DNA

Question 1

What are nucleic acids?

Answer 1

Polymers of nucleotides.

Question 2

What are the components of a DNA nucleotide?

Answer 2

Deoxyribose, phosphate group, and one of the organic bases adenine, cytosine, guanine, or thymine.

Question 3

What are the components of an RNA nucleotide?

Answer 3

Ribose, phosphate group, and one of the organic bases adenine, cytosine, guanine, or uracil.

Question 4

What type of bases are adenine and guanine classified as?

Answer 4

Purine bases.

Question 5

What type of bases are thymine, uracil, and cytosine classified as?

Answer 5

Pyrimidines.

Question 6

How many nitrogen-containing rings do pyrimidines have?

Answer 6

One nitrogen-containing ring.

Question 7

How do nucleotides join together?

Answer 7

Via phosphodiester bonds formed in condensation reactions.

Question 8

What is the structure of a DNA molecule?

Answer 8

A double helix composed of two polynucleotides.

Question 9

How many hydrogen bonds are formed between adenine and thymine?

Answer 9

Two hydrogen bonds.

Question 10

How many hydrogen bonds are formed between cytosine and guanine?

Answer 10

Three hydrogen bonds.

Question 11

What is the structure of RNA?

Answer 11

Single-stranded.

Question 12

What are the different forms of RNA involved in protein synthesis?

Answer 12

mRNA, tRNA, and rRNA.

Question 13

What does semi-conservative replication of DNA ensure?

Answer 13

Genetic continuity between generations of cells.

Question 14

What is the role of DNA helicase in DNA replication?

Answer 14

Catalyses the unravelling of the DNA double helix.

Question 15

What happens during the second step of semi-conservative DNA replication?

Answer 15

Free nucleotides line up and complementary base pairing occurs.

Question 16

What catalyses the joining of adjacent nucleotides during DNA replication?

Answer 16

DNA polymerase.

Question 17

What is the significance of the term semi-conservative in DNA replication?

Answer 17

New DNA molecules contain one original strand and one newly-synthesised strand.

Question 18

Fill in the blank: The components of a nucleotide include a pentose sugar, a nitrogen-containing base, and a _______.

Answer 18

Phosphate group.

Question 19

What are codons?

Answer 19

Triplets of bases that code for an amino acid

Question 20

What is a polypeptide chain?

Answer 20

A chain formed by amino acids joined together by peptide bonds

Question 21

Define a gene.

Answer 21

A sequence of bases on a DNA molecule coding for a sequence of amino acids

Question 22

What are introns?

Answer 22

Non-coding regions of DNA

Question 23

What are exons?

Answer 23

Coding regions of DNA

Question 24

What does it mean that the genetic code is non-overlapping?

Answer 24

Each triplet is read only once and does not share bases with other triplets

Question 25

What does it mean that the genetic code is degenerate?

Answer 25

More than one triplet can code for the same amino acid

Question 26

How does the degeneracy of the genetic code reduce the effects of mutations?

Answer 26

A mutation may not affect the amino acid coded for if the new triplet still codes for the same amino acid

Question 27

What is a harmful mutation example mentioned in the text?

Answer 27

The mutation that leads to sickle cell anaemia

Question 28

What is a frameshift mutation?

Answer 28

A mutation that causes all downstream codons to be read differently

Question 29

What are start and stop codons?

Answer 29

Codons that either start or stop protein synthesis

Question 30

Is the genetic code universal?

Answer 30

Yes, it is the same in all organisms and species