L31 Aerobic Vs Anaerobic Respiration

Question 1

Which cells utilize anaerobic respiration

Answer 1

Occurs in tissues that are poorly perfused either under normal conditions ex: lens and cornea of eye and kidney medulla
or due to pathological reasons as exercising muscles or lack of mitochondria such as RBCs

Question 2

How many NADH mol are produced by aerobic glycolysis

Answer 2

2 by action of glyceraldehyde 3 phosphate dehydrogenase which produce 3 ATP each

Question 3

Net ATP from aerobic glycolysis

Answer 3

8

Question 4

How is acetyl co A made from 2 pyruvate molecules

Answer 4

Irreversible reaction by action of pyruvate dehydrogenase complex

Question 5

What are the 5 co enzymes needed for PDH to function

Answer 5

thymine pyrophaste (TPP)
Lipoic acid
NAD
FAD
Coenzyme A

Question 6

How is PDH regulated

Answer 6

Feedback inhibition by elevated acetyl COA and NADH
Covalent modification(dephosphorylated is active one by action of insulin)
Mercury can inhibit PDH
arsenic poisoning due to inhibition of lipoic acid

Question 7

PDH deficiency

Answer 7

Either from birth—person doesnt survive

Or acquired like deficiency of TPP and NAD due to severe nutritional deficiency or alcohol abuse—lactic acidosis occurs and can affect neurological and mental ability since brain cells are unable to produce sufficient ATP

Question 8

How many ATP molecules are produced from complete glucose oxidation (and categorize them)

Answer 8

Up to 38
8 from glycolysis
6 from 2 NADH produced by PDH enzyme acting on 2 pyruvate
24 ATP from oxidation of 2 acetyl COA in CAC

Question 9

Whats another fate for pyruvate

Answer 9

Under aerobic conditions it made be carboxylated in to oxaloacetate by pyruvate carboxylase
Biotin dependent

Question 10

How many ATP mol are produced from anaerobic Glycolysis

Answer 10

2 ATP

Question 11

Whats the fate of pyruvate in anaerobic respiration

Answer 11

Converted to lactate by LDH

Question 12

Why do cramps occur

Answer 12

Due to excessive production of NADH pyruvate is converted to lactate and it accumulates in and causes a drop in intracellular PH

Question 13

Describe what happens in the cori cycle

Answer 13

Lactic acid enters cori cycle and lactate formed during anaerobic oxidation of glucose diffuses to blood then liver.
In the liver lactate is oxidized to pyruvate and converted to glucose which goes back to tissues and is used for energy production

Question 14

Describe lactic acidosis

Answer 14

Elevated concentrations of lactate in plasma occur when there is a generalized decrease in tissue perfusion
(In hypotension,myocardial infarction and hemorrhage)
Decrease O2 in tissues decreases ATP synthesis and cells rely on anaerobic glycolysis
Symptoms(tiredness,shallow breathing,disorientation)
Could be fast within minutes or may last days

Question 15

How is NADH transported in to mitochondria

Answer 15

Substrate shuttles

Glycerol 3 phosphate shuttle and malate shuttle

Question 16

How does the glycerol 3 phosphate shuttle work

Answer 16

NADH is used to convert dihydroxyacetone phosphate by using glycerol 3 phosphate dehydrogenase

Glycerol 3 phosphate passes through mitochondria where it is converted back in to DHAP but produces FADH2 instead of NADH

Question 17

How does the malate shuttle work

Answer 17

Oxaloacetate uses NADH to be converted to Malate

Malate passed in to mitochondria where it is converted again to oxaloacetate producing NADH