Mol Lecture #29 Flashcards
Review of Glycolysis
- 10 steps total, 1st 5 (energy requiring), last steps, energy leaving
- (1) requiring the energy of ATP molecules
- (2) Total of 4 ATP produced in the energy releasing step and 2 NADH
- Basics of implicit outputs
Reactions 3 & 6
- Step 3-
→ Fructose-6-phosphate is phosphorylated by phosphofructokinase to give fructose 1.6 bisphosphate. (Burn ATP to catalyze the reaction) (1 of the 2 examples where we actually require energy) - Step 10-
→ Phosphoenolpyruvate dephosphorylated to give pyruvate by pyruvate kinase. (*ATP generated by substrate level phosphorylation)
Reactions
- 1 and 3 are essential for substrate phosphorylation
- Gp3 is important
- Step 10: pyruvatekinase makes pyruvate
- Going from a 6-carbon molecule to a 2 3-carbon molecule.
Regulation of glycolysis
- Regulated by its products and reactants in an allosteric (binding outside of the active site- increasing or decreasing the activity of the enzyme (forcing conformational shifts)) manner
Regulation of glycolysis: ATP
→ regulating negatively
→ Thinking about metabolism and balancing metabolites (not about burning all the glucose you can)
Regulation of glycolysis: ADP
→ regulating positively
→ Thinking about converting our ratio of ADP to ATP by running the process faster ( ATP is a product of glycolysis and the downstream aftermath of glycolysis (Pyruvate kinase?))
Mitochondria p.1
- Double membrane
- Outer membrane
Inner membrane: inside the inner membrane is the mitochondrial matrix
→ between the two is the inter-membrane space
Mitochondria p.2
- Mitochondria contain their DNA and use mitochondrially encoded proteins and nuclear-encoded proteins to function. (A lot of DNA in the mitochondria floats over to the nucleus→ Proteins are made in the nucleus, and then the proteins flow over to the mitochondria)
Pyruvate oxidation takes place in
- 1) Pyruvate oxidation in the citric acid cycle occur in the mitochondrial matrix
Oxidative phosphorylation takes place in
- 2) Oxidative phosphorylation occurs in the mitochondrial matrix and across the inner membrane
Pyruvate oxidation and the citric acid cycle
- Oxidize pyruvate to an acetyl group, which is attached to CoA to enter the CAC (citric acid cycle) by being bound to a molecule called oxaloacetate
- During this whole process: carbons equivalent to the 3 in pyruvate are lost as CO2, 4 NADH are made, 1 ATP is made, and 1 FADH2 (like NADH).
- Lots of different parts of this are happening in tandem
Pyruvate Oxidation
- Transport pyruvate into mitochondria by pyruvate transporter.
- Pyruvate (3C) is oxidized to form an acetyl group (2 C) that will then be transferred to the nucleotide-based molecule coenzyme A (CoA).
→ Reduce NAD to NADH
→ Lose 1 C as CO2 - What is doing this? Pyruvate oxidation is performed by a multi-enzyme complex.
Citric Acid Cycle (Overview)
-Acetyl-CoA is the input (2C)
- 8 reactions in a cycle (Not linear)
CAC ( Whole thing doesn’t really matter)
- Isocitrate reduces NAD to NADH + H+
- At step 4 we use CoA, and probably won’t use it again
- Point: multiple reactions and enzymes
CAC Reaction 1: Important
- Citrate synthase (enzyme) joins oxaloacetate with acetyl CoA to form citric acid (and CoA is released- released to be used again (perhaps later in the CAC))
