscle contraction for long enough during exercise
What is the ΔG of ATP hydrolysis?
-31 kJ/mol
What is the ΔG of CP hydrolysis?
-43.1 kJ/mol
What is the muscle contraction time for ATP vs CP hydrolysis?
1 vs 4 secs
What is the reaction of acetyl CoA generation?
Pyruvate + HS-CoA + NAD —> Acetyl CoA + CO2 + NADH
- Pyruvate dehydrogenase complex (make NADH)
Where does acetyl CoA generation occur?
Mitochondria
Which bond in acetyl CoA is most important and why?
Thioester bond
- high energy so readily hydrolysed
- allows ACoA to donate acetate
What deficiency causes Beri-Beri and why?
Thiamine (vit B1)
- cofactor in PDH complex
- can readily lose proton so becomes a carbanion that can attack pyruvate
What are the 3 symptoms of Beri-Beri?
- PNS damage
- Weak musculature
- Dec cardiac output
