Drug Effects on Nucleic Acids

Question 1

What are mutagens?

Answer 1

Man-made agents that alter the structure/sequence of genetic material so induce mutation

Question 2

Describe different types of mutagens

Answer 2

Chemical mutagens - Base analogs, Chemical modification agents, Intercalating agents
Radiation - Ionising radiation, UV radiation
Biological mutagens - Transposable element

Question 3

What are the different types of chemical mutagens?

Answer 3

Base analogs and Intercalating agents

Question 4

Describe base analogs

Answer 4

Molecules with similar structure to DNA bases so DNA poly can’t differentiate them from normal bases during DNA replication hence cause mutations

Question 5

Describe intercalating agents

Answer 5

Produce mutations by intercalating btw adjacent DNA bases, change 3D structure of helix causing frameshift via insertion/deletion in DNA replication

Question 6

Describe ionising radiation including examples

Answer 6

Ionises water to form radicals that break DNA strands so alter bases, More powerful than UV, Penetrates glass, Eg X-rays, Gamma-rays

Question 7

Describe non-ionising radiation

Answer 7

Causes covalent bonds to form btw adjacent T bases on same strand to form thymine dimers, Blocks replication/transcription, Eg UV rad
Note: If not repaired, thymine dimers can’t be replicated hence cause mutations (Thymine covalently bonding so in dna rep dna poly doesn’t recognise it so doesn’t repair and skips hence mutations occur)

Question 8

Describe biological mutations in terms of transposable elements

Answer 8

DNA sequences that move from locations in genome - Disrupts reading frame, loss of function

Question 9

What are alkylating agents?

Answer 9

Change base-pairing - Add ethyl/methyl groups (Point mutations)

Question 10

What are carcinogens?

Answer 10

Chemicals that cause cancer though DNA damage/interfering with cellular processes

Question 11

Name some disease treatable by agents that effect eukaryotic DNA

Answer 11

Cancers - Cytotoxic agents
Viral infections - Prevent virus replication
Protozoal infections - Prevent protozoan replication
Chronic inflammatory and autoimmune disease - Prevent lymphocytes proliferation Prevention of rejection of transplants - Immunosuppressant suppresses the immune system so it doesn’t attack ‘foreign cells’ identified due to transplant cells