DNA & RNA

Question 1

Describe the structure of DNA.

Answer 1

Double helix made up of phosphate, deoxyribose and bases

Question 2

Which bases bind to which ones?

Answer 2

Purines bond with pyrimidines
A - T
G - C

Question 3

How many H bonds form between the bases?

Answer 3

A - T 2 H bonds

G - C 3 H bonds

Question 4

What are nucleosomes?

Answer 4

DNA wrapped around histone proteins

Question 5

What’s the difference between RNA and DNA structure?

Answer 5

Single stranded
Ribose instead of deoxyribose
Uracil replaces thymine

Question 6

What’s the difference between RNA and DNA function?

Answer 6

DNA is the blueprint of biological guidelines that a organism must follow to exist.

RNA transfers genetic code needed for the creation of proteins from the nucleus to the ribosomes.

Question 7

What is DNA replication?

Answer 7

Producing 2 identical replicas from 1 original DNA molecule

Question 8

Describe the steps of DNA replication.

Answer 8

Breaking of hydrogen bonds between bases of strands by HELICASE

RNA POLYMERASE constructs an RNA primer which guides DNA POLYMERASE to its site of action

DNA POLYMERASE joins the free nucleotides to the bases of the parent strand, creating a new strand

DNA LIGASE joins the old and new strand together

Question 9

Which way does DNA polymerase read the exposed DNA?

Answer 9

From 3’ to 5’

Question 10

Why is DNA replication referred to as semi-conservative?

Answer 10

Only one strand of the daughter strand is newly synthesised

One is conserved from the parent strand

Question 11

What is transcription?

Answer 11

DNA to mRNA

the mRNA can then be used to make a protein!

Question 12

Describe transcription.

Answer 12

RNA POLYMERASE separates the two strands of DNA and binds to the promoter region on one strand

It then adds matching RNA nucleotides to the complementary nucleotides of one DNA strand

It then helps to form the sugar-phosphate backbone

An mRNA strand is formed!

Question 13

Which direction does transcription go in?

Answer 13

5’ to 3’ direction

Question 14

Name 3 post-transcriptional modification processes

Answer 14

5’ capping
Polyadneylation
Splicing

Question 15

What is 5’ capping?

Answer 15

The 5’ capping reaction replaces the triphosphate group at the 5’ end of the RNA chain with a special nucleotide referred to as the 5’ cap.
Helps with mRNA recognition by the ribosome during translation

Question 16

What is polyadenylation?

Answer 16

A modification that takes place on the 3’ end of the RNA.

A poly A tail is added

Question 17

What is splicing?

Answer 17

Editing introns out of the RNA

Question 18

What is an exon and intron?

Answer 18

Exon - section that codes for a protein

Intron - section that doesn’t code for anything

Question 19

Where does transcription take place?

Answer 19

Nucleus

Question 20

Where does translation occur?

Answer 20

Cytoplasm

Question 21

What is translation? Describe it!

Answer 21

mRNA to protein

Ribosome assembles around the target mRNA. The 1st tRNA is attached as the start codon

The tRNA transfers an amino acid to the tRNA corresponding to the next codon

The ribosome moves to the next mRNA codon to continue the process, creating a chain

Stops when a stop codon is reached

Question 22

What is a codon?

Answer 22

3 base pairs in a row which code to make 1 amino acid - AGC for example

Question 23

What’s a nonsense mutation?

Answer 23

A mutation that results in a premature stop codon

Results in a truncated, incomplete and non-functional protein

Question 24

What’s a missense mutation?

Answer 24

A mutation where a single nucleotide change results in a codon that codes for a different amino acid