Term 1 Reflection – Biomolecules

What interests me most about this topic is the sheer number of amino acids found in the body.

As such, I looked them up and put my findings here.


What I know from the syllabus

Amino Acids are the building blocks of proteins. There are 20 different types, which differ only by the R part of the structure.

Amino acids link together using peptide bonds through the process of condensation, creating many different varieties of proteins.

What else I found

When the body synthesizes protein, ammonia is formed in the liver as a waste product. Excessive protein in the diet can result in excess ammonia produced, stressing the liver and kidneys whose jobs are to flush it out of the body –> why eating too much meat is bad for your health

There are essential amino acids which cannot be manufactured by the body and must be taken in through the diet. These are generally found in soy, egg white, cheese, chicken and other protein-rich foods.

  1. histidine – (polar, basic) A precursor to histamine, which allows more WBCs to enter capillaries to engage pathogens during an immune response.
  2. isoleucine – (nonpolar) Hydrolyzes zein and edestin, proteins found in maize and hemp respectively.
  3. leucine – (nonpolar) Stimulates muscle protein synthesis and used in the formation of sterols.
  4. lysine – (polar, basic) Its derivative, allysine, is used in the production of collagen and elastin.
  5. methionine – (nonpolar) It is the only sulfur-containing amino acid besides cysteine. Reduces fat deposition in the liver, stimulates production of cartilage and strengthens hair and nails.
  6. phenylalanine – (nonpolar) The body changes it into tyrosine, which is needed to make brain chemicals such as dopamine and epinephrine (adrenaline).
  7. threonine – (polar) Helps in formation of collagen and elastin in skin. Also metabolizes fat.
  8. tryptophan – (slightly polar) Used to produce serotonin, a neurotransmitter important for normal nerve and brain functions.
  9. valine – (nonpolar) Needed for muscle metabolism, tissue growth and repair. [*In sickle-cell anemia, it takes the place of the hydrophilic glutamic acid in haemoglobin. As it is hydrophobic, it alters the shape of the RBC abnormally.]

The other 80% of amino acids can be manufactured by the body and thus classified as non-essential:

  1. alanine 
  2. arginine
  3. asparagine
  4. aspartic acid
  5. citrulline
  6. cysteine
  7. cystine
  8. gamma-aminobutyric acid
  9. glutamic acid
  10. glutamine
  11. glycine
  12. ornithine
  13. proline 
  14. serine
  15. taurine
  16. tyrosine

Because I don’t have a lot of time now, I will only be focusing on the essential amino acids for this post. Their polarity, acidity, natural sources and (very) summarized functions are as shown above.


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