Cytogenetics

Question 1

Cytogenetics

Answer 1

The study and analysation of chromosomes

Question 1

Human karyotype

Answer 1

During metaphase: Chromosomes are condensed on a metaphase plate and hence we stain specific regions within the chromosome

Question 2

Chromosome banding

Answer 2

Defined based on different types of staining

Question 3

G-banding

Answer 3

most common
uses giesma

Question 4

Q- banding

Answer 4

uses a fluorescent dye which stains AT rick DNA

Question 5

R- banding

Answer 5

stains GC rich DNA regions

Question 6

T banding

Answer 6

subset of R bands, concentrated at telomeres

Question 7

C banding

Answer 7

stains for constitutive heterochromatin

Question 8

What is the resolution of conventional cytogenetics?

Answer 8

5-10Mb

Question 9

Kinds of body tissues used for karyotype

Answer 9

bone marrow
blood
solid tissues
amniocentesis
chorionic villus sampling

Question 10

molecular cytogenetics

Answer 10

the study of chromosomes without using banding, but rather using DNA-based techniques for labelling and visualisation of the DNA and chromosome structure

Question 11

FISH fluorescent in-situ hybridisation

Answer 11

Label a specific region of a chromosome using a probe [a small piece of purifies DNA tagged with a fluorescent dye]

Question 12

Resolution of FISH

Answer 12

100-200kb

Question 13

How can we increase the resolution of FISH?

Answer 13

Using less compact DNA

Question 14

Chromosome painting

Answer 14

The usage and hybridisation of a series of DNA probes that match several regions of the same chromosome to obtain an entirely fluorescent chromosome

Question 15

Philadelphia Translocation

Answer 15

part of the chromosome 9 is translocated on chromosome 22: abl gene placed downstream of the bcr gene –> related to cancer

Question 16

Comparative Genomic Hybridisation

Answer 16

Used to understand whether we have a structural abnormality that can be insertions or deletions that are affecting the copy numbers of the genomic material we are analysing

Question 17

Discuss CGH

Answer 17

We label the DNA that we want to test with one fluorescent de and we label the controlled DNA. The mutated DNA and a control one are mixed together and are hybridised on a metaphase plate.

If the 2 signals are overlapping, then we have equimolar amounts. If we have only one fluorescent dye then we have either a loss or gain of DNA material

Question 18

Array CGH

Answer 18

Much higher resolution than CGH
not on a metaphase plate but on a chip where have spotted oligonucleotides each specific for the DNA

Question 19

What can and what cannot array CGH detect?

Answer 19

Inversions and translocations cannot be detected; duplications can be

Question 20

Using BAC in CGH

Answer 20

resolution 100kb

Question 21

Using cDNA in CGH

Answer 21

resolution 2kb

Question 22

Resolution of oligo arrays

Answer 22

0.06kb= 60bp