Citric Acid Cycle

Question 1

What is the citric acid cycle?

Answer 1

It is a series of chemical reactions to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins.

Question 2

What is the function of the citric acid cycle?

Answer 2

The function of the citric acid cycle is to harvest high-energy electrons from carbon fuels.

Question 3

What is stage 1 of respiration?

Answer 3

carbon from metabolic fuels (CHO, fats and proteins) is incorporated into acetyl-CoA during aerobic respiration

Question 4

What is stage 2 of respiration?

Answer 4

the Krebs cycle oxidizes acetyl-CoA to produce CO2, reduced electron carriers, and a small amount of ATP

Question 5

What is stage 3 of respiration?

Answer 5

the reduced electron carriers (NADH, FADH2) are re-oxidized, providing energy for the synthesis of additional ATP

Question 6

When we say electrons, we are talking about ________.

Answer 6

energy

Question 7

How are electrons captured?

Answer 7

Usually by producing NADH and FADH2

Question 8

NADH and FADH2 getting transported to the mitochondria is which stage?

Answer 8

stage 2

Question 9

Where does the citric acid cycle take place?

Answer 9

mitochondrial matrix

Question 10

The final electron acceptor of electrons is _______.

Answer 10

oxygen

Question 11

Where does oxidative phosphorylation occur?

Answer 11

In the inner mitochondrial membrane

Question 12

Do adults have brown adipose tissue?

Answer 12

no

Question 13

The _______ is impermeable to ions and most other compounds.

Answer 13

inner mitochondrial membrane

Question 14

The chemical energy used for most cellular process is carried by?

Answer 14

ATP

Question 15

The Bonds between the phosphate groups in ATP are very [high/low] energy

Answer 15

high

Question 16

When a phosphate group is [added/removed], energy is released.

Answer 16

removed

Question 17

One way carbohydrate energy is used by organisms is through the process of __________.

Answer 17

cellular respiration

Question 18

The more phosphate groups, the [less/more] energy.

Answer 18

more

Question 19

Order these from lowest energy to highest energy: ADP, ATP, AMP.

Answer 19

1. AMP
2. ADP
3. ATP

Question 20

Where can we find substrate-level phosphorylation occurring?

Answer 20

during Glycolysis and the Kreb’s Cycle

Question 21

__________ involves the physical addition of a free phosphate to ADP to form ATP.

Answer 21

substrate-level phosphorylation

Question 22

Where can we find oxidative phosphorylation occurring?

Answer 22

electron transport chain

Question 23

What happens in the electron transport chain?

Answer 23

ATP is synthesized indirectly from the creation of a proton gradient and the movement of these protons back across the membrane through the protein channel, ATP synthase

Question 24

Pyruvate freely diffuses through the __________ through the channels formed by trans-membrane proteins called ______.

Answer 24

outer membrane of mitochondria; porins

Question 25

What types of proteins are porins?

Answer 25

transmembrane proteins

Question 26

What is pyruvate translocase?

Answer 26

protein embedded into the inner membrane

Question 27

Function of pyruvate translocase?

Answer 27

it transports pyruvate from the inter-membrane space into the matrix

Question 28

Where is pyruvate produced?

Answer 28

In the cytoplasm

Question 29

What happens to the pyruvate for it to enter the TCA cycle?

Answer 29

It has to be converted into Acetyl-CoA

Question 30

How can the pyruvate pass through the impermeable inner mitochondrial membrane?

Answer 30

By pyruvate translocase

Question 31

Where is pyruvate converted into Acetyl-CoA?

Answer 31

In the matrix

Question 32

Pyruvate oxidation to acetyl-CoA is catalyzed by?

Answer 32

pyruvate dehydrogenase complex (PDH complex)

Question 33

Pyruvate oxidation is an oxidative ______ process.

Answer 33

decarboxylation

Question 34

Pyruvate oxidation is a [irreversible/reversible] reaction.

Answer 34

irreversible

Question 35

Pyruvate oxidation involves how many coenzymes?

Answer 35

5 coenzymes

Question 36

Pyruvate oxidation involves how many enzymes?

Answer 36

3 enzymes

Question 37

Pyruvate dehydrogenase is located where in the cell?

Answer 37

In the matrix of the mitochondria

Question 38

Name the coenzymes involved in pyruvate oxidation

Answer 38

``` Thiamine pyrophosphate (TPP) FAD+ NAD+ Lipoamide HS-CoA ```

Question 39

Name the vitamins involved in pyruvate oxidation

Answer 39

``` B1 - thiamine B2 - riboflavin B3 - pantothenic acid B5 - nicotinamide Lipoic acid ```

Question 40

Which step will produce ATP?

Answer 40

The conversion of Succinyl CoA to Succinate using an enzyme Succinyl CoA synthase. (step 4)

Question 41

What is equivalent to ATP?

Answer 41

GTP

Question 42

Which step will produce FADH2?

Answer 42

The conversion of Succinate into Fumarate.

Question 43

Which steps would involve the generation of NADH in the TCA cycle?

Answer 43

3 steps: Isocitrate dehydrogenase α-Ketoglutarate dehydrogenase complex Malate dehydrogenase

Question 44

How much energy do we get per NADH?

Answer 44

3 ATP

Question 45

How much energy do we get per FADH2?

Answer 45

2 ATP

Question 46

Citrate is formed from _________.

Answer 46

acetyl CoA and oxaloacetate

Question 47

What is the only cycle reaction with C-C bond formation?

Answer 47

citrate synthase

Question 48

Elimination of H2O from citrate to form C=C bond of ___________.

Answer 48

cis-aconitate

Question 49

Stereospecific addition of H2O to cis-aconitate forms?

Answer 49

isocitrate

Question 50

How many oxidation-reduction reactions take place in the citric acid cycle?

Answer 50

4

Question 51

Oxalosuccinate is decarboxylated to _________.

Answer 51

a-ketoglutarate

Question 52

Oxidative decarboxylation of isocitrate to ________.

Answer 52

a-ketoglutarate

Question 53

Succinyl-CoA Synthetase catalyzes what type of reaction?

Answer 53

Substrate level phosphorylation reaction

Question 54

What is the succinate dehydrogenase complex?

Answer 54

Complex of several polypeptides, an FAD prosthetic group and iron-sulfur clusters.

Question 55

Where is the succinate dehydrogenase complex embedded?

Answer 55

in the inner mitochondrial membrane

Question 56

Stereospecific trans addition of water to the double bond of ______ forms L-malate

Answer 56

fumarate

Question 57

Is the citric acid cycle anabolic or catabolic?

Answer 57

amphibolic (both catabolic and anabolic)

Question 58

The TCA cycle yields energy in the form of?

Answer 58

ATP

Question 59

The TCA cycle yields reducing power in the form of?

Answer 59

NADH and FADH2

Question 60

Is regulation of the TCA cycle considered a step of the TCA cycle?

Answer 60

no

Question 61

The TCA cycle is regulated by?

Answer 61

(1) Allosteric modulators (Alteration of the activity of an enzyme by means of a conformational change induced by a different molecule). (2) Covalent modification of cycle enzymes (Regulation by phosphorylation/ dephosphorylation) (3) Supply of acetyl CoA (pyruvate dehydrogenase complex)

Question 62

“Can I Keep Selling Substances For Money, Officer?” | stands for?

Answer 62

``` Can = Citrate I = Isocitrate Keep = Ketoglutarate Selling = Succinyl CoA Substances = Succinate For = Fumarate Money = Malate Officer = Oxaloacetate ```

Question 63

For every Acetyl CoA, how many ATP molecules are generated?

Answer 63

10