The Nutritional Value of Fats and Proteins

Question 1

What is the body’s premium reserve fuel?

Answer 1

Fats

Question 2

What are the functions of protein?

Answer 2

structural dietary component and energy source

Question 3

What is the key structural material of the diet?

Answer 3

protein

Question 4

Protein is used to form

Answer 4

all structural components (eg collagen) and enzymes for metabolism

Question 5

What are the general steps of protein digestion?

Answer 5

denaturing of dietary protein, rendering it to amino acids, transport them via multiple gut transporters

Question 6

What are the implications of branched chain amino acids on performance?

Answer 6

eg valine, leucine, and isoleucine - transaminate in muscles but have no proven role as performance-enhancing

Question 7

How much protein is made and broken down by the body per day?

Answer 7

300g

Question 8

How much of our amino acids are recycled under normal conditions?

Answer 8

2/3rds

Question 9

Broken down amino acids are used for

Answer 9

carbon sources for fuel

Question 10

Amino acids make non-protein products such as

Answer 10

neurotransmitters

Question 11

What is the major waste product to remove excess nitrogen?

Answer 11

urea (some ammonia can be passed direct from kidneys)

Question 12

Breakdown of proteins in fasting fuels

Answer 12

formation of glucose and ketone bodies to maintain brain and RBCs

Question 13

Acetyl-coA is never metabolised to

Answer 13

pyruvate; ie C from fat never becomes C in glucose

Question 14

Fatty acids are metabolised to and from

Answer 14

Acetyl-coA

Question 15

Why can’t the brain use fats for energy?

Answer 15

long-chain fatty acids cannot cross the BBB

Question 16

Fat cells produce what hormones?

Answer 16

leptin and adiponectin to tell the brain how much fat is stored

Question 17

Hormone sensitive lipase

Answer 17

triacylglycerol lipase: converts TAGs to FFAs and glycerol

Question 18

What is the role of carnitine?

Answer 18

Carries fatty acids from fatty acyl-coA across the mitochondrial membrane into the matrix - this is a rate limiting step of beta oxidation

Question 19

What is the role of malonyl-coA?

Answer 19

it is a precursor of fat synthesis and inhibits high energy and blocks the carnitine acytltransferase from transferring fatty acyl-coA into the mitochondrial matrix for beta oxidation (ie fat is being made so don’t break it down)

Question 20

Fats are made in the

Answer 20

cytosol

Question 21

Fats are broken down in

Answer 21

mitochondria

Question 22

Beta oxidation of palmitate produces what yield of ATP via acetyl-coA in Krebs?

Answer 22

106 ATP/palmitate

Question 23

What is the role of citrate?

Answer 23

exits from mitochondria into cytosol to generate acetyl-coA

Question 24

Palmitate is synthesized by

Answer 24

polymerization of acetyl-coA (formed by citrate) by fatty acid synthase

Question 25

Ketone bodies are made by

Answer 25

liver mitochondria to fuel other organs in starvation

Question 26

Ketone bodies are a mixture of

Answer 26

acetoacetate, B-hydroxybutyrate, and acetone (breath only)

Question 27

Ketone body production follows the same pathway as

Answer 27

cholesterol synthesis up to HMG-CoA, but cholesterol is only made in cytosol by HMG-CoA reductase

Question 28

Cholesterol is only made in

Answer 28

cytosol

Question 29

NADH generated in beta oxidation is used

Answer 29

to generate B-hydroxybutyrate from acetoacetate for energy

Question 30

Ketoacidosis

Answer 30

metabolic acidosis due to high concentrations of ketone bodies as a result of failure to produce insulin - unregulated levels of ketone bodies and blood glucose

Question 31

Ketosis

Answer 31

metabolic state where energy supply is ketone bodies (eg starvation) and insulin and blood glucose are low

Question 32

What happens when glycogen stores are depleted (eg starvation)?

Answer 32

protein is broken down to amino acids for gluconeogenesis; after 3-4 days more and more ketone bodies are produced; glucose is maintained by gluconeogenesis from proteins and glycerol from TAG metabolism to FFAs

Question 33

Omega fatty acids in fish oils are

Answer 33

eicosapentaenoic (6) acid and docosahexaenoic (3) acid (essential fatty acids)

Question 34

What are the beneficial effects of omega 3 fatty acids?

Answer 34

inhibit production of leukotrienes (inflammation) and thromboxanes (platelet aggregation, thrombosis); promote production of prostacyclins (antithrombotic)

Question 35

What is the dietary requirement for protein?

Answer 35

0.6-0.8g/kg body weight

Question 36

What is pellagra?

Answer 36

disease of the 4 D’s - photosensitive dermatitis, diarrhea, dementia, death; caused by niacin deficiency (eg corn diet with no tryptophan, precursor to niacin)

Question 37

Transamination

Answer 37

transfers an amino group from an amino acid to a ketone producing a new amino acid and a keto acid

Question 38

What is the function of the alanine cycle?

Answer 38

alanine is produced by muscle to carry nitrogen from muscle protein breakdown to the liver where it is transaminated to make urea; the carbon is recycled as glucose

Question 39

Gout is caused by

Answer 39

uric acid crystals and resulting inflammation

Question 40

Gout can be treated with

Answer 40

allopurinol, a xanthine oxidase inhibitor; NSAIDs, and corticosteroids to treat the inflammation