DNA transcription and translation

Question 1

what is transcription?

Answer 1

synthesis of RNA under direction of DNA and it produces mRNA

Question 2

what is translation?

Answer 2

synthesis of a polypeptide which occurs under direction of mRNA. ribosomes are the site of this

Question 3

what are introns and exons?

Answer 3

introns: “non-coding” regions of DNA are removed by RNA processing (splicing) so they aren’t expressed by final mRNA
exons: sequence of DNA that are joined to form mature mRNA and are translated into protein

Question 4

what is a codon?

Answer 4

base triplet (any of ATCG)
there are 64 triplets (61 code fro amino acids, 3 triplets are stop codons)

Question 5

what happens in translation?

Answer 5

initiation: transcription factor binds to promotor region, DNA helices unwinds the gene breaking the hydrogen bonds, RNA polymerase binds just before the starting codon of the gene
elongation: RBA polymerase transcribes mRNA from 5’ to 3’ direction
termination:RNA polymerase recognises the termination signal leaving behind pre-MRNA

Question 6

what happens in post-transcription splicing?

Answer 6

remove introns from pre-mRNA to form mRNA and this will travel out of the nucleus to the cytoplasm where it will bind to a ribosome

Question 7

What happens in translation?

Answer 7

initiation: protein synthesis, translation begins at start codon. when mRNA binds to ribosome a tRNS molecule (carrying a specific amino acid) will recognise the start codon and will bind to its anticodons (bases in tRNA anticodon are complimentary to the bases in mRNAs codon)
elongation: a second tRNA molecule binds aswell with an amino acid. a peptide bond will form between the two amino acids. this repeats
termination: there are no tRNA molecules with anticodons corresponding to a stop codon so once they reach it the synthesis is terminated