Glycolysis

Question 1

the fed state under the influence of

Answer 1

Insulin

Question 2

Phase of energy evolution

Answer 2

-In the second phase, five subsequent reactions
convert these two molecules of glyceraldehyde-3-phosphate into two molecules of pyruvate

Question 3

Products of Glycolysis

Answer 3

ATP
NADH
Pyruvate/Lactate

Question 4

Fate of Glucose-6-P

Answer 4

❑ Glycolysis
❑ Pentose phosphate pathway,
❑Uronic acid pathway
❑ Glycogenesis.

Question 5

Hexokinase

Answer 5

Low Km

Question 6

Hexokinase inhibited by

Answer 6

G6P

Question 7

Hexokinase deficiency causes

Answer 7

Hemolytic anemia

Question 8

Hexokinase maintains

Answer 8

Intracellular glucose concentration

Question 9

Gluokinase distribution

Answer 9

Liver and Beta cells of pancreas

Question 10

Gluokinase

Answer 10

High Km

Question 11

Is Glucokinase inducible?

Answer 11

Yes, amount present in liver is controlled by insulin

Question 12

Patients with DM show less activity of

Answer 12

Glucokinase

Question 13

Significance of glucokinase

Answer 13

Involved in maintaining blood glucose concentration

Question 14

Rate limiting step in glycolysis

Answer 14

PFK-1

Question 15

Pyruvate kinase deficinecy leads to

Answer 15

Hemolytic aneima

Question 16

Anaerobic glycolysis conditions

Answer 16

Glycolysis proceeds in the absence of oxygen (anaerobically)
* When cells have a limited supply of oxygen (renal medulla),
* Under conditions of hypoxia
* In cells lacking mitochondria (RBCs)
* In conditions of greater demands for ATP such as skeletal muscle during
high-intensity exercise

Question 17

The Metabolic Fates of Pyruvate under aerobic conditions

Answer 17

Pyruvate can be sent (through formation
of Acetyl Co A) into the citric acid cycle,
where it is oxidized to CO2 with the
production of additional NADH and
FADH2

Question 18

The Metabolic Fates of Pyruvate under anerobic
condition

Answer 18

Pyruvate is reduced by the NADH to
lactate, catalyzed by lactate
dehydrogenase

Question 19

Coupling reactions

Answer 19

Reoxidation of NADH via lactate formation allows glycolysis to proceed in the absence of O2 by regenerating sufficient NAD+ used for glyceraldehyde 3 phosphate dehydrogenase

Question 20

Tissues that function under hypoxic conditions

Answer 20

produce Lactate

Question 21

tissues that normally derive much of
their energy from glycolysis and produce
lactate include

Answer 21

brain, gastrointestinal tract,
renal medulla, retina, and skin

Question 22

Significance of RL Shunt

Answer 22

• It does serve to provide 2,3
  -bisphosphoglycerate,
  which binds to hemoglobin, decreasing its affinity
  for oxygen, and so making oxygen more readily
  available to tissues.
• 2,3-BPG can help to prevent tissue hypoxia in
  conditions where it is most likely to occur.
• Fetal hemoglobin (HbF) exhibits a low affinity for
  2,3-BPG, resulting in a higher binding affinity for
  oxygen.
• That’s the way O2 flows from the mother to the
  fetus.

Question 23

Characteristics of pyruvate kinase deficiency

Answer 23

Inheritance autosomal recessive
* Chronic anemia
* Absence of Heinz bodies (Heinz bodies are more characteristic of glucose-6-P
dehydrogenase deficiency)
* Increase 2, 3 BPG concentration, thus lesser than normal oxygen affinity.
* Normal exercise tolerance

Question 24

Causes of lactic acidosis

Answer 24

Circulatory insufficiency (shock, cardiac failure),
* Severe anemia, mitochondrial enzyme defects, and
* Inhibitors (carbon monoxide, cyanide)
* Alcohol intoxication
* Pyruvate dehydrogenase complex deficiency,
* Severe muscular exercise,
* Von Gierke’s disease

Question 25

Fluoride acts primarily by inhibiting

Answer 25

enolase in the glycolytic pathway, which catalyzes the
conversion of 2, phosphoglycerate to Phosphoenol pyruvate.

Question 26

Arsenate toxicity

Answer 26

All enzymes containing -SH groups are affected by Arsenic poisoning.
* Arsenate (pentavalent form of Arsenic) can interfere with glycolysis at the step of Glyceraldeyde-3-P dehydrogenase thereby causing decreased ATP and NADH production by glycolysis, without inhibiting the pathway itself.

Question 27

Inhibitor of Lactate dehydrogenase

Answer 27

Oxamate

Question 28

Due to a high Km for glucose, glucokinase becomes important metabolically only when?

Answer 28

liver glucose levels are high.

Question 29

High ATP concentrations

Answer 29

“turns off” glycolysis

Question 30

Role of ATP

Answer 30

allosteric inhibitor

Question 31

Phosphofructokinase is inhibited by

Answer 31

Citrate

Question 32

Role of Fr 2,6 bisphosphate

Answer 32

allosteric activator

Question 33

What enzyme stimulates PFK1 and inhibits F1,6 Bisphosphatase

Answer 33

Fructose-2,6-bisphosphate

Question 34

High insulin/glucagon decrease

Answer 34

cAMP and reduces levels of PKA

Question 35

Elevated F2,6 bisphosphate activates

Answer 35

PFK-1 which leads to increased rate of glycolysis

Question 36

Pyruvate Kinase activated by

Answer 36

AMP and fructose-1,6-bisphosphate

Question 37

pyruvate kinase inhibited by

Answer 37

ATP, acetylCoA, and alanine.

Question 38

Under conditions of hypoxia

Answer 38

the rate of glycolysis increases to maintain ATP
levels.

Question 39

In tumors and other proliferating or developing cells,

Answer 39

the rate of glucose uptake dramatically increases, used for anabolic processes needed to support cell proliferation.