carbohydrate metabolism

Question 1

glycogen to glucose

Answer 1

glycogenisis

Question 2

glucose to glycogen

Answer 2

glycogenolysis

Question 3

glucose to pyruvate

Answer 3

glycolysis

Question 4

pyruvate to pyruvate

Answer 4

gluconeogenesis

Question 5

two enzymes which convert glucose to glucose 6 phosphate

Answer 5

glucokinase and hexokinase

Question 6

glucokinase has a low affinity for glucose but high capacity and induces insulin and when glucose levels are high stores excessive glucose in the liver. where is it found

Answer 6

liver and pancreatic beta cells

Question 7

hexokinase is found in most tissues and when glucose levels are low is sequesters glucose in the tissues and it has a high affinity fro glucose but low capacity what is the effect on glucose 6 phsotpahe

Answer 7

inhibits

Question 8

glycolysis coverts glucose to pyruvate what type of process is this

Answer 8

anaerobic process

the rate-determining enzyme is phosphofructosekinase-1

Question 9

gluconeogeneiss converts non-carb substrates like pyruvate or lactate to glucose where does it occur

Answer 9

mainly liver , kidney and intestinal epithelium

the rate-determining enzyme is fructose-1,6-biphosphatase
many of the steps are the reverse of the steps found in glycolysis. However, there are 4 ‘non-reversible’ enzymes that are key to gluconeogenesis. It is important to learn these for the exam:

Question 10

what are the 4 non-reversible enzymes key to gluconeogensis

Answer 10

pathway produces fresh glucose

Pyruvate carboxylase
PEP carboyxlase
Fructose-1,6-biphosphatase
Glucose-6-phosphatase

Question 11

pyruvate carboxylase converts pyruvate to oxaloacetate where

Answer 11

mitochondria

Question 12

PEP carboyxlase and Fructose-1,6-biphosphatase work in the cytosol and convert Oxaloacetate → phosphoenolpyruvate and Fructose-1,6-biphosphate → fructose-6-phosphate respectively

glucose 6 phosphatase makes glucose but where does this work

Answer 12

ER

Deficient in von Gierke’s disease

Not present in muscle (why muscles cannot generate glucose)

Question 13

why can’t muscles generate glucose

Answer 13

because they don’t have the enzyme

glucose 6 phosphatase

Question 14

glycogneolysis coverts glycogen to glucose 1 phosphate what is the key enzyme

Answer 14

the key enzyme is glycogen phosphorylase. Following the action of glycogen phosphorylase α-1,6-glucosidase removes the final glucose residue of the branch as a molecule of glucose