Citronsyrecyklussen

Question 1

components of pyruvat dehydrogenase complex

Answer 1

pyruvate dehydrogenase E1
dihydrolipoyl transacetylase E2
dihydrolipoyl dehydrogenae E3

Question 2

Aminoacids can enter this cycle as

Answer 2

acetate, malate or succinate

Question 3

Warburg effect in terms of pyruvate oxidation

Answer 3

slows down the oxidation

Question 4

How many cofactors does PDH-complex have

what is it subject to

Answer 4

5 cofactors 4 are derived from vitamines

subject to covalent modification and steric regulation

Question 5

Enzymes and coenzymes in PDH-complex

Answer 5

3 enzymes: dihydrolipoyl dehydrogenase + dihydrolipoyl transacetylase + pyruvate dehydrogenase

5 coenzymes fra hvilke vitaminer

TPP (thiamine)
NAD (niacin)
FAD (riboflavin)
CoA (pantothenate)
Lipoate

Question 6

where do TPP, FAD and lipoate bind to?

Answer 6

E1, E3 and E2

Question 7

what produces the flexible arm between E1 and E3

Answer 7

lipoate when binding to lysin at the end of E2

Question 8

what is meant by substrate channeling

Answer 8

the intermediates never leave the enzyme

Question 9

how many oxidation reactions are there in the citric acid cycle

Answer 9

4

Question 10

what does aconitase have in the active site that helps bind the substrate

Answer 10

iron-sulfur center

Question 11

Aconitase and iron homeostasis

Answer 11

regulates it when iron is depleted

Question 12

moonlighting enzymes

Answer 12

enzymes having more than one job

Question 13

types of isocitrate dehydrogenase

Answer 13

1- in mitochondria (using NAD+)

2- In the cytosol using NADP+ for anabolic processes

Question 14

when is CO2 produced in Citric acid cycle

Answer 14

from isocitrate -> alpha ketoglutarate

from alpha ketoglutarat -> succinyl-CoA

Question 15

what metal does isocitrate dehydrogenase have at the active site

Answer 15

Mg2+

Question 16

phosphorylases?

Answer 16

Phosphate groups attacking the cleavage points

Question 17

ligase

Answer 17

condensation reactions using energy

Question 18

what can malonyl-CoA inhibit

Answer 18

carnitin acyltransferase I and succinate dehydrogenase

Question 19

the conversion of malate –> oxaloacetat

Answer 19

is very endergonic but coupled with very exergonic citrate formation

Question 20

what is an amphibolic pathway

Answer 20

pathway that is anabolic and catabolic

Question 21

what does avidin do

Answer 21

binds to biotin and prevents its absorption in the intestines

Question 22

anaplerotic reactions in glycolysis

Answer 22

formation of oxaloacetate or malate from pyruvate or PEP

Question 23

By what and how is PDH activated?

Answer 23

by phosphoprotein phosphatase, by removing a phosphoryl group

Question 24

where is the citric acid cyle regulated?

Answer 24

citrate synthase
pyruvate dehydrogenase
a-ketoglutarat dehydrogenase + aconitase
transport of pyruvate into mitochindria using (MPC) mitochondrial pyruvate Carrier

Question 25

which enzyme is membrane bound

Answer 25

succinate dehydrogenase

Question 26

pyruvate , lactate and acetyl-CoA are maintained at ……

Answer 26

steady state level