WEEK 6: PROTEIN: MACRONUTRIENT AND GENE PRODUCT

Question 1

Structure of protein

Answer 1

Polypeptides: long chains of amino acids
- Amino acids contain: amine group and a carbon skeleton including: carboxyl group, hydrogen and a side chain (determines the amino acid name, structure, function and its class (acidic, basic, branched)

Question 2

Essential amino acids

Answer 2

• must be provided by the diet
• there are 8 essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine

Question 3

Non-essential amino acids

Answer 3

• produced by body via transminatino of dietary amino acids at required rate
• there are 11 non-essential amino acids: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine

Question 4

Conditionally essential amino acids

Answer 4

• essential during infancy only (histidine), or during disease or trauma (glutamine and arginine)
• must come from diet at these times to meet requirements

Question 5

Factors determining amino acids essentiality

Answer 5

• cells cannot make the carbon skeleton of essential amino acids
• cells lack the enzyme to attach the amine group to the carbon skeleton to form the essential amino acids
• cells cannot achieve the manufacture of essential amino acids at a fast enough pace to meet requirements

Question 6

Deamination

Answer 6

• removal of amine group which then converts to ammonia which converts to urea in the urea cycle(in liver) which is filtered in kidney and excreted via urine
• occurs when amino acids are to be converted to pyruvate, acetyl CoA, intermediates of the CAC, or to oxaloacetate for gluconeogenesis

Question 7

Transamination

Answer 7

• transfer of an amine group from one amino acid to a carbon skeleton to form a new amino acid
• occurs when when additional non-essential amino acids are required in the AA pool. Occurs principally in the liver

Question 8

Enzymes and cofactors required in transamination

Answer 8

• transaminases: ALT and AST

- vitamin B6

Question 9

Complete dietary proteins

Answer 9

animal proteins (except gelatin) containing all 8 essential amino acids

Question 10

Incomplete dietary proteins

Answer 10

plant proteins (except quinoa and soy) which do not contain all essential amino acids or are low in 1 or more amino acids

Question 11

Complimentary dietary proteins

Answer 11

2 or more plant proteins can be combined to compensate for deficiencies in essential amino acids

Question 12

Limiting amino acid

Answer 12

the smallest supply of essential amino acid (lowest concentration of protein)

Question 13

Complimentary dietary protein examples

Answer 13

legumes: low in methionine and tryptophan
compliment with:
nuts/seeds: low in lysine
grains: low in lysine, isoleucine

Question 14

Amino acid pool

Answer 14

• essential amino acids required by the cell for the synthesis of gene products
• in liver

Question 15

Amino acids found in the amino acid pool (after absorption) are used for

Answer 15

• protein synthesis
• for energy production after deamination
• in gluconeogenesis after deamination