Chap 13; Metabolism Of Carbohydrates

Question 1

Difference between substrate level and oxidative phosphorylation?

Answer 1

In simple words:

• Substrate-Level Phosphorylation: ATP is made directly during specific steps of glycolysis and the citric acid cycle. It happens in the cytoplasm and mitochondria.
• Oxidative Phosphorylation: ATP is made indirectly in the mitochondria by using energy from electrons passed through the electron transport chain, creating a proton gradient that powers ATP synthesis.

• Direct vs. Indirect: Substrate-level is direct ATP production, while oxidative relies on an electron transport chain.
• Location: Substrate-level happens in the cytoplasm and mitochondria; oxidative happens only in mitochondria.
• Amount of ATP: Oxidative phosphorylation produces much more ATP than substrate-level phosphorylation.

Question 2

1. _____ is also called EMP pathway?
2. Glycolysis is pathway for atp synthesis in tissues lacking mitochondria such as?
3. Which enzyme of hexokinase or gluconkinase glycolysis is present in all tissues?

Answer 2

1. Glycolysis
2. Cornea, lens, erythrocytes
3. Hexokinase in all tissues
   Glucokinase in liver

Question 3

1. Compare Km value of glucokinase and hexokinase?
2. What is the regulatory step of glycolysis? Which enzyme?
3. Enzyme glyceraldehyde-3- phosphate is inhibited by?
4. Which rare kinase reaction is reversible?

Answer 3

1. Glucokinase has high km (10 mM) so low affinity ( only for glucose

Hexokinase has low km (0.1mM) so high affinity ( for all hexoses, fructose mannose etc)

2. Fructose 6 phosphate to fructose 1,6 bisphosphate by phosphofructokinase (PFK)
3. Idoacetate and arsenate
4. Phosphoglycerate kinase
   (Converts 1,3- bisphosphoglycerate into 3 phosphoglycerate)

Question 4

1.Which ions are required by enolase of glycolysis?

2. Enolase is inhibited by?

Answer 4

1. Mg 2+ & Mn 2+
2. Fluoride
   (Unusual Competitive inhibitor)

Question 5

For blood glucose estimation, which compound is added and why?

Answer 5

fluoride to prevent glycolysis

Question 6

For blood glucose estimation, which compound is added and why?

Answer 6

fluoride to prevent glycolysis

Question 7

Pyruvate is converted to lactate by?
In presence of which enzyme? Its competitive inhibitor?
In which condition?

Answer 7

Reduced by NADH

Enzyme lactate dehydrogenase
(Competitive inhibitor-oxamate)

Anaerobic

Question 8

Glycolysis in erythrocytes leads to ______ production?

Normal plasma lactic acid?

Oxygen debt can be measured by measurement of what in plasma?

Answer 8

Lactate production since mitochondria is absent for aerobic

2. 4-15 mg/dl
3. Lactic acid

Question 9

What is acidosis? It’s types?

Answer 9

Acidosis is a condition in which the body’s fluids contain too much acid, resulting in a lower than normal pH in the blood and tissues. It can be caused by an increase in acid production, a decrease in acid excretion, or a loss of bicarbonate, which is a base that helps neutralize acids. Acidosis can be classified into two main types:

1. Metabolic Acidosis: Caused by an excess of acid or a loss of bicarbonate in the body. Examples include diabetic ketoacidosis, lactic acidosis, and kidney disease.
2. Respiratory Acidosis: Caused by the accumulation of carbon dioxide in the blood due to impaired lung function, such as in chronic obstructive pulmonary disease (COPD) or severe asthma.

Symptoms of acidosis can include rapid breathing, confusion, fatigue, headache, and in severe cases, it can lead to shock or death if not treated promptly.

Question 10

How many atp produced in aerobic and anaerobic glycolysis for glucose and glycogen?

Answer 10

Glucose*
Anaerobic—2 ATPs
Aerobic—–7 ATPs

Glycogen*
Anaerobic—3 ATPs
Aerobic—–8 ATPs