2 The TCA cycle

Question 1

There are three main materials which can be converted to enter the TCA cycle - what are they?

Answer 1

Glucose

Amino Acids

Fatty Acids

Question 2

In order for cofactors to be used in the electron transport chain, what process do they need to undergo?

Answer 2

Reduction

Question 3

What monomer forms the nitrogenous base of ATP?

Answer 3

Adenine

Question 4

What kind of bonds hold the second and third phosphate groups in the ATP molecule?

Answer 4

High energy Anhydride linkages

Question 5

The normothermic condition of the body cause the ATP yield to be higher or lower than that which is recorded in laboratory experiments?

Answer 5

Higher

Question 6

What is the function of High energy anhydride linkages in ATP?

Answer 6

Linkage of phosphate groups

Question 7

To which complex of the electron transport chain does FADH deliver electrons?

Answer 7

II

Question 8

To which complex of the electron transport chain does NADH deliver electrons?

Answer 8

I

Question 9

How many protons are pumped through complex II of the electron transport chain?

Answer 9

0

Question 10

What set of reactions constitue the final common pathway of all major nutrients in the body?

Answer 10

TCA cycle

Question 11

Where does the TCA cycle take place?

Answer 11

In the mitochondrial matrix

Question 12

The TCA cycle can both catabolise and anabolise compounds, how is this charachteristic described?

Answer 12

Amphibolic

Question 13

The TCA cycle is amphibolic, what does this mean?

Answer 13

The TCA cycle can anabolise and catabolise

Question 14

What is the starting point of the TCA cycle?

Answer 14

Oxaloacetate

Question 15

What is the ending point of the TCA cycle?

Answer 15

Oxaloacetate

Question 16

What fuel molecule is required to initiate the TCA cycle?

Answer 16

Acetyl CoA

Question 17

In the TCA cycle, what molecule is reacted with oxaloacetate to form citrate?

Answer 17

Acetyl CoA

Question 18

How much ATP is directly produced in the TCA cycle?

Answer 18

None

Question 19

Does the TCA cycle directly produce ATP?

Answer 19

No

Question 20

What molecules enter the TCA cycle for the purpose of receiving electrons?

Answer 20

NAD⁺

FAD⁺

Question 21

What process is associated with the steps in the TCA cycle where CO₂ is produced?

Answer 21

Reduction of NAD⁺ to NADH

Question 22

What ATP equivalent molecule is produced during the TCA cycle?

Answer 22

GTP

Question 23

In addition to one GTP, how much ATP can be produced by the electrons yielded by the TCA cycle?

Answer 23

9

Question 24

Including GTP, what is the equivalent yeild in ATP produced by one revolution of the TCA cycle?

Answer 24

10

Question 25

When glucose is metabolised, how many times will the TCA cycle operate?

Answer 25

Twice

Question 26

What are the products of one complete revolution of the TCA cycle?

Answer 26

2x CO₂ 3x NADH 1x FADH 1x GTP

Question 27

Why must the TCA cycle end at Oxaloacetate?

Answer 27

In order to receive Acetyl CoA

Question 28

Enzymes of the Dehydrogenase type are associated with what action?

Answer 28

Electron release | (*Electron uptake by NADH / FADH*)

Question 29

**Regulatory actions** occur **early** or **late** in the TCA cycle?

Answer 29

Early

Question 30

**High levels** of what molecule **inhibit conversion** of Pyruvate to Acetyl-CoA?

Answer 30

NADH

Question 31

In addition to energy, what else is produced by the TCA cycle?

Answer 31

Metabolic intermediates

Question 32

Why is fermentation important for the continuation of the TCA cycle?

Answer 32

Replenishment of the NAD⁺ and FAD⁺ pool

Question 33

In addition to energy production, what other process occurs within the mitochondrial matrix?

Answer 33

Biosynthesis

Question 34

Why are erythrocytes unable to gain energy from fats?

Answer 34

Erythrocytes lack mitochondria

Question 35

How does NADH and FADH exit the mitochondrial matrix in order to act on the proton pumps?

Answer 35

Via the shuttles

Question 36

Which shuttle of the mitochondrial inner membrane allows uptake of NADH produced during glycolysis?

Answer 36

Glycerol Phosphate shuttle

Question 37

Which of these reducing equivalent shuttles provides the highest yield of ATP? Glycerol Phosphate Malate-Aspartate

Answer 37

Malate-Aspartate

Question 38

In what structure of the mitochondria does oxygen accept electrons?

Answer 38

At the proton pumps Complex I, III, IV

Question 39

To what does the *Acetyl* component of Acetyl-CoA refer?

Answer 39

Carriage of two carbons

Question 40

What is the name of a coenzyme which delivers two carbons to the TCA cycle?

Answer 40

Acetyl CoA

Question 41

A **High Energy Thioester** bond is located in what area of an Acetyl CoA molecule?

Answer 41

Attaching the two carbon atoms

Question 42

What are vitamins?

Answer 42

Cofactors that assist enzymic reactions

Question 43

What is the vitamin found in Acetyl CoA?

Answer 43

Pantothenic Acid

Question 44

What feature is **common** to both **Cysteine** and **Acetyl-CoA**?

Answer 44

A Sulphur element

Question 45

In broad terms, what are the **metabolic precursors** of Acetyl-CoA?

Answer 45

Carbohydrates Lipids Proteins

Question 46

When pyruvate is converted to Acetyl-CoA, what other molecule is released?

Answer 46

CO₂

Question 47

Many fuels can be converted to **Acetyl-CoA**, which particular **fuel pathways** are **bidirectional** reactions?

Answer 47

Fatty acids from tryglycerides Ketone Bodies

Question 48

What is the function of lactate dehydrogenase?

Answer 48

Conversion of Lactate to Pyruvate

Question 49

Transamination of pyruvate forms what molecule?

Answer 49

Alanine

Question 50

**Pyruvate** can form what **substance in the TCA cycle** for the purpose of **gluconeogenesis**?

Answer 50

Oxaloacetate

Question 51

What are the two potential pathways when pyruvate is metabolised by the body?

Answer 51

Acetyl CoA Oxaloacetate

Question 52

What types of molecules determine if pyruvate is converted to acetyl CoA or to Oxaloacetate?

Answer 52

Enzymes

Question 53

What effect does high levels of ATP have on the TCA cycle?

Answer 53

Inhibition

Question 54

What are the end products of glycolysis?

Answer 54

Pyruvate NADH

Question 55

Is the **Lactate ⇔ Pyruvate** reaction **reversible** or **irreversible**?

Answer 55

Reversible

Question 56

During low glucose conditions, what is the primary source of energy for the TCA cycle?

Answer 56

Acetyl CoA from Lipose