KAL - Genetic Diseases

Question 1

How are genetic diseases caused by chromosmal abnormalitites?

Answer 1

Induced by errors in replication by physical or chemical agents

Question 2

What is known as a loss of a chromosome, and a gain of a chromosome?

Answer 2

Loss of a chromosome - Monosomy

Gain of a chromosome - Trisomy (Down syndrome)

Question 3

How are genetic diseases caused by single gene defects?

Answer 3

Small changes in the nucleotide sequence of DNA

Question 4

How does mutation effect the promoter region?

Answer 4

Increase/decrease in transcription → Protein excess/deficiency

Question 5

How does mutation effect the Intron/Exon boundaries?

Answer 5

Splicing errors → mRNA is longer or shorter than normal

Question 6

How does mutation effect the Coding areas of a gene?

Answer 6

Altered codon → Altered amino acid

Question 7

What are the 3 main spontaneous causes of mutation?

Answer 7

1. Replication Errors
2. Tautomeric Shifts- The bases of DNA are subject to spontaneous structural alterations called tautomerisation
3. Deamination- loss of amino group (base changes)

Question 8

What are mutagens?

Answer 8

External agents that can cause mutation

• Chemical or Physical

Question 9

What is an example of a chemical mutagen?

Answer 9

Intercalating agents (insert themselves between bases)

Question 10

What are examples of physical mutagens? (3)

Answer 10

Radiation, X-rays, U/V (act to break bonds and bases)

Question 11

How are genetic diseases tested for in adults/children? (2)

Answer 11

• Blood sample
• Skin biopsy

Question 12

How are genetic diseases tested for in a foetus? (2)

Answer 12

• Amniocentesis
• Chorionic villus sampling

Question 13

How are genetic diseases tested for in a embryo? (1)

Answer 13

Pre-implantation genetic diagnosis (PGD)

Question 14

How can chromosomal abnormalities be detected?

Answer 14

Chromosomes can be visualized through a light microscope with a Giemsa stain