1. Explain why glucose consumption must increase in hypoxic tissues to provide t
ID: 69655 • Letter: 1
Question
1. Explain why glucose consumption must increase in hypoxic tissues to provide the same amount of ATP that could be produced from glucose in normoxic (normal O2 levels) tissues
B) In hypoxic tissues, in contrast to normoxic tissues, ATP is additionally consumed to transform lactate to pyruvate.
C) In hypoxic tissues, ATP is produced only by glycolysis, whereas in normoxic tissues, the citric acid cycle + oxidative phosphorylation can be used.
2. How would increasing LDH expression increase the rate of glycolysis?
A) The LDH reaction ensures a continuous supply of oxidized NAD+ to allow glycolysis to operate at an increased rate.
B) The LDH reaction produces supplementary amounts of reduced NADH to allow glycolysis to operate at an increased rate.
C) The LDH activity increases the ratio NADH/NAD+ to allow glycolysis to operate at an increased rate.
D) The LDH activity increases the level of lactate in tissues to allow glycolysis to operate at an increased rate.
3. How would increasing PDK expression decrease the rate of mitochondrial respiration?
A) PDK activity requires a huge consumption of ATP molecules. ATP are formed easily by glycolysis in hypoxic tissues, so processes of mitochondrial respiration are deprived.
B) PDK phosphorylates the E1 subunit of PDH complex, decreasing flux through citric acid cycle. Thus, NADH production and respiration is decreased.
C) PDK increases the conversion of pyruvate to lactate in the mitochondria, decreasing NADH production. Thus, the rate of mitochondrial respiration is decreased.
A) Oxygen is the limiting reactant in ATP producing, so ATP is produced in hypoxic tissues slowlier than in normoxic tissuesB) In hypoxic tissues, in contrast to normoxic tissues, ATP is additionally consumed to transform lactate to pyruvate.
C) In hypoxic tissues, ATP is produced only by glycolysis, whereas in normoxic tissues, the citric acid cycle + oxidative phosphorylation can be used.
D) In hypoxic tissues, ATP is produced only by glycolysis, whereas in normoxic tissues, the citric acid cycle + oxidative phosphorylation can be used.2. How would increasing LDH expression increase the rate of glycolysis?
A) The LDH reaction ensures a continuous supply of oxidized NAD+ to allow glycolysis to operate at an increased rate.
B) The LDH reaction produces supplementary amounts of reduced NADH to allow glycolysis to operate at an increased rate.
C) The LDH activity increases the ratio NADH/NAD+ to allow glycolysis to operate at an increased rate.
D) The LDH activity increases the level of lactate in tissues to allow glycolysis to operate at an increased rate.
3. How would increasing PDK expression decrease the rate of mitochondrial respiration?
A) PDK activity requires a huge consumption of ATP molecules. ATP are formed easily by glycolysis in hypoxic tissues, so processes of mitochondrial respiration are deprived.
B) PDK phosphorylates the E1 subunit of PDH complex, decreasing flux through citric acid cycle. Thus, NADH production and respiration is decreased.
C) PDK increases the conversion of pyruvate to lactate in the mitochondria, decreasing NADH production. Thus, the rate of mitochondrial respiration is decreased.
Explanation / Answer
1. C and D options are same and correct.
2. A. (LDH enzyme converts NADH to NAD+; This NAD+ is required in 5th reaction of glycolysis where glyceraldehyde3- phosphate is converted to 1,3 bis-phosphoglycerate).
3. B. (Excess PDK will reduce the flux through citric acid cycle, overall reducing mitochondrial respiration)
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