Transcription

Question 1

Transcription - Step 1

Answer 1

DNA in region of a gene unwinds & unzips

Nucleotide on both sides exposed

Question 2

Transcription - Step 2

Answer 2

One strand is used to direct synthesis of mRNA (U replaces T) - template strand
Other strand, same sequence as mRNA (T bases not U) - complimentary strand

Question 3

Transcription - Step 3

Answer 3

Promoter - Particular nucleotide sequence at beginning of a gene, signals the start of a gene
Proteins position RNA polymerase on DNA to bind with promoter

Question 4

Transcription - Step 4

Answer 4

Complimentary RNA nucleotides joined together by RNA polymerase moving along length of DNA
Base sequence at end of gene = stop signal, mRNA released as single strand

Question 5

Transcription - Step 5

Answer 5

DNA zips up & twists itself into double helix again once mRNA has peeled off

Question 6

Transcription - Step 6

Answer 6

Intron - section of DNA that doesn’t encode a protein sequence
Exons - coding regions, contain info for protein formation
Introns spliced before mature mRNA leaves nucleus

Question 7

Transcription - Step 7

Answer 7

Mature mRNA ready to leave nucleus and move to cytoplasm, where translation of nuclear code is carried out by ribosomes