genetic screening and counselling

Question 1

what is the role / purpose of a dna probe

Answer 1

to locate specific alleles of genes

Question 2

why are dna probes used

Answer 2

to identify if persons dna contains a mutated allele that can cause gentic disorder

Question 3

what are dna probes

Answer 3

short strands of dna that have specific base sequence that is complementory to traget allele

Question 4

how cand dna probe be identified

Answer 4

has a label attached wich is radioacitve

Question 5

describe the process of locating mutated allele using dna probe

Answer 5

first a sample of dna is digested into fragments using restriction endocnuclease and seperated using electroporesis

dna fragments transffered to anylon memebrane

incubated with fluorescent labelled dna probe

if allele is present dna probe will hydrolise (bind) to it

nylon membrane then exposed to uv light and if gene is present their will be a florescent band

Question 6

how is the sample of dna being tested prepared

Answer 6

digested into fragments using restriction endonuclease and then seperated into electrophoresis, before being transfered to nylon memebrane

Question 7

if allele is present what result occours

Answer 7

flouresant band

Question 8

what is anouther use of probes

Answer 8

detect lots of genes at the same time

Question 9

what is the process of detecting lots of genes at a time using dna probe known as

Answer 9

dna microarray

Question 10

what is a dna microarray

Answer 10

a glass slide with small spots of different dna probes attached in rows

Question 11

describe the processes of dna microarray

Answer 11

dna microarray is a glass slide with microscopic spots of differeant dna probes

fluorescent labelled human dna washed over

fluorescent wash contains human dna and if any of the dna sequences matches probes they will stick

array washed to remove any dna that hasn’t stuck

array visulised under uv light

any fluorescent spots means dna contains specific allele

Question 12

how is a dna probe produced and how can multiple copies be produced

Answer 12

sequence allele that you want to screen. then use pcr to produce multiple complementory copies of part of allele

Question 13

what is genetic counsliing

Answer 13

advising parents and relatives about the risks of genetic disorders either in procreation or who is the carrier or the most effective treatment

Question 14

Q1. explain what a dna probe is

Answer 14

dna probe is a short strand of dna, with a specific base sequence complementory to that of target allele

Question 15

Q2.outline the process of genetic screening for a disease

Answer 15

a sample of dna is digested using restriction endonuclease and seperated using electrophoresis
thes eperated dna fragments transferred to nylon mem and incubated with florescent dna probes
if complementory dna probes will hybridise to dna fragments greating a fluoresent strip

Question 16

Q3.Genetic screening shows that a
person has one mutant allele of
the tumour suppressor gene.
A. Describe the role of the
tumour suppressor gene.

Answer 16

it supresses the rapid division of an infected or begnihn cell.

Question 17

B. Suggest how the person
might use the information
revealed by genetic
screening.

Answer 17

the individual with the mutation may have not known about the mutated gene and so with this knowladge may seek treatment ask they ay be at a higher risk of cancer