Gluconeogenesis

Question 1

GLUCONEOGENESIS

It is the process by which glucose molecules are produced from _______ precursors.

These include ____,___ amino acids, _____ part of fat and ______ derived from odd chain fatty acids

Answer 1

non-carbohydrate

lactate; glucogenic; glycerol

propionyl CoA

Question 2

Gluconeogenesis occurs mainly in the _____, and to a lesser extent in the ______.

The pathway is partly _____ and partly _______.

Answer 2

liver

renal cortex

mitochondrial

cytoplasmic

Question 3

Key Gluconeogenic Enzymes

1. __________
2. ___________
3. ____________
4. ________________

Answer 3

Pyruvate carboxylase

Phosphoenol pyruvate carboxy kinase

Fructose-1-6-bisphosphatase

Glucose-6-phosphatase

Question 4

Gluconeogenesis is m a reversal of glycolysis.

Answer 4

F

Gluconeogenesis involves several enzymes of glycolysis, but it is not a reversal of glycolysis.

Question 5

Pyruvate Carboxylase Reaction

Pyruvate in the _____ enters the _____.

Then, ________ of pyruvate to ______ is catalysed by a mitochondrial enzyme, pyruvate carboxylase . It needs the co-enzymes _____ and ____

Answer 5

cytoplasm

mitochondria

carboxylation; oxaloacetate

biotin and ATP.

Question 6

Gluconeogenesis

The carboxylation of pyruvate takes place in mitochondria.
So, oxaloacetate is generated inside the mitochondria.

This oxaloacetate has to be transported from mitochondria to ______, because further reactions of gluconeogenesis are taking place in _____.

This is achieved by the ___________________.

Answer 6

cytosol

cytosol

malate aspartate shuttle

Question 7

In malate aspartate shuttle

Oxaloacetate is first converted to ____, which traverses the membrane and reaches ____ where it is then re-converted to oxaloacetate.

Oxaloacetate may also be transported as aspartate formed by _____ of oxaloacetate.

Answer 7

malate ; cytoplasm

transamination

Question 8

Malate dehydrogenase is present in both mitochondria and cytoplasm.

T/F

Answer 8

T

Question 9

When alanine is the substrate for gluconeogenesis, the ____ shuttle predominantly operates, because ____ is also required in the cytoplasm for the gluconeogenesis to continue.

When lactate is the substrate for gluconeogenesis, the _____ shuttle operates, because sufficient _____ is available in the cytoplasm by the LDH reaction.

Answer 9

malate

NADH

aspartate

NADH

Question 10

Phosphoenol Pyruvate Carboxy Kinase

In the cytoplasm, PEPCK enzyme then converts _______ to ______ by removing a molecule of ___.

____ donates the phosphate

Answer 10

oxaloacetate to phosphoenol pyruvate

CO2

GTP

Question 11

Partial Reversal of Glycolysis

The phosphoenol pyruvate undergoes further reactions catalyzed by the glycolytic enzymes to form ______

Answer 11

fructose-1,6-bisphosphate

Question 12

In gluconeogenesis

Fructose 1,6-bis-phosphate is then acted upon by _______ to form __________

Answer 12

fructose 1,6-bisphosphatase

fructose -6-phosphate.

Question 13

Gluconeogenesis

The glucose 6-phosphate is hydrolysed to _______ by _________

Answer 13

free glucose

glucose-6-phosphatase.

Question 14

Glucose-6-phosphatase is active in ______.

It is present in _____ and ______ to a lesser extent, but is absent in _____.

Answer 14

liver

kidney and intestinal mucosa

muscle

Question 15

Energy Requirement of glyuconeogenesis

The reactions catalyzed by pyruvate carboxylase, phosphoenol pyruvate carboxy kinase and phospho glycerate kinase require ___ ATP each

so ___ ATPs are used by 1 pyruvate residue to produce ___ molecule of glucose; or ___ ATPs are required to generate ___ glucose molecule.

Answer 15

one

3

one-half

6

one

Question 16

Lactate to glucose

The lactate formed in the muscle is transported to the _____ where _______ converts lactate to _______. The pyruvate enters the gluconeogenic pathway to form ____.

Answer 16

liver

lactate dehydrogenase

pyruvate

glucose

Question 17

____________ Cycle aka Cahill Cycle

Answer 17

Glucose-Alanine

Question 18

Glucose-Alanine Cycle (Cahill Cycle)

Alanine is transported to ____ where it is _____ to _____ and converted to glucose.

Answer 18

liver

transaminated

pyruvate

Question 19

Glucose-alanine cycle is important in conditions of starvation

T/F

Answer 19

T

Question 20

Alanine cycle is intimately related with ____ cycle

Answer 20

Cori’s

Question 21

Propionyl CoA is formed from odd chain fatty acids and carbon skeleton of some amino acids. It is converted to _______.

It is a (minor or major?) source for glucose.

