Biology-gene Expression

Question 1

What are the 3 differences between DNA and RNA

Answer 1

DNA has:
Double stranded
Deoxyribose sugar
Bases-A T C G

RNA has:
Single stranded
Ribose sugar
bases-A U C G (uracil)

Question 2

What is DNA in the nucleus transcribed to produce

Answer 2

messenger RNA- which carries a a copy of the genetic code

Question 3

What happens in transcription

Answer 3

RNA polymerase moves along DNA unwinding the double helix and breaking the hydrogen bonds between bases. RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complemtary base pairs

Question 4

What is RNA polymerase

Answer 4

It’s the enzyme responsible for transcription of DNA into primary mRNA transcripts

Question 5

What are non coding regions called

Answer 5

Intronds, whilst in a eukaryotic gene not all regions are required to produce the final protein

Question 6

What is transcription

Answer 6

It is the synthesis of mRNA from a section of DNA to transport the code from the nucleus to the cytoplasm

Question 7

What are coding regions called

Answer 7

Exons

Question 8

What happens when the mRNA has been transcribed

Answer 8

The introns are removed. The remaining exons are spliced together to form a continuous sequence. This is called the mature transcript. The mature transcript then leaves the nucleus to travel to the cytoplasm

Question 9

What is translation

Answer 9

It’s the synthesis of protein following the code within the mature mRNA transcript. This happens at the ribosome.

Question 10

What is mRNA made out of

Answer 10

Sequences of three nucleotides called codons

Question 11

What is transfer RNA

Answer 11

A type of RNA found in the cells cytoplasm, it’s called tRNA and is made out of a single chain of nucleotides, it’s folded into a 3d shape and is held together by hydrogen bonds

Question 12

What is the role of tRNA

Answer 12

Each tRNA has an attachment site for a specific amino acid and a codon. The tRNA picks up it’s appropriate amino acid and takes it to the ribosome to be matched with the mRNA

Question 13

What is the ribosomes purpose

Answer 13

It’s function is to bring tRNA molecules bearing amino acids in contact with the mRNA for protein synthesis

Question 14

What is the process of translation

Answer 14

1)the ribosome binds to the 5’ end of the mRNA so that the start codon is in position
2)a tRNA carrying the amino acid becomes attached to the ribosome
3)the mRNA codon temporarily bonds to the comp anticodon
4)a peptide bond then forms between these two amino acids
5)the ribosome then moves along one codon
6)the tRNA is released
7)steps 3-6 then repeat until it reaches a stop codon