Transcription and Translation 2.1.3 (g) Flashcards
what is transcription?
the process of copying the base sequence of a gene in DNA so that it can leave the nucleus
outline transcription
DNA helicase breaks the hydrogen bonds between bases which separates the two strands apart starting at the start codon
the anti-sense strand acts as the template with free RNA nucleotides pairing up with their base pairs
RNA polymerase forms phosphodiester bonds between the RNA nucleotides to reform the sugar-phosphate backbone
transcription stops at the stop codon
DNA double helix reforms
final product is a single strand of mRNA
role of RNA polymerase
forms phosphodiester bonds between adjacent RNA nucleotides
what is the sense strand?
the strand of DNA you are trying to make a copy of
what is the anti-sense strand?
the strand of DNA which allows you to make a copy of the sense strand
where does translation occur?
at the ribosomes in the cytoplasm or RER
what catalyses translation?
rRNA
outline translation
mRNA binds to the ribosome
tRNA contains the anti-codon which binds to the complimentary codons in the mRNA
the tRNA carry an amino acid which corresponds to the specific codon
amino acids brought one at a time by the tRNA and eventually a sequence of amino acids forms
peptide bonds form between adjacent amino acids which leads to the formation of a polypeptide
the polypeptide is released after the stop codon is reached
what are the three types of RNA involved in protein synthesis?
tRNA
rRNA
mRNA
role of tRNA
carries the amino acid which corresponds to the codon in the mRNA
corresponding codon identified by the use of the anti-codon finding it’s complimentary base pair
role of rRNA
makes up the subunits in ribosomes
they catalyse the formation of peptide bonds between adjacent amino acids in translation
role of mRNA
carries a copy of the complimentary strand of DNA which is synthesised during transcription
small enough to leave through the nuclear pores in the nuclear envelope