Answer 21

succinyl CoA

Minor

Question 22

Even chain fatty acids can be converted to glucose

T/F

Answer 22

F

Even chain fatty acids cannot be converted to glucose

Question 23

_______ is an activator of pyruvate carboxylase

_____ is an activator of Fructose-1,6-bisphosphatase

Answer 23

Acetyl CoA

Citrate

Question 24

Gluconeogenesis is (enhanced or hindered ?) by ATP.

Answer 24

Enhanced

Question 25

CORI'S CYCLE OR LACTIC ACID CYCLE It is a process in which glucose is converted to lactate in the ____; and in the ____ this lactate is re-converted into glucose.

Answer 25

muscle liver

Question 26

In an actively contracting muscle, pyruvate is reduced to ______ which may tend to ____ in the muscle.

Answer 26

lactic acid accumulate

Question 27

The muscle cramps, often associated with strenuous muscular exercise, are thought to be due to ________

Answer 27

lactate accumulation

Question 28

To prevent the lactate accumulation, body utilises Cori's cycle. This lactic acid from muscle diffuses into the ______. Lactate then reaches ____, where it is ____ to ____. Thus, it is channelled to ______ pathway .

Answer 28

blood liver oxidized pyruvate gluconeogenesis

Question 29

______ is the storage form of carbohydrates in the human body. The major sites of storage are _____ and _____.

Answer 29

Glycogen liver and muscle

Question 30

The glycogen content of liver is (more or less?) than in the skeletal muscle But the total quantity of muscle glycogen is (more or less?) than liver glycogen because of the ________

Answer 30

More Less larger muscle mass

Question 31

When blood glucose level falls, (muscle or liver ?) glycogen is broken down and helps to maintain blood glucose level.

Answer 31

Liver

Question 32

The function of muscle glycogen is to act as ______ for ______.

Answer 32

reserve fuel muscle contraction

Question 33

All the enzymes related to glycogen metabolism are located in the _______

Answer 33

cytoplasm

Question 34

In glycogenolysis _______ removes glucose as _________ from glycogen (phosphorolysis) The _____ linkages in the glycogen are cleaved. It removes glucose units one at a time. Enzyme sequentially hydrolyses alpha-1,4 glycosidic linkages, till it reaches a glucose residue, ____ glucose units away from a branch point .

Answer 34

Glycogen phosphorylase glucose-1-phosphate alpha-1,4 3-4

Question 35

Glycogen phosphorylase contains __________ as a prosthetic group.

Answer 35

pyridoxal phosphate (PLP)

Question 36

Glycogen phosphorylase | cannot attack the ____ linkage at _____ point.

Answer 36

1,6 branch

Question 37

If glycogen phosphorylase alone acts on a glycogen molecule, the final product is a highly branched molecule; it is called _____

Answer 37

limit dextrin.

Question 38

Regulation of Muscle Glycogen Phosphorylase Skeletal muscle glycogen is degraded only when the demand for ATP is (high or low?) . The regulation of glycogenolysis in skeletal muscle is by ______ and ____ released from sarcoplasmic reticulum. _____ has no effect on muscle glycogenolysis.

Answer 38

High epinephrine and calcium Glucagon

Question 39

Debranching by bifunctional (two) Enzymes Then a block of __ glucose residues ( ____ unit) are transferred from the branching point to another branch. This enzyme is alpha-1,4 → _______. Now the branch point is free. Then __________ (debranching enzyme) can hydrolyse the remaining glucosyl unit held in alpha-1,6 linkage at the branch point This glucose residue is released as free glucose. At this stage, the ratio of glucose-1phosphate to free glucose is about __:__ The _______ and _______ will together convert the branch point to a linear one. With the removal of the branch point, phosphorylase enzyme can proceed with its action.

Answer 39

3; trisaccharide alpha-1,4 glucan transferase alpha1,6- glucosidase 8:1. transferase and alpha-1,6-glucosidase

Question 40

In glycogenolysis Phosphogluco mutase Phosphorylase reaction produces _______ while debranching enzyme releases _____. The glucose-1-phosphate is converted to _________ by ________

Answer 40

glucose-1phosphate glucose glucose-6-phosphate phosphoglucomutase

Question 41

In glycogenolysis Next, hepatic _________ hydrolyses glucose-6-phosphate to glucose. The free glucose is released to the ______

Answer 41

glucose-6-phosphatase blood stream.

Question 42

——— Lacks Glucose-6-phosphatase

Answer 42

Muscle

Question 43

Muscle will release glucose to the blood stream T/F With reason

Answer 43

F Muscle will not release glucose to the blood stream, because muscle tissue does not contain glucose-6-phosphatase.

Question 44

Fate of glucose-6-phosphate in muscle

Answer 44

Instead, in muscle, glucose-6-phosphate undergoes glycolysis to produce ATP for muscle contraction.

Question 45

In muscle, the energy yield from one glucose residue derived from glycogen is ____ ATP molecules Why???

Answer 45

3 because no ATP is required for initial phosphorylation of glucose (step 1 of glycolysis).