1. Urwa
Mesret
3.5 Bio notes
Transcription is where the gene is converted into a mRNA
messenger which is posted to the ribosomes which occurs in
nucleus.
Translation occurs when ribosomes translate the message into
a polypeptide which occurs in the cytoplasm.
 The sequence of amino acids is determined by the
genes which are codes for making polypeptide.
DNA – double helix & Thymine pairs with Adenine
RNA- single strand & bases Uracil replaces Thymine
Transcription is where a polymerase makes a mRNA molecule
that is complementary to the DNA.
Translation is where mRNA is posted out of the nucleus and attaches to ribosomes. Ribsomes use
complementary base-pairing to ‘read’ codons on the
mRNA. tRNA transfer molecules with
corresponding anti- codons bring the correct
amino acid.
DNA is transcribed in triplets- sequence of three
bases which gives mRNA codons- sequence of
three RNA bases. mRNA codons make up genetic
code.
The genetic code: all living things use the same
code and same bases. Codons code for the same
amino acids. There are 64 codons but 20 amino
acids.