GENE PROBES AND MEDICAL DIAGNOSIS

Question 1

dna probe

Answer 1

dna probes are short strands of dna which has a specific base sequence complementary to the base sequence of a part of a target allele ( allele that causes a genetic disorder)

Question 2

labelling of dna probes

Answer 2

dna probe has a label attatched so that it can be detected. label is either a radioactive label which is detected using a x ray or either a fluorescent label ( detected using uv light)
- if allele is present, dna probe will hybridise to it.

Question 3

gene therapy

Answer 3

• involves altering the defective genes inside cells to treat genetic disorder and cancer.

Question 4

disorder caused due to two mutated recessive allele

Answer 4

• a working dominant allele is added to make up for the faukty recessive alleles.

Question 5

disorder caused due to mutated dominant allele

Answer 5

• the dominant allele is silenced by sticking a dna in the between of the allele so it doesnt work anymore.

Question 6

types of gene therapy

Answer 6

1. somatic therapy
2. germ line therapy

Question 7

somatic therapy

Answer 7

• altering alleles in body cells
• doesnt affect the sex cells.

Question 8

germ line therapy

Answer 8

altering allele in sex cells
- every cell of any offspring produced will be affected by gene therapy and wont suffer from the disease.

Question 9

dna hybridisation-

Answer 9

• sample of dna is digested into fragments using restriction enzyme and separated using electrophoresis
• separated dna fragments then transferred into a nylon membrane and is incubated with fluorescently labelled dna probe
• allele is present, dna probe will hybridise to it
• membrane then exposed to uv light, if gene is present then there will be a fluorescent band.

Question 10

screening lots of genes at same time using dna micro array

Answer 10

• dna micro array is a glass slide with microscopic spots of different dna probes attatched in a row
• sample of fluorescently labelled human dna is washed over the probe
• if labelled human dna sequences contains any matching sequence to the probe, it will attach.
• array is washed to remove any dna thats nit attatched
• ## any spot that fluorescents means that persons dna contains the specific allele

Question 11

genetic counselling

Answer 11

• genetic counselling is advising patients and relatives about hthe risk of genetic disorders.
• treatment options can also be explained.