integration of metabolism

Question 1

What can the brain metabolise?

Answer 1

Glucose and ketone bodies
b-hydroxybutyrate
acetoacetate

Question 2

Excess G6P is converted into

Answer 2

Glycogen or pentose phosphates which are converted into nucleotides

Question 3

Pyruvate can be converted into

Answer 3

Lactate or amino acids

Question 4

Acetyl coA can be converted into

Answer 4

Ketone bodies or Cholesterol and lipids

Question 5

Products from TCA can make

Answer 5

Amino acids

Question 6

Nucleotides can be made from

Answer 6

Amino acids and pentose phosphates

Question 7

Describe Gluconeogenesis?

Answer 7

Pyruvate to oxaloacetate (pyruvate carboxylase) Oxaloacetate to phosphoenolpyruvate (PEP carboxylase) To fructose 1,6 bisphosphate (lose 6 ATPs) To F6P (F16bP phosphotase) To G6P To glucose (G6 phosphotase)

Question 8

How many ATP is produced/made in glycolysis and gluconeogenesis

Answer 8

Glycolysis: +2ATP
gluconeogenesis: -6ATP

Question 9

Amino acids can enter respiration

Answer 9

As pyruvate Acetyl coA

In TCA

Question 10

What is the effect of adrenalin

Answer 10

-causes an increase in muscle glycolysis
-increases gluconeogenesis
increases the release of fatty acids

Question 11

state the difference in the hexokinase used in the muscle compared to the liver

Answer 11

Hexokinase 1:
in muscles, has high affinity for glucose
rapidly increases as glucose concentration increases, and reaches maximum at low glucose conc.
highly sensitive to G6P inhibition.

Hexokinase 4:
low glucose affinity
reaction is much slower in liver than muscle at same glucose conc.
less sensitive to G6P, so G6P can accumulate and Hk 4 will continue to convert glucose to G6P.

Question 12

What can gluconeogenesis use and what happens?

Answer 12

Amino acids
glycerol
lactate
-is not a direct reversal of glycolysis, since different enzymes are needed to bypass the irreversible reactions of glycolysis
-requires an investment of ATP
is essentially only a function of liver

Question 13

What is free gibbs energy for glycolysis and gluconeogenesis

Answer 13

Glycolysis: +90
gluconeogenesis:-38

Question 14

Which of the following processes are stimulated by the pancreatic hormone glucagon (pictured)?

Answer 14

glycogenolysis

gluconeogenesis

Question 15

Directly after eating a meal, blood glucose levels initially rise. How is this controlled?

Answer 15

• increased insulin secretion from pancreatic islets

- increased triglyceride synthesis in adipose tissue

Question 16

Following a meal blood glucose levels start to fall. How is this controlled?

Answer 16

• increased glucose production in liver by gluconeogenesis
• increased glucose production in liver by glycogenolysis
• utilisation of fatty acid breakdown as an alternative substrate for ATP production

Question 17

In times of prolonged fasting what happens

Answer 17

-protein breakdown provides amino acids for gluconeogenesis
-ketone bodies are produced from fatty acids and amino acids as a partial glucose
substitute for brain
-TCA cycle intermediates are reduced to provide substrates for gluconeogenesis

Question 18

What releases glucocorticoids?

Answer 18

The adrenal cortex