Exam 15: Gene Mutation and Molecular Medicine

Suppose that the DNA change associated with a cholesterol metabolism disease is discovered and this discovery leads to the identification of the causative enzyme.This process would be an example of

The isoenzyme hexosaminidase A (HEXA), composed of subunits α and β, breaks down molecules containing terminal N-acetyl hexosamines.Tay-Sachs disease is caused by a recessively inherited mutation in the gene coding for the α subunit, which is the subunit that hydrolyzes the lipid GM2 ganglioside.Accumulation of this lipid in the brain leads to progressive deterioration of the nervous system and death, usually by age 4.A child born homozygous for the loss-of-function α subunit allele nevertheless does not develop Tay-Sachs disease.Sequence analysis of the β subunit alleles reveals that one allele has a mutation that makes it able to hydrolyze GM2 ganglioside.This is a _______-of-function mutation, which is most likely _______.

Flour beetles with a mutation raised at 25°C appear normal, but if these beetles are raised at 32°C (a temperature that wild-type beetles easily tolerate), they have limb deformities.For this mutation, 25°C is a _______ temperature.

People with PKU are treated

Which disease is routinely treated by supplying the patient with a missing protein?

Parkinson's disease is caused by inadequate production in the brain of the neurotransmitter -aminobutyric acid (GABA), which is synthesized by the enzyme glutamate decarboxylase.Adeno-associated virus has been used in therapy clinical trials to treat Parkinson's disease.In these trials the virus has _______ into brain cells.

Deamination, which can lead to mutation if it occurs in one of the bases of DNA, is the _______ of a(n) _______ group.

A couple are heterozygous for Tay-Sachs, a rare autosomal recessive disease that is fatal in infancy and results when a baby inherits two nonfunctional alleles of HEXA, the gene for the enzyme hexosaminidase A.The couple wants to ensure that the mother only becomes pregnant with a fertilized egg that is homozygous HEXA normal.A _______ screening test would best ensure that she did not become pregnant with another HEXA genotype.

A researcher has identified a gene linked to a neurodegenerative disease.In individuals that suffer symptoms of this disease, at a specific location within this gene the sequence CAG is repeated many times more than it is in unaffected individuals.This disease exemplifies the phenomenon of _______.

A gene for a clotting factor is inserted into the fertilized egg of a dog.This is an example of

Concerned about a skin mole that has increased in size and darkened in color, a man visits a dermatologist.Based on a biopsy, the mole is diagnosed as melanoma, a form of cancer.A genomic analysis reveals a mutation in the BRAF gene, a commonly mutated gene in melanoma.The BRAF gene is the wild type in surrounding noncancerous cells.These data are evidence that