Genetics

Question 1

Describe the short and long arms of the chromosome

Answer 1

Centromere is the centre, telomere is at the ends of the chromosome and the short arm is P and long arm is Q

Question 2

How many times is the resolution better in array CGH sompared to karyotyping?

Answer 2

x100 times , detects duplications and deletions >50,000 bases

Question 3

What are 5 structural abnormalities of chromosomes?

Answer 3

Look at notebook

Question 4

What are some limitations of array CGH?

Answer 4

Cannot detect balanced chromosomal rearrangements and does not distinguish unbalanced chromosomal rearrangements caused by mechanisms such as trisomy 21 caused by robertsonian translocation

Question 5

What is array CGH?

Answer 5

Also known as microarray- first line instead of karyotyping. Patient (green) and contral DNA (red) are compared. Fragments of DNA which bind to the genome are suspended on a slide and immersed in a solution that has equal amounts of patient green DNA and control red DNA. If it fluroscenes red this is due to an excess of control DNA (i.e. patient deletion) and if it is green this is excess of patient DNA (i.e. patient duplication)

Question 6

What is karyotyping?

Answer 6

Diving cells are looked at under the microscope, the cell is stained and chromosome examined

Question 7

What might karyotyping miss?

Answer 7

Miss any changes smaller than 5-10 megabases which is 5-10 million bases so unsuitable for detecting microdeletions and duplications