Transcription and translation



1. RNA polymerase attaches to DNA. This causes hydrogenm bonds to break meaning the DNA unzips and uncoilds seperating the two strands. One strand used as a template. 

2. Activated RNA  free nucleotides binds with hydrogen bonds, to their exposed complemetary bases. 

3. Two extra phosphates are released producing energy for bonding adjacent nucleotides. 

4. RNA polymerase moves along assemblying the mRNA, the hydrogen bonds between the DNA strands reform once rna polymerase has passed. 

5. when rna polymerase reaches stop codon it stops making mRNA and detached from the DNA 

6. the mRNA moves out of the nucleus through nuclear pores and attaches to a ribosome in the cytoplasm. 

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1. mRNA attaches itself to a ribsome. two codons are attached to the small sub unit and exposed to the large sub unit. the first codon is always AUG. using ATP, tRNA comes with the anticodon UAC and binds forming hydrogen bonds wiht this codon 

2. a second tRNA with different amino acid, binds to the second exposed codon with complementary anticodon. 

3. a polypeptide bond forms between two adjacent amino acids. an enzyme in small sub unit catalyses this reaction 

4. ribsome now moves along mRNA reading the nmext codon and a third tRNA comes with another amino acid and a peptide bond forms. the first tRNA leaves and is able to collect and bring another amino acid. 

5. the polypeptide chain grows until it reaches the stop codon. 

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