Glucose metabolism

Question 1

Define substrate level phosphorylation

Answer 1

ATP production by direct transfer of high energy phosphate group from an intermediate substrate in biochemical pathway to ADP. -in glycolysis

Question 2

Define oxidative phosphorylation

Answer 2

ATP produced using energy derived from transfer or electrons in electron transport system

Question 3

What are the reactions in alcoholic fermentation

Answer 3

1. Pyruvate–>acetaldehyde (H+–>CO2)
   
   • Pyruvate decarboxylase
2. Acetaldehyde–>ethanol (NADH–>NAD+ + H+)
   - Alcohol dehydrogenase

Question 4

What are the reactions in lactate generation

Answer 4

Pyruvate–>lactate (NADH–>NAD+ + H+)

Lactate dehydrogenase

Question 5

What is an inc. LDH diagnostic of?

Answer 5

• Stroke
• Heart disease
• Liver disease
• Muscle injury
• Muscular dystrophy
• Pulmonary infarction

Question 6

What an increased CP diagnostic of?

Answer 6

• Myocardial infarction
• Determine extent of muscular disease
• Evaluate cause of chest pain
• Help discover carriers of muscular dystrophy

Total- 70%accurate
Isoenzyme - 90% accurate

Question 7

What is the structure of the PDC?

Answer 7

1. Pyruvate decarboxylase + thiamine pyrophosphate (TPP)
2. Lipoamide reductase - transacetylase + lipoamide
3. Dihydrolipoyl dehydrogenase + FAD+
4. CoA
5. NAD+

Question 8

How is acetyl CoA produced?

Answer 8

Pyruvate + HS-CoA + NAD+ –> acetyl CoA + Co2 + NADH

1. Decarboxylation of pyruvate to give hydroxyethyl TPP
2. Oxidation and transfer to lipoamide to give acetylipoamide - generation of acetyl group
3. Transfer of acetyl group to CoA to give acetyl CoA
4. Regeneration of oxidised lipoamide
5. Regeneration of oxidised FAD to generate NADH

Question 9

What is produced by the TCA?

Answer 9

3x NADH
1x GTP
1x FADH2
2x CO2
12xATP

Question 10

Where are TCA enzymes found?

Answer 10

• All soluble proteins in matrix
• Except succinate dehydrogenase (integral membrane protein firmly attached to inner membrane) - passes electrons directly from FADH2to co-enzymeQ

Question 11

Define transamination

Answer 11

amine group transferred from AA to keto acid forming new pairs of acids (one keto and one amino)

Question 12

Give a reaction of transamination

Answer 12

Alanine + alpha ketoglutarate–>pyruvate + glutamate

- Alanine aminotransferase

Question 13

What is the difference between NAD and NADP?

Answer 13

NADPH takes part in anabolic reactions, NADH in catabolic

Question 14

How are coenzymes re-oxidised?

Answer 14

NADH + H+ + 1/2 O2 –>NAD+ + H2O

FADH2 + 1/2O2 –> FAD + H2O

Question 15

What are the structure of electron transport chain?

Answer 15

3 membrane complexes:

1. NADH dehydrogenase
2. Cytochrome b-c1 
3. Cytochrome oxidase 

2 mobile carriers:

1. Coenzyme Q
    2. Cytochrome C

Question 16

What is a redox couple?

Answer 16

substrate that can exist in oxidized and reduced state eg- NAD+/NADH

Question 17

Explain the chemiosmotic model:

Answer 17

1. Movement of proton from matrix to intermembrane space controlled by ETC
2. Pumped proton allowed back in via channel coupled with ATP synthase

Question 18

What is the structure of ATPase?

Answer 18

Multimeric enzyme consisting of:
Fo subunit: a, b, c - membrane bound
F1: alpha, beta, gamma - part projecting into matrix

Question 19

How is ATP synthesized?

Answer 19

1. When H+ flow through F0, rotation of F1 drives transition states and alters ATP and ADP affinity
2. Conformational energy flows from catalytic subunit into bound ADP and Pi promotes ATP formation

• F1 may a also works in reverse to hydrolyze ATP and pump out protons depending on proton flow direction

Question 20

What is the role of succinate dehydrogenase in oxidative phosphorylation

Answer 20

integral membrane protein that is firmly attached to the inner surface of the inner mitochondrial membrane , communicate directly with ubiquinone.

Question 21

Where is the malate aspartate shuttle found?

Answer 21

liver and heart