8.4 polypeptidesynthesis - transcription & splicing

Question 1

describe the process of transcription. (6)

Answer 1

1) DNA helicase unwinds & disrupts hydrogen bonds -> exposes nucleotide bases
2) 1 strand acts as template strand, while the other acts as a coding strand
3) free RNA nucleotides align with bases on template strands through complementary base pairing
4) RNA polymerase binds to promotor region & joins nucleotides together by phosphodiester bond -> pre-mRNA
5) DNA rewinds & base pairs behind RNA polymerase until terminator region
6) RNA polymerase detaches & transcription is completed

Question 2

in which way does RNA polymerase go?

Answer 2

3’ to 5’ (anti-sense)

Question 3

to which strand is pre-mRNA identical to and which base is the exception?

Answer 3

coding strand, except uracil

Question 4

in which way is pre-mRNA made?

Answer 4

5’ to 3’

Question 5

in prokaryotic cells, does splicing occur? why?

Answer 5

no as no introns

Question 6

how is pre-mRNA spliced?

Answer 6

introns removed from pre-mRNA & exons are spliced/ligated together using spliceosome