80 - Nutritional Value of Fats and Proteins

Question 1

Why can’t fat be converted to glucose?

Answer 1

Can’t convert Acetyl-CoA to pyruvate

Question 2

Energy reserves of a normal 70kg male

Answer 2

400MJ of fat.
100MJ in protein
6.5MJ of glycogen

Question 3

Primary fat made by humans

Answer 3

Palmitic acid (saturated)
Some unsaturated fats (mostly from plants)

Question 4

Why do free fatty acids need to be packaged into TAGs?

Answer 4

Detergents, acidic

Question 5

Protein with which free fatty acids are packaged to form chylomicrons

Answer 5

ApoC-II

Question 6

How do chylomicrons get into the blood?

Answer 6

Travel through lymphatics into the blood (through thoracic duct)

Question 7

Appearance of lymph after a fatty meal

Answer 7

Cloudy

Question 8

Blood vessels into which thoracic duct empties into

Answer 8

Left and right subclavian veins

Question 9

How is fat mobilised for energy?
1
2
3
4

Answer 9

1) Adrenaline and glucagon released, both stimulate cAMP as a secondary messenger.
2) Fatty acids are carried by serum albumins.
3) Glycerol is used for glucose synthesis
4) Rarely (EG with serious exercise) amount of fatty acid released overwhelms albumin, which might contribute to a heart attack with sustained physical stress

Question 10

What transports acyl-CoA into mitochondria for oxidation?

Answer 10

Carnitine

Question 11

Role of carnitine

Answer 11

Transports acyl-CoA into mitochondria for beta oxidation

Question 12

Amount of ATP generated per molecule of palmitate

Answer 12

106 (from beta oxidation of acetyl CoA)

Question 13

What generates ketone bodies?

Answer 13

Liver mitochondria, from acetyl-CoA

Question 14

What are ketone bodies?

Answer 14

Mixture of acetoacetate, beta-hydroxybutyrate, acetone (acetoacetate and beta-hydroxybutyrate predominate).

Question 15

How can ketones lead to acidosis?

Answer 15

Ketones are strong organic acids.

Question 16

Once glucose is exhausted, first macromolecule used to generate energy

Answer 16

Amino acids from protein

Question 17

Why can’t the brain use FFAs, but can use ketone bodies?

Answer 17

FFAs are long-chain fatty acids, and can’t cross the blood brain barrier.
Ketone bodies are short-chain fatty acids, and can cross the BBB.

Question 18

Use of 100g of protein in the body

1-5

Answer 18

Calculated by looking at nitrogen.
1g of N in faeces
15g of N in urine as urea
Neurotransmitters, haem synthesised
~300g of protein made and broken down each day

Question 19

Disease caused by eating only corn

Answer 19

Pellagra

Question 20

Pellagra

Answer 20

Niacin, tryptophan deficiency from eating only corn.
Clinically manifests as four D’s:
Photosensitive dermatitis, diarrhoea, dementia, death

Question 21

Amino acid deficiency in people who only eat corn

Answer 21

Tryptophan

Question 22

Role of pyradoxyl phosphate

Answer 22

Essential for transamination (link between amino acids and keto acids)

Question 23

Role of alanine in muscle

Answer 23

Produced by muscle to carry excess nitrogen to the liver or kidneys

Question 24

Where is urea produced?

Answer 24

In the liver (from NH4+)

Question 25

Amount of uric acid and urea excreted by a healthy human each day

Answer 25

0.6g of uric acid

30g of urea

Question 26

Disease from not excreting urea

Answer 26

Gout

Question 27

Gout treatment

Answer 27

Allopurinol.