Proteins are made from different types of amino acids and are made in ribosomes in the cytoplasm of a cell. To make a protein, a copy of our DNA because the genes code for proteins and the copies come out of the nucleus , where the DNA is, into the cytoplasm and to a ribosome.

TRANSCRIPTION

Transcription is when a gene is 'unzipped' so that the hydrogen bonds that join the bases are broken. One strand of the double helix is copied with the complementary bases and where there should be a thymine base, a uracil base is put. This strand is the messenger RNA and is a single strand of DNA with uracil instead of thymine.

In the nucleus, RNA polymerase attaches to the non-coding section of DNA and the enzyme separates the two strands
RNAp continues to move along the DNA until it gets to the coding section of a gene
RNAp adds complementary RNA nucleotides to the template strand
RNAp links the RNA nucleotides together to form a strand of mRNA
The mRNA travels out of the nucleus through a nuclear pore

TRANSLATION

Translation is when the mRNA is joined to a ribosome and each 3 bases, called a codon, are translated so that transfer RNAs can bring one of 20 amino acids to that codon. This happens for every codon, and the amino acids form a long chain called a polypeptide. This then folds itself up, according to the amino acids used, to form a protein.

In the cytoplasm, a ribosome and mRNA strand attach together
A tRNA molecule pairs up with each codon
The ribosome joins together the amino acids carried by the tRNA molecules
This results in the formation of a polypeptide
The types and order of amino acids in the chain cause it to fold into a specific shape, forming a protein

	Erstellt von Fatima Hussain vor mehr als 8 Jahre

Year 10 Biology Folienset am Edexcel 9-1 GCSE Biology B3 Summary; Genetics, erstellt von Fatima Hussain am 21/04/2018.