Transcription And Translation Flashcards
What’s the first stage of protein synthesis
Transcription
Explain the start of translation
RNA polymerase attaches to the DNA at the beginning of a gene.
Hydrogen bonds break, separates strands because of DNA helicase. DNA uncoils.
One strand is used as a template strand to make mean copy.
Explain the middle of transcription
RNA polymerase lines up free rna nucleotides along template strand by complementary base pairing.
Once this is done they are joined together forming an mRNA molecule.
RNA polymerase moves along dNA separating the strands and assembling mRNA strand.
Explain the end of transcription
Hydrogen bonds between uncoiled strands reform once RNA polymerase has passed by and DNA coils back into double helix.
RNA polymerase reaches stop codon. Stops making mRNA and detached from DNA.
mrna moves out of nucleus through nuclear pore and attaches to ribosomes in cytoplasm.
What is the second stage of protein synthesis
Translation
What is the start of translation
mRNA attaches to ribosome. tRNA molecules carry amnio acids to ribosome.
Trna have anticodon which is complementary to start codon on mRNA attaches itself by complementary base pairing.
Second tRNA attaches itself to the next codon in same way.
Middle of translation
Ribosomal RNA in ribosome catalyses formation of peptide bond between two aminoacida between two tRNA molecules.
First tRNA moves away leaving amnio acid behind.
Third tRNAbinds to next codon on mRNA. Its amnio acid binds to first 2 and second tRNA moves away.
End of translation
Process continues. Producing a poly peptide chain. Until there is a stop codon on the mRNA molecule.
Polypeptide chain moves away from ribosome and translation is complete.
Eukaryotes during transcription
Complex of protein including DNA helicase that separates strands.
DNA template strand is also called
Anti sense strand.
