26.8 Biochem: Nutritional value of FATs and PRO

Question 1

What is protein in the diet used to form?

Answer 1

Structural components (e.g. collagen) and enzymes for metabolism

Question 2

What is the most complex digestive process (CHO/FAT/PRO)?

Answer 2

Protein:

Denature–> AAs–>transport

Question 3

What are the branched chain amino acids? What do they do?

Answer 3

Valine, leucine, isoleucine

Transaminate in muscles (no proven sports enhancement)

Question 4

How much protein do we make and breakdown daily?

How much of this is recycled?

Answer 4

Over 300g (2/3rds of AAs recycled)

Question 5

What do we do to AA to make fuel? What other non-protein products can they make?

Answer 5

Broken down AAs get stripped of carbon for fuel

NTMs

Question 6

What is the byproduct of excess nitrogen removal? What can also be passed directly from the kidneys?

Answer 6

Urea

or ammonia which can be passed directly from kidneys

Question 7

Are proteins stored? What happens in fasting?

Answer 7

Not stored

In fasting, breakdown fuels formation of glucose/ketone bodies

Question 8

What does metabolic oxidation of fats yield in kJ? How about CHO/PRO?

Answer 8

Fats: 37kJ/g

PRO/CHO: 17kJ/g

Question 9

How many MJ of body fat and glycogen does an ‘average human’ store? How long can this fuel last?

Answer 9

400MJ body fat (40 day fast)

6.5MJ glycogen (overnight)

Question 10

Can the brain use fats for energy?

Answer 10

No, ketone bodies derived from fatty acids instead

Question 11

What are free fatty acids used for? What kind of action do they have? Are they basic or acidic?

Answer 11

For metabolic fuel, detergents and dangerously acidic

Question 12

What is TAG? Why do we store it?

Answer 12

Triacylglycerol is a neutral lipid for storage

Question 13

What are the steps for dietary fat to storage?

Answer 13

Dietary fat–> free fatty acids–> chylomicrons–> storage/use

Question 14

Where do chylomicrons travel?

Answer 14

In lymph (cloudy post meal)
Up thoracic duct
Into R/L subclavian veins and into thorax -enter general circulation (bypassing the liver)

Question 15

What are fatty acids carried by? Why can this contribute to a heart attack?

Answer 15

Serum albumin

If fatty acid exceeds carrying capacity, a heart attack following physical stress may occur

Question 16

What are fat mobilising hormones? What is a second messenger?

Answer 16

Adrenaline and glucagon (cAMP 2nd messenger)

Glycerol also exported

Question 17

What transports fatty acl-CoA for oxidation? Where?

What is the rate limiting step for B-oxidation?

Answer 17

Carnitine into mitochondria

Carnitine dependent transport, rate limiting step

Question 18

Where does Acetyl-CoA come from?

Answer 18

Fatty acid–>acetyl-CoA

Question 19

When are ketone bodies made? Where?

What are they?

Answer 19

During starvation (glucose and FFAs stay stable) made by liver for fuel

A mix of acetoacetate, B-hydroxybutyrate and acetone

Question 20

What is a determiner of protein amount?

Answer 20

Nitrogen balance

Question 21

What is the PRO consumption of a typical Australian? How much nitrogen is this?

Answer 21

100g/day, 16g of nitrogen

15g N as urea in urine

Question 22

What is corn deficient in? What can this cause? What are the symptoms?

Answer 22

Tryptophan

Can cause pellagra

4 Ds (photosensitive dermatitis, diarrhea, dementure, death)

Question 23

What is a Mailard reaction? What temp does it occur?

Answer 23

Bread into brown toast, breaking down long chains (lysine)

150-300 degrees C

Question 24

What produces alanine? Why?

Answer 24

Muscle, carries excess nitrogen to liver/kidneys

-Alanine cycle

Question 25

What occurs in gout? Why?

Answer 25

Uric acid, needle crystals build up in joints (and immune system is activated)

Question 26

What do tryptophan supplements do?

Answer 26

Actually can kill you... avoid amino acid supplements