Chapter 11: Catabolism: Energy Release and Conservation PART 3 (slides 21-23) Step 2 --> Pyruvate to CO2 by TCA Cycle

From glucose to pyruvate, in all pathways, how many carbon skeletons have we learned about? What are they? What pathway do we see them in?

-a total of 8 carbon skeletons when looking across EMP, ED, and PPP

-G6P, F6P, G3P, ribose-5-phosphate, E4P, 3-phosphoglycerate, PEP, pyruvate

-EMP we see: G6P, F6P, G3P, 3-phosphoglycerate, PEP, and pyruvate

-ED we see: G6P, G3P, 3-phospglycerate, PEP, and pyruvate (main difference is no F6P is produced, but instead KDPG which is not a CS)

-PPP we see: G6P, ribose-5-phosphate, E4P, F6P, G3P, and pyruvate (G3P ---> pyruvate follows EMP reactions)

TCA cycle is known as:

Tricarboxylic Acid Cycle

Other terms for TCA include:

Krebs Cycle or Citric Acid Cycle

TCA cycle is common in what microorganisms

aerobic bacteria, free-living protozoa, most algae, and fungi

TCA is the source of _______ for use in biosynthesis?

carbon skeletons

How many carbon skeletons come from TCA?

4

TCA cycle is found where in prokaryotes? Eukaryotes?

-prokaryotes=cytoplasm

-eukaryotes=matrix of mitochondria

What carbon skeleton goes into the TCA cycle to start it?

Pyruvate

When pyruvate enters TCA cycle, how many NADH's are generated? What carbon skeleton is in turn made?

1 NADH

Acetyl CoA

Acetyl CoA is the:

first step in TCA, NOT pyruvate

From pyruvate to acetyl CoA, what is lost?

1 carbon

Acetyl-CoA had what kind of bond?

high energy thioester bond

What oxidized and cleaves the pyruvate to make Acetyl CoA + CO2?

PDH

PDH=

pyruvate dehydrogenase complex

Hydrolysis of the thioester bond of Acetyl-CoA yields?

a lot of energy

From acetyl CoA, it goes from 2 carbons to? This is the start of what stage of the TCA cycle?

6 carbons (citrate); 6 carbon stage (what makes it go from 2 to 6 will be later in the slides)

Citrate well eventually be oxidized to what carbon skeleton? How many NADH's are generated? What is lost?

alpha-ketoglutarate; 1 NADH; 1 carbon lost

Citrate---->intermediates--->alpha-ketoglutarate takes the TCA cycle from the 6 carbon stage to the? Why?

5 carbon stage; because it lost a carbon to make alpha-ketoglutarate

alpha-ketoglutarate then makes what carbon skeleton? How?

Succinyl-CoA; by generating 1 NADH and losing a carbon

alpha-ketoglutarate--->Succinyl-CoA generates how many NADH? Loses? Takes the TCA cycle from the 5 carbon stage to the?

-1 NADH

-loses 1 carbon

-5 carbon stage to the 4 carbon stage

Succinyl-CoA has what kind of bond?

a high energy thioester bond

Succinyl-CoA will make the next carbon skeleton which is what?

Oxaloacetate

Succinyl-CoA to what intermediate will result in the production of 1 ATP?

Succinate

Succinate to what intermediate will produce 1 FADH2?

Fumarate

Oxaloacetate is the carbon skeleton that take what other carbon skeleton from 2 carbons to 6 carbons?

Acetyl-CoA

Between fumarate and the carbon skeleton oxaloacetate, how many NADH do we see being generated?

1 NADH

The NADH that was generated will go where? FADH2?

both will go to the ETC

In total, how many NADH's were generated? How many FADH's were generated? How many ATPs were produced? How many carbons are lost?

-3 NADHs

-1 FADH2

-1 ATP

-2 carbons lost

The TCA cycle is primarily divided up into two phase called?

Push and pull phase

The push phase is started by what carbon skeleton? What carbon skeleton is produced in the push phase?

Acetyl-CoA; alpha-ketoglutarate and succinyl-CoA

The pull phase is started by what carbon skeleton? What carbon skeleton is produced in the pull phase?

Succinyl-CoA; oxaloacetate

How many NADH's/FADH2's/ATPs are produced and how many carbons are lost in the push phase? Pull phase?

Push phase: 2 NADH, 0 FADH2, 0 ATP, loss of 2 carbons

Pull phase: 1 NADH, 1 FADH2, 1 ATP, loss of zero carbons

PER ONE ROTATION. This means 1 pyruvate is going through this. Remember you have two pyruvates at the end of glycolysis, so this happens twice, so double the numbers if needed.

What is the main purpose of the TCA cycle?

to fully oxidize your energy source