The genetic information stored in DNA is transcribed into mRNA and then transformed into protein.
- Sigma factors enable RNA polymerase to bind to promoter DNA.
- TRNA polymerase allows the DNA to untwist then unzips, the hydrogen bonds between complementary DNA nucleotides break
- Free RNA nucleotides form complementary base pairs with one DNA strand (Template/ sense strand)
The unused strand is named the Antisense / coding strand – b/c it has the same coding as the mRNA
- Weak hydrogen bonds form between base pairs
- Sugar phosphate bonds form between RNA nucleotides
- mRNA strand is synthesized
- Hydrogen bonds of the untwisted RNA + DNA helix break, freeing the newly synthesized RNA strand.
- mRNA peels off the DNA and is small enough to move out of the nuclear pores into the cytoplasm
Translation takes place on the ribosome’s in the cytoplasm – the ribosome’s are the sites of protein synthesis
- The mRNA strand attaches to a ribosome and passes along it in short spurts of 3 nucleotides at a time so that it can be “read”.
- Each mRNA codon codes for a specific amino acid
- mRNA is decoded by a ribosome complex and signals are sent to induce the binding of tRNA to mRNA
- tRNA molecules transport specific amino acids to the ribosome that are chained together into a polypeptide
- The anti-codons in tRNA and codons in mRNA match up and form complementary base pairs
- Peptide bonds form between the adjacent amino acids to form the polypeptide (protein)
- A stop codon is finally met so the ribosomal complex falls apart and the protein is released into the cell
- tRNA is reused and collects another specific amino acid e.g. broken down into free nucleotides to be reused.