Protein Synthesis | Genetics and Evolution - Biology IB23

Protein Synthesis

DNA is the holder of codes responsible for protein synthesis.

Transcription Summary

Makes a copy of a gene on DNA to turn into a molecule of RNA.

Transcription Steps

1. Happens in the nucleus.

2. Enzyme RNA polymerase is needed to open the hydrogen bonds between the double-stranded DNA which makes a strand of mRNA next to one of the DNA strands.

3. RNA nucleotides are already present in the nucleus and places the nitrogenous bases into complementary pairs.

   C —> G | A —> U

4. The mRNA leaves the nucleus and the DNA goes back together.

Translation Summary

Translates the code on mRNA into amino acids in correct order.

Translation Steps

1. Happens on the ribosomes in the cytoplasm.

2. mRNA has the code copy of DNA and goes to the ribosome.

3. The code is read in groups of three nitrogenous bases called codons.

4. tRNA reads the code and brings the correct amino acid to the ribosome for each codon. tRNA has a complementary anticodon which will bind with the mRNA codon.

5. When two tRNAs are in the ribosome a peptide bond will form between the amino acids and the chain will further longate.

6. The ribosome will move further along the mRNA until it hits a certain codon. All parts will separate and the protein can leave the ribosome.