Module 1 - Part 2

Question 1

How do point mutations happen

Answer 1

• most common base pairing occurs btween A:T and G:C
• rare base pairing CAN occur between A:C and G:T due to tautomeric shifts

Question 2

Tautomer

Answer 2

a transient (non-permanent) isomeric form of a nitrogenous base

Question 3

Point mutation in sickle cell anemia

Answer 3

• an inherited disorder of RBCs involving the HBB gene
• encodes for B-globin protein
• hemoglobin: a tetramer formed of 2 alpha/beta global subunits
• HBB gene undergoes mutation - glutamic acid to valine at position 6

Question 4

frameshift mutation

Answer 4

insertion or deletion of one or several bases that may change all or part of the open reading frame (indels)
- changes polypeptide seq of protein

Question 5

Indels

Answer 5

change the open reading frame & DNA seq

Question 6

Small indels

Answer 6

• replication slippage results in addition/omission of a nucleotide
• DNA regions w many copies of repeated seq are most susceptible

Question 7

Large indels

Answer 7

• several hundred to thousands of nucleotides

Question 8

Trinucleotide repeats

Answer 8

3 nucleotides that’re repeated several times in succession
- not a mutation (but prone & considered a hotspot)
- repeated a few to 50 times

Question 9

Expanded trinucleotide repeats

Answer 9

A type of insertion that arises due to replication slippage in regions of the genome w TR

Question 10

Huntingtons Disease

Answer 10

Progressive neurodegenerative disorder characterized by:
- involuntary movements, declines in cog func, altered mood
- caused by expanded CAG trinucleotide repeat on chromosome 4
- pathological # of CAG repeats (>35)

Question 11

Anticipation

Answer 11

• a genetic phenomenon in which a disorder worsens with each generation
• arises due to replication error during the production of gametes