TCA

Question 1

label the three starting reagents and two products from Citric acid Cycle during early catabolism

Answer 1

starting reagents: fatty acid, amino acid, monosaccharides

two products: ATP (energy) and molecular building blocks

Question 2

label in the boxes for early catabolism stage.

Answer 2

From left to right: monosaccharides, glycolysis, pyruvate, pyruvate dehydrogenase complex, coenzyme A, and Acetyl group

Question 3

What happens in this step in the picture below?

Answer 3

In the citric acid cycle, acetyl-CoA gets oxidized to CO₂ with the concomitant reduction of NAD⁺ and ubiquinone (Q)

Question 4

What are tthe two main purposes in citric acid cycle?

Answer 4

1. Increase the cell’s ATP producing potential
2. Provide the cell wiht precursors that can be used to build a variety of molecules, depending on the cell’s needs.

Question 5

Where does prokaryotic cell perform citric acid cycle?

Answer 5

in cytosol

Question 6

Where does the eukaryote perform citric acid?

Answer 6

Eukaryotic cells perform the citric acid cycle in the mitochondrial matrix.

Question 7

Which compound traverse the mitochondrial membrane to connect the glycolytic pathway with the citric acid cycle?

Answer 7

Pyruvate is the product of glycolysis that is transported across the mitochondrial membrane. Within the mitochondrial maitrix, the pyruvate underogoes further oxidation as it is converted to acetyl-CoA by the pyruvate dehydrogenase complex

Question 8

What is the purpose of having Acetyl-CoA?

Answer 8

It enters the critric acid cycle to inititate the circular reaction pathway

Question 9

write the net reaction for citric acid cycle.

Answer 9

From top left to top right to bottom right to bottome left:

Acetyl-CoA, Oxidized electron carriers, nucleoside diphosphate, inorganic phosphate, (yield), nucleoside triphosphate, reduced electron carriers, CO2, and coenzyme

Question 10

fill in the blank for the citric acid cycle that is catabolic: molelcules are broken down to serve energy needs of the cell

Answer 10

From top right, clockwise:

citrate, isocitrate, α-ketoglutarate, succinyl-CoA, succinate, fumarate, malate, oxaloacetate

Question 11

fill in the blank for the citric acid that are anabolic

Answer 11

from top right, clockwise:

citrate, fatty acids/cholesterol, isocitrate,α-ketoglutarate, amino acids (nucleotides), succinyl-CoA, heme, succinate, fumarate, malate, pyruvate, oxaloacetate, glucose.

green fonts or bolded are intermediates in synthesis

Question 12

Explain in details for the red/yellow arrows in the anabolic citric acid.

Answer 12

from top right, clockwise:

• citrate supplies carbon atoms used for fatty acid and cholesterol synthesis
• alpha-ketoglutarate is used for synthesis of amino acid glutamate
• succinyl-coA is used for synthesis of heme, the molecule in hemoglobin that carries oxygen
• malate is decarboxylated by the malic enzyme to produce pyruvate
• oxalogacetate is a precursor of mono-saccharides (such as glucose)

Question 13

Which of the CAC intermediates are considered to be gluconeogenic?

Answer 13

Oxaloacetate is directly gluconeogenic. However, all of the citric acid cycle intermediates are indirectly regarded as gluconeogenic. Any intermediate that can be converted by the cycle to oxaloacetate is ultimately gluconeogenic.

Question 14

What molecules are degraded to acetyl-CoA? see image.

Answer 14

palmitate

lysine

glutamate

glucose