Fain 52

we will review a bit at the end.What he tests on will come from 1-26 and statements on first page under 51b.
Today: pathways of glycolysis. No inborn errors known in these enzymes- if they aremissing, you die in utero.
E. Coli and man- glycolysis is the same process.
Gluconeogenesis is not the foundation of life- mammals must make glucose in liver to supply brain.
3: summary of next few days.
Pyruvate to acetyl coA is the only one-way pathway on this chart. Ethanol comes in as acetyl coA, so if 2 people are stranded, one with alcohol and one with sugar, the person with sugar lasts longer.
Anaerobic oxidation yields lactate in man.
4: 2 pyruvates from every glucose. 2ATPs to prime. Yields 4 ATPs. net:2 ATPs. Glucose to G6P isomerized to fructose 6-phosphate. Fructose can’t come in here- has to be handled in liver. rxn 2 is reversible using a phosphatase. Reversible steps are common to glycolysis and gluconeogenesis.
5: Know structure of pyruvate, acetate, lactate.
9: Know irreversible steps and Rate Limiting Step in glycolysis. PFK-1 is committed step. It is also the rate- limitng step. Hexokinase is not because product can proceed through different pathways.PFK-1 is allosterically regulated.
11: Most enzymes are inhibited by their products. When you have lots of ATP in a cell, you don’t want to make more by breaking down glucose. PFK-1 is activated by AMP. Citrate is from TCA cycle, indicating Acetyl-coA is high. These are 3 irreversible enzymes of glycolysis. Fructose 2,6 bisphosphate is a regulator to prevent futile cycling. Activates glycolysis and blocks gluconeogenesis.Dont want breakdown and synthesis at same time.
13: Aldolase splits fructose 1,6 bisphosphate.
15: no energy change in isomerization.
16: Glyceraldehyde-3-phosphate dehydrogenase used as a marker because it is in every cell. Converts aldehyde to hydroxyl group. 2Hs removed, one from water.
17: Change phosphorylation to phosphorolysis.
18: Sulfhydryl group is in active site of enzyme. NAD is essential coenzyme. Step 4: phosphorylytic attack. Ordinalily water would attack there. Active site is deep within enzyme and excludes water, but has binding site for phosphate.
25: Ferment- life without oxygen. Lactate dehydrogenase converts pyruvate to lactate. Dehydrogenates lactate to give you pyruvate.
27: Important step. Cannot go back. Get Ethanol and NAD+. Yeast does this. Good test question: If a certain child is sick and does not eat, gets hypoglycemic coma. Happy all the time- producing alcohol- problem- bleeding glucose needed for brain into alcohol. Yeast make ethanol. Can be further fermented to acetic acid.
This does not happen in people in real life- made up test question.
30: energetics.
32: Your body only gets 33% of work out to ATP production. Rest goes to generate heat.
33: Repeat slide. Know this.
Allosteric- any site except catalytic site to which something binds. Hexokinase has more than one site for binding of ATP.
35: Pyruvate comes from amino acids.
39: What biotin does.
40: Reaction involves GTP.
42: Mammals have glucose 6-phosphatase only in liver.
43: Cori cycle- lactate to liver to convert to pyruvate and glucose. Alanine cycle gets amine to liver in chronic starvation, breaking down muscle protein.
44: Cori cycle.
45: Alanine cycle. Nitrogen converted to urea in liver.
46: Substrate cycling is not the same as futile cycling.From pyruvate to glucose, need 4 ATP.
52: Why both functions on same enzyme? one function can be turned on, the other off.
Few minutes of review:
on 1-26 on handout. Most are statements of what he expects us to know.
4. What are 2 functions of pentose phosphate pathway that can be carried out by glycogenolysis.
What are 3 irreversible steps in glycolysis?
7. Which enzyme forms NADH in glycolysis? G3PdH.
8. Name 2 enzymes.
9. Where does lactate go in man vs. yeast? What happens to NADH?
11. No enzyme to bypass pyruvate decarboxylase.
12. Name steps.
13. What is role of biotin?
14 and 15- irreversible steps.
16. Why is lactate released from muscle during anaerobic exercise, alanine during starvation?
Turn back to 51b.
What form is energy captured in? ion gradients. What are they used to do? Pump substances against their gradients or make ATP.
Why can you convert creatine phosphate to ATP but not Glucose 1-p to ATP? phosphoryl potential.
Digestion in gut does what for metabolism?
What is difference between use of NADPH and NADH?
Where do the major reactions of metabolism listed occur in glycolysis? (not ligation)
How do we regulate metabolism?
1. amount substrate
2. allosteric modification or covalent modification by phosphorylation
3. synthesis and/or degradation to control the amount of enzyme
Be familiar with glycolysis and gluconeogenesis.