Protein Synthesis Human life is impossible without proteins. Why?

Proteins are of two Kinds

1. Structural 2. Functional Actin & Myosin: muscle proteins

Keratin: nails, hair, horns, feathers

Collagen: bones, teeth, cartilage, tendons, ligament, blood vessels, skin matrix

Enzymes

Antibodies

Haemoglobin

Protein Synthesis takes place on two major steps:

1. Transcription

2. Translation

Transcription:

Takes place inside the nucleus DNA unzips (one gene) and a complimentary copy of

this gene called mRNA (messenger RNA) is formed from RNA nucleotides

The newly formed mRNA leaves the nucleus through the a nuclear pore

Translation:

Takes place in the cytoplasm The freely floating ribosomes or the ones sticking to the RER start reading the message on the mRNA Reading the message takes place three nitrogenous bases at a time (triplets), each triplet is called a codon tRNA (transfer RNA) which is found in the cytoplasm has the appropriate anti-codon for each codon which is equivelant to one specific amino acid There are 20 different amino acids that enter in the synthesis of polypeptides (proteins)

Translation:

Mutations

1. Chromosomal mutations 2. Gene mutations

All or part of a chromosome. e.g.: Down's Syndrome

* Any of such mistakes results in a wrong protein being synthesized.

• Deletion: deletion of one nitrogenous base

• Addition: adition of one nitrogenous base

• Substitution: one nitrogenous base is replaced by another