2.6. Consequences of mutations

Question 1

DNA:

Answer 1

• double helix formation
• sugar phosphate backbone
• four bases A,C,G,T
• found in nucleus, mitochondria

Question 2

RNA:

Answer 2

• single stranded molecule
• uracil replaces thymine
• found in nucleolus and cytoplasm

Question 3

what is a mutation?

Answer 3

• a change in a genomic sequence
• Can be a single base, or duplication of entire segments or chromosomes
• NOT ALWAYS PATHOGENIC (disease-causing)
• It’s a matter of how RARE it is

Question 4

what are possible consequences of a mutation?

Answer 4

1. Silent (no effect)
2. Beneficial (good effect)
3. Deleterious (bad effect)

Question 5

list the Exogenous (outside of the cell) causes of mutations

Answer 5

1. Chemicals
2. Radiation
3. Pollutants

Question 6

list the endogenous causes of mutations

Answer 6

1. Spontaneous damage
2. Replication and recombination errors
3. Repair errors

Question 7

how often do mutations occur?

Answer 7

1. In humans and other mammals, uncorrected errors (= mutations) occur at the rate of about 1 in every 50 million(5 x 107) nucleotides added to the chain.
2. But with 6 x 109nucleotides in a human cell, that means that each new cell contains some 120 new mutations (EXCLUDINGexogenous causes of mutation).
   * Most of these mutations will be in non-coding regions

Question 8

STATIC variants

Answer 8

–do not change when passed to offspring

1. Point mutations (single nucleotide substitutions)
2. Deletion / Insertion mutations
3. Splice site mutations