Genetics

Question 1

Which organelle contains ds circular DNA

Answer 1

Mitochondria
mDNA expressed in mitochondria rich tissues-muscle, neural tissue, myocardium-so susceptible to myopathy and cardiopathy
DNA in the mitochondria code for enzymes involved in oxidation and energy production.

Question 2

Most common ds associated with trinucleotide repeat expansion?

Answer 2

Fragile X

Others :Myotonic dystrophy
Huntington chorea
Friedreich ataxia
Spinocerebellar ataxia
Spinobulbar muscular atrophy
Machado-Joseph ataxia

Question 3

Missense vs non sense mutation?

Answer 3

Missense: Single nucleotide change resulting in different amino acid
Non sense: Single nucleotide change resulting in stop codon

Question 4

What is genetic fingerprinting?

Answer 4

Detection of variable number of tandem repeats(VNTR)- highly polymorphic sequences of DNA-pattern on blotting is unique for each individual

Question 5

Inheritance of Huntington’s Disease?

Answer 5

HD is an AD Triple repeat mutation with expansion of CAG (glutamine) triplets
Manifests in middle age
Most severe if transmitted through paternal line and more likely to lead to anticipation with younger age of onset

Question 6

What are trinucleotide repeat expansion disorders?

Answer 6

Three base pair sequence that repeats-usually less than 35 repeats
May expand into mutant range, become stable to >50
Type I involves expansion in a regulatory area, type II does not.
Anticipation seen in successive generations