Transcription

Question 1

Two stages of protein synthesis:

Answer 1

Transcription then translation

Question 2

Steps pre transcription

Answer 2

A section of dna is copied and used to make a complementary strand on mRNA.
One of the DNA strands is used as a template to form mRNA, it is known at the template strand.
Nucleotides attach to the mrna strand according to rna base pairing rules.
Length of dna opposite template strand is coding strand which is t instead on u.

Question 3

Process of transcription

Answer 3

1. An enzyme called rna polymerase binds to a sequence of nucleotides that signal the starting point of transcription
   This enzyme causes bonds between complementary base pairs to break. This unwinds the two strands of DNA.
2. RNA polymerase then moves along part of the gene that contains the sequence of bases required for a protein to be built. As it moves along the bases, it takes free nucleotides and adds them to the growing mrna strand.
3. Eventually RNA polymerase reaches a sequence of bases that signal the end point of the transcription process. Transcription is complete. DNA double helix reforms and the mrna detaches from the rna polymerase. Mrna moves out of nucleus through nuclear pores.
   Once mrna reaches ribosomes in cytoplasm, translation can begin.

Question 4

Transcription produces a….

Answer 4

Copy of dna that can leave the nucleus and carry genetic information to the ribosomes in the cells cytoplasm. Dna master copy doesn’t leave nucleus and isn’t damaged. If Mrna is damaged molecule will keep making more. Mrna is single stranded so it fits easily through nuclear pore.