Protein - Amino Acids:

Question 1

Amino Acids: Protein synthesis

Answer 1

• The human body uses 20 amino acids coded for in our genetic code for protein synthesis.
• Amino acids can form proteins with roles as diverse as providing skeletal muscle (all essential amino acids are needed for this) through to antioxidant synthesis (glutathione synthesis requires just three: cysteine, glutamic acid, and glycine).

Question 2

Amino Acid: Essential and Non essential

Answer 2

1. More than half of the 20 amino acids (AA) used by the body are considered non-essential; the body can synthesise them.
2. There are 9 AA’sthat humans cannot synthesise either in sufficient quantities or at all, so they must be supplied in the diet; they are termed essential.
3. Sometimes non-essential amino acids can become essential under specific circumstances, i.e. conditionally essential.
4. Animal-sourced protein contain all 9-essential amino acids, and are hence considered a ‘complete protein’.
5. A vegan/vegetarian diet can supply all essential amino acids when a variety of legumes, grains, nuts and seeds are consumed in a day (Diet for a Small Planet -by Frances Moore Lappé (introduced idea of combining veggie-food proteins)

Question 3

Non Essential Amino Acids

Answer 3

Non-essential Amino acids can be synthesised by the body. They include:
* Alanine
* Aspartic acid
* Glutamic acid
* Serine
* Asparagine

Question 4

Essential Amino Acids

Answer 4

Essential Amino Acids: Amino acids that humans cannot synthesise either in sufficient quantities or at all, so they must be supplied in the diet. There are 9:
* Phenylalanine
* Valine
* Threonine
* Tryptophan
* Isoleucine
* Methionine
* Histidine
* Leucine
* Lysine

Question 5

Conditionally Essential Amino Acids

Answer 5

Sometimes non-essential amino acids can become essential under specific circumstances, and are called conditionally essential.
* Arginine
* Cysteine
* Glutamine
* Glycine
* Proline
* Tyrosine

Question 6

Mnemonic for Essential Amino Acids

Answer 6

To remember your Essential Amino Acids:
* PVT TIM HiLL (Phe, Val, Thr, Try Iso, Met, His, Leu, Lys)

Question 7

8 or 9 Essential Amino Acids, and Histidine

Answer 7

• It’s debated as to whether the correct number of essential amino acids is 8 or 9.
• Today, most experts say 9, which includes histidine since it’s not synthesized in adults.
• However, bacteria can produce histidine, although its not clear how much of our need is provided by intestinal bacteria.
• Histidine is also the only amino acid that does not appear to impair protein synthesis when it is deficient in the diet so that seems to make it non-essential in nature.
• As a result, some regard histidine as “conditionally essential” and some continue to exclude it completely. Resources will vary.