Introduction to DNA damage + mutations

Question 1

Mutant DNA sequences

Answer 1

• Can be beneficial, harmful or neutral
• Occurs from DNA damage or from inaccurate DNA repair

Question 2

What are mutations?

Answer 2

• Heritable changes in genetic material not due to genetic recombination
• Ultimate source of differences among species

Question 2

Most genetic variation is due to…

Answer 2

…genetic recombination and sex
- Reciprocal exchange of genetic material between homologous chromosome pairs
- Independent assortment of paternal + maternal chromosomes during meiosis ( 10^23 outcomes)

Question 3

Cause of inherited disease

Answer 3

• Most cases they are cause of cancer
• People have 1-2 recessive lethal mutations on average

Question 4

Mutational hotspots

Answer 4

• While mutations are random events that can occur at any point oof genome, there are certain DNA sequences that are hotspots

Question 5

Wild-type sequence

Answer 5

• ‘normal’ sequence prior to mutation
• due to variation in population, it’s hard to define
• Often chosen arbitrarily + used as a reference
• For disease genes, WT tends to be non-diseased gene

Question 6

Types of mutations

Answer 6

• Single nucleotide variants
• Block substitutions - more than 1 bp changes
• Insertions + deletions
• Inversions - stretch of DNA is flipped
• Copy number variants

Question 7

Mutations - Rearrangements

Answer 7

• Extensive chromosomal alterations with 1000s of bps or a whole chromosomes