DLA 18

Question 1

how can the size of the triplet repeat be measured

Answer 1

1. can measure by gel electrophoresis
2. column chromatography
3. southern blot

Question 2

What is G-band genetic testing good for?

Answer 2

looking at whole chromosome changes

very large deletions, duplication’s, and rearrangements

Question 3

how to prepare G-banding karyotype analysis or for FISH?

Answer 3

1. isolation of cells from peripheral blood sample
2. culture cells in the presence of phytohemagglutinin to stimulate cell division
3. arrest the cells at the metaphase phase of mitosis with colchicine
4. cells are swelled in a hypotonic solution and burst onto a microscope slide
5. chromosomes are fixed and prepared for staining and visualization

Question 4

what are the cons of G-banding?

Answer 4

1. low resolution
2. can always, for sure, determine if their is a problem
3. only large changes can be identified

Question 5

What are the benefits of FISH?

Answer 5

it has a better resolution compared to G-banding

they do not have to be in the metaphase stage

Question 6

what are the two general types of FISH?

Answer 6

1. chromosome specific (FISH)- used for a specific locus

2. chromosome painting (SKY)- whole genome- each chromosome is a different color

Question 7

What are the cons of FISH

Answer 7

must know what you are looking for

does not detect deletions (sky fish)

Question 8

What is microarray comparative genomic hybridization (array CGH)

Answer 8

a molecular cytogenetic technique that allows detection of DNA sequence copy number changes throughout the genome in a single hybridization

Question 9

How does array CGH show mutation?

Answer 9

will glow green if their is a gain in genomic DNA copies

will glow red if loss in genomic DNA copies

yellow = normal

Question 10

what is not shown in array CGH?

Answer 10

balanced translocations

triplet repeat expansions

SNPs

Question 11

what techniques show balanced translocations?

Answer 11

both forms of FISH

Question 12

cons of CGH array?

Answer 12

what is normal?

is the variation significant?

does not have a high dynamic range

Question 13

What is SNP array?

Answer 13

This analysis involves labeling genomic DNA fragments and allowing them to hybridize to DNA spots

each spot represents various alleles of a gene

Question 14

What does a + single on a SNP represent?

Answer 14

The presents of a particular SNP within the genome of that particular individual

2 = hetero
1= homo
(get genetic map quickly)

Question 15

What is the expression array? (cDNA microarray)

Answer 15

1. can be used to identify genes that are expressed

2. compare gene expression between cells

Question 16

How is a cDNA microarray done?

Answer 16

1. isolation of two tissues
2. isolation of RNA
3. production of labeled cDNA
4. competition for hybridization of labeled cDNA to microarray
5. visualization to compare

Question 17

how to read a cDNA microarray?

Answer 17

Red = more cDNA (diseased)

green = More cDNA (normal)

yellow = equal