Bob's 2

Question 1

What are the four stages of catabolism?

Answer 1

Stage 1- GI breakdown to molecules for absorption

Stage 2- some oxidation and breakdown to metabolic intermediates like pyruvate.

Stage 3- Tricarboxylic acid or Krebs cycle where through oxidation reducin power and energy is released

Stage 4- oxidative phosphorylation in the mitochondrion. Reducing power converted to ATP.

Question 2

Where does stage 2 catabolism occur?

Answer 2

Both in the cytoplasm and mitochondria.

Question 3

Where does stage 3 (krebs orTCA cycle) of catabolism occur?

Answer 3

Matrix of the mitochondria

Question 4

Where des stage 4 f catabolism occur?

Answer 4

Inner matrix of the mitochondria. Oxygen is required for electron transport chain.

Question 5

What is the general structure of carbohydrate?

Answer 5

(CH2O)n

Question 6

What should glucose concentration in the blood be?

Answer 6

5mM

Question 7

What tissues have an absolute requirement for glucose metabolism meaning that it is essential for them?

Answer 7

Red blood cells
Neutrophils
Lens of eye
Innermost cells of kidney medulla

Brain much rather glucose but can use ketone bodies during starvation however it takes time to adapt to their use.

Question 8

What are the three types of lactose intolerance?

Answer 8

Primary lactase deficiency where there’s an absence of lactase persistence allele. Only occurs in adults.

Secondary where small intestine lining is damaged. Gastroenteritis, coeliac disease, crowns disease and ulcerative colitis. Occurs in infants and adults and is generally reversible.

Congenital caused by an autosomal recessive defect in the lactase gene and this is extremely rare.

Question 9

What shoudlblood glucose level be?

Answer 9

3.3-5 mmol/litre

Question 10

How are monosaccharides absorbed?

Answer 10

Glucose and galactose into intestinal epithelium cell through SGLT 1 (sodium glucose transporter 1) through active transport.

From cell into capillary through GLUT 2 which is passive due to higher glucose concentration in epithelial cell.

Question 11

Glucose transporters?

Answer 11

Facilitated diffusion.

Glut 2 is glucose sensing in pancreatic beta cells.

Glut 4 is recruited to the surface of cells in response to insulin.

Question 12

Is glycolysis reversible?

Answer 12

No its irreversible

Question 13

Where does glycolysis occur?

Answer 13

In the cytoplasm of every tissue.

Question 14

What are the three key enzymes in glycolysis?

Answer 14

Hexokinase
Phsphofructkinase
Pyruvate kinase

To convert pyruvate to glucose in gluconeogenesis these steps must be bypassed

Question 15

What des hexokinase do?

Answer 15

Adds a phosphate to glucose and this prevents it from crossing back through the cell membrane.

Question 16

What does phosphofructokinase do?

Answer 16

Reaction is very exothermic and so is irreversible and a committing step.

Question 17

Why do we invest ATP at the beginning of glycolysis?

Answer 17

To prevent glucose from passing back through the cell membrane and to make it more unstable so that it commits to glycolysis.

Question 18

How many ATP are given and how many are made?

Answer 18

Two are given and four are made.

Question 19

Why are there on many steps in glycolysis?

Answer 19

Efficient energy conservation as small energy releases easier to capture.

Chemistry is easier in small steps

Allows for fine control- can divert at various stages if necessary

Gives versatility- can make intermediates and some reactions can be used in reverse.

Question 20

Clinical use of glycolysis?

Answer 20

measure uptake of radioactive deoxyglucose and use to see and measure cancers.