gene probes and medical diagnosis

Question 1

DNA probes

Answer 1

1. use to locate specific alleles of genes - see if DNA contains mutated allele that causes genetic disorder
2. DNA probes are short strands of DNA. specific base sequence thats complimentary to bases of target allele
3. DNA probe will bind (hybridise) to target allele if present
4. DNA probe has label attached so it can be detected e.g. radioactive (use xray film) or fluorescent (use UV light)

Question 2

how to look for alleles using DNA probes

Answer 2

1. digest sample of DNA into fragments using restriction endonuclease.
2. separate using electrophoresis
3. transfer to nylon membrane and incubate with fluorescently labelled DNA probe
4. if allele present DNA probe hybridise/bind to it
5. membrane is exposed to UV light and if allele present - fluorescent band

Question 3

how to look for alleles using DNA probes and DNA microarray

Answer 3

1. DNA microarray glass slide with microscopic cpots of different DNA probes attached to it in rows
2. sample of fluorescently labelled human DNA washed over it
3. labelled DNA contains DNA sequence that match any of probes will stick to array
4. array washed to remove any DNA that hasnt stuck
5. visualised under UV light - any labelled DNA attached to a probe will show up = persons DNA contains specific allele

Question 4

to produce DNA probe first need to

Answer 4

sequence allele you want to screen for

then use PCR to produce multiple complimentary copies of that part of the allele

Question 5

uses of screening using DNA probes

Answer 5

1. help identify inherited conditions
2. help identify how a patient will respond to specific drugs
3. help identify health risks

Question 6

genetic counselling

Answer 6

1. advising patient and relatives about risks of genetic disorders
2. advising patient about screening and explaining results of screening
3. can help identify if someone is a carrier of a muatated allele and the type of mutate allele theyre carrying -> most effective treatment
4. screening positive - patient advised on options of prevention or treatment available

Question 7

personalised medcine

Answer 7

genes determine how body responds to certain drugs
different people respond to same drug in different ways
certain drugs more effective for some people than others
personalised medcine is tailored to an individuals DNA - if doctors have your genetic info can use it to predict how you will respond. only prescribe most effective drug