Written by amberstudies

Life Sciences: Protein Synthesis

Hi

This is a post on protein synthesis which at first I did not understand at all but I tried to study it differently. Hopefully this helps some of you. Proteins are the “workhorses” of all living systems and this whole process is all to create proteins.

There are two parts to this process- transcription and then translation.

TRANSCRIPTION

  1. First, a gene (small piece of DNA) unwinds and the two strands unzip
  2. New nucleotides pair up with their complementary partner on ONE of the strands of DNA. This strand is known as the template because it carries the genetic code.
  3. The nucleotides join up to form a strand of mRNA and so we can see that the nucleotide sequence is determined by the sequence of the template of the DNA nucleotides. Therefore the DNA is transcribing its genetic code to the mRNA
  4. Note: a uracil base replaces the thymine base
  5. A completed strand breaks away from the DNA and the DNA rezips
  6. The small mRNA moves through the pores of the nuclear membrane and the genetic code is then carried by it to the ribosomes (site of protein synthesis)

SUM UP: Transcription is the process where mRNA is made and coded

WHAT HAPPENS NOW? WE’RE AT THE RIBOSOME

The mRNA binds to the ribosome at the start codon and the codons of the mRNA act as a template that determines the order in which the amino acids are linked.

TRANSLATION

  1. The anticodon (3 bases on the tRNA) link up to their complementary bases of the codon and the code is translated.
  2. Catalysed by enzymes, the amino acids link together by means of peptide bonds and the tRNA molecule is released to carry more specific amino acids to the ribosome.
  3. Therefore, the amino acids are linked up to a form a specific protein in an order corresponding to the sequence of codons in the mRNA which was coded by DNA

WHAT DETERMINES WHAT PROTEIN IS MADE?

The order that the amino acids are linked in will decide what amino acids are created. Various sequences will make the 20 different amino acids that are involved in protein synthesis.

BUT WHAT DETERMINES THIS ORDER?

This is all put into the sequence that the DNA template provided during translation.

  • The genetic code in DNA is passed on through a sequence of ‘codewords’
  • The DNA transcribes the genetic code to the mRNA
  • Each ‘codeword’ is made up of 3 bases which are known as a codon
  • Each codon codes for a specific amino acid. We know now then that each amino acid has a different code of 3 letters
  • The order of codons in mRNA will then determine the sequence of amino acids and thus the protein that is formed

A gene is made up of a group of codons (a lot of them) that code for the synthesis of one protein.

This was hopefully helpful, let me know

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