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