RNA

Question 1

Name the four bases that are found in RNA.

Answer 1

Prymidine: uracil, cytosine
Purine: adenine, guanine

A-U
G-C

Question 2

How is mRNA structured?

Answer 2

In mRNA, the RNA nucleotides are arranged to form a single stranded helix.

Question 3

What is the purpose of mRNA

Answer 3

mRNA acts as a messenger. It carries information from the DNA in the nucleus out to the ribosomes. At this location, the mRNA is used for proteinsynthesis.

Question 4

During transcription, what will mRNA make a copy of?

Answer 4

The mRNA strand is a copy of the non-template DNA strand, with uracil replacing thymine.

Question 5

What is the first step of transcription?

Answer 5

RNA polymerase breaks the hydrogen bonds between DNA bases, breaking the two strands apart and exposing the bases on each strand.

Question 6

What is the second step of transcription?

Answer 6

RNA polymerase adds RNA nucleotides to complementary bases on one strand.

Question 7

What are the roles of RNA polymerase

Answer 7

• Breaks the hydrogen bonds between RNA bases.
• Adds RNA nucleotides to complementary bases on one strand of DNA, known as the template strand.
• Attaches two strands of the DNA helix together.

Question 8

What is a codon?

Answer 8

a set of 3 bases on mRNA that codes for an amino acid.

Question 9

State 3 key features of the genetic code on mRNA.

Answer 9

• Degenerate: This means that multiple different codons can code for the same amino acid.
• Non-overlapping: This means that there is no overlap between codons when they are read: each part of the triplet is only read once.
• Universal: This means that all living organisms use the same genetic code; each triplet codes for the same thing in any organism.

Question 10

What is an anticodon?

Answer 10

a set of 3 bases that are complementary to a codon on mRNA. The anticodon is attached to a molecule that carries an amino acid.

Question 11

How does translation occur

Answer 11

• Codon arrives at the ribosomes and binds to them.
• A complementary anticodon with an amino acid attached bind to the start codon
• Ribosomes join the amino acids and bonds them together via condensation reaction forming a peptide bond
• First anticodon leaves so another one may join
• Repeats until the end codon to form a polypeptide chain

Question 12

Describe the structure of a tRNA

Answer 12

• Single strand of RNA
• Has a clover shape held together by hydrogen bonds between base pairs
• Has an anticodon
• Has an amino acid binding site

Question 13

What is rRNA

Answer 13

an RNA that forms ribosomes