Key Area 3

Question 1

What 3 types of RNA do translation and transcription involve

Answer 1

mRNA tRNA rRNA

Question 2

Describe RNA

Answer 2

RNA is single stranded and is composed of nucleotides containing ribose sugar, phosphate and 1 of 4 bases: cytosine, guanine, adenine and uracil (there is no Thymine in RNA uracil replaces this)

Question 3

What does mRNA do

Answer 3

mRNA /messenger RNA carries a copy of the DNA code from the nucleus to the ribosome

Question 4

What is the triplet of bases on the mRNA molecule called

Answer 4

Each triplet of bases on the mRNA molecule is called a codon and codes for a specific amino acid

Question 5

What does tRNA do

Answer 5

tRNA fold due to complementary base pairing. Each tRNA molecule carries its specific amino acid to the ribosome

Question 6

What does the tRNA molecule have at one end

Answer 6

TRNA molecule has a anticodon (an exposed triplet of bases) at one end and an attachment site for a specific amino acid at the other end

Question 7

What is rRNA used for

Answer 7

rRNA Is used alongside proteins to form the ribosome

Question 8

What happens during transcription

Answer 8

During transcription an mRNA ‘copy’ of a section of single stranded DNA is produced to travel from the nucleus to the ribosome.

Question 9

Transcription process

Answer 9

The enzyme RNA POLYMERASE moves along DNA UNWINDING the double helix and
breaking the hydrogen bonds between the bases

RNA Polymerase synthesises a PRIMARY mRNA TRANSCRIPT from RNA Nucleotides by complimentary base pairing

Question 10

What is RNA splicing

Answer 10

RNA splicing is when introns ( non-coding DNA which is transcribed) are removed from the primary mRNA Transcript as they do not contain info required to produce a protein

Question 11

What happens after non-coding introns are removed ?

Answer 11

Exons which are the coding regions join together

Question 12

What is alternative RNA splicing

Answer 12

Different proteins being expressed form 1 gene

Question 13

What joins the amino acids together during translation

Answer 13

Peptide bonds

Question 14

How does the genetic code get translated into a sequence of amino acids

Answer 14

Anticodons bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids

Question 15

Process of translation

Answer 15

Translation begins at a START CODON and ends at a STOP CODON.
Anticodons bond to Codons by complimentary base pairing, translating the genetic code into a sequence of Amino Acids.

Peptide Bonds join the amino acids together.
Each tRNA then leaves the Ribosome as the Polypeptide is formed.

Question 16

How are polypeptides formed

Answer 16

Amino Acids are linked by PEPTIDE BONDS to form POLYPEPTIDES.

Question 17

What do polypeptide chains fold to form?
What is it held together by?

Answer 17

Polypeptide Chains FOLD to form the 3-Dimentional shape of a Protein, held together by HYDROGEN BONDS

Question 18

What factors influence phenotype

Answer 18

Environmental factors

Question 19

What is phenotype determined by

Answer 19

Phenotype is determined by the proteins produced as the result of Gene Expression