Citric acid cycle

Question 1

is the citric acid cycle involved in catabolic & anabolic reactions

Answer 1

yes

called amphibolic pathway

Question 2

what 2 substances can acetyl CoA be produced from?

Answer 2

from fatty acids or pyruvate

Question 3

what is another name for the citric acid cycle?

Answer 3

Krebs cycle or Tricarboxylic acid cycle.

Question 4

Where does the citric acid cycle occur?

Answer 4

in the mitochondrial matrix

Question 5

what is the difference between citric acid cycle and glycolsis

Answer 5

Krebs cycle/tricarboxylic acid cycle produces large amounts of ATP as opposed to glycolysis which produces 2ATP

Question 6

what products does the citric acid cycle form?

Answer 6

NADH & FADH2

Question 7

describe the first process of the enzyme E1 in pyruvate dehydrogenase complex

Answer 7

E1: decarboxylation of pyruvate

TPP reacts with pyruvate and removes carbon in the form of CO2

Question 8

describe the first process of the enzyme E2 in pyruvate dehydrogenase complex

Answer 8

acetyl group is transferred to CoA

Question 9

describe the first process of the enzyme E3 in pyruvate dehydrogenase complex

Answer 9

lipolysn is recycled which releases 2 electrons in the form of 2 hydrogens

this id done through reduction of FAD

Question 10

what is the end product in the pyruvate dehydrogenase complez?

Answer 10

2NADH + 2 acetyl CoA

Question 11

explain the regulation & control of pyruvate hydrogenase (PHD) in the transition stage if the cell has enough energy and when the cell doesnt

Answer 11

enough energy: inhibits PDH (stimulating PDH kinase inhibits PDH)

when cell lacks energy: stimulate PDH(inhibition of PDH kinase stimulates PDH)

Question 12

what is PDH kinase? & how does it do its job

Answer 12

PDH is an enzyme that inhibits PDH E1 by putting a phosphate on it

Question 13

What is isocitrate dehydrogenase ?

Answer 13

is an enzyme which converts isocitrate to alpha-keto

Question 14

Explain the point of control and regulation of Isocitrate dehydrogenase in Krebs Cycle

Answer 14

When the cell has energy : it inhibits isocitrate DH through increase in NADH & ATP

when cell needs energy: stimulates isocitrate DH through increase in ADP

Question 15

Explain the point of control and regulation of α-ketoglutarate dehydrogenase during Krebs Cycle

Answer 15

cell has enough energy: inhibts alpha-keto DH through increase in NADH, ATP and Succinyl CoA

cells needs more energy: stimulate alpha-keto through increase in Ca+

Question 16

How do the control and regulation points during Krebs cycle allow re-direction of cellular response ?e.g if isoctitrate & alpha-keto become inactive

Answer 16

when isocitrate dehydrogenase is inactive it causes a build up of citrate which then moves into the cytoplasm causing phosphofructosekinase to stop glycolysis

when alpha-keto is inactive it causes build up of alpha-keto which changes its use to production of amino acids

Question 17

Citric cycle is an amphibolic pathway, what does this mean?

Answer 17

it is both anabolic and catabolic processes

Question 18

how does pyruvate convert into Oxaloacetate, what enzyme

Answer 18

Using pyruvate carboxylase

Question 19

Describe how can we can replenish oxaloacetate when the muscle cells require ATP

Answer 19

pyruvate carboxylase is only present with Acetyl CoA so increase in acetyl CoA will generate oxoloactate & using in krebs cycle.

Question 20

what does oxaloactate and acetyl CoA produce ?

Answer 20

citrate (6carbon molecule)

oxoacltate is a 4 carbon molecule

Question 21

how is oxaloactate formed

Answer 21

pyruvate using carboxylase