Chromosomal abnormalities

Question 1

What is Euchromatin?

Answer 1

Lightly packed chromatin often under active transcription

Question 2

What is Heterochromatin?

Answer 2

Tightly packed chromatin

Question 3

What is Polyploidy?

Answer 3

An abnormal number of chromosomes that is a multiple of the haploid number

Question 4

What is Aneuploidy?

Answer 4

An abnormal number of chromosomes that is not a multiple of the haploid number

Question 5

What is Monosomy?

Answer 5

Loss of one chromosome

Question 6

What is Trisomy?

Answer 6

The gain of one chromosome

Question 7

What are the types of structural chromosome abnormalities?

Answer 7

Balanced (No change to genetic information with change)

Unbalanced (Change causes extra or missing genetic information)

Question 8

What are the chromosome abnormalities involving one chromosome?

Answer 8

Deletion
Duplication
Inversion (Change in arrangement)
Ring chromosome (Loss of telomeres)
Isochromosome (Creates 2 non identical chromosomes - one has 2 short arms, other has 2 long arms)

Question 9

What are the chromosome abnormalities involving two chromosomes?

Answer 9

Inversion
Reciprocal translation (Change of genetic material between 2 non homologous)
Robertsonian translocation (Rearrangement of genetic material between 2 chromosomes. Combines to form one super chromosome)

Question 10

What is Karyotyping?

Answer 10

Placing chromosome pictures into a systemically organised set of metaphase chromosomes organised in pairs

Question 11

What is the Karyotype number of a cell?

Answer 11

Total number of chromosomes in the cell (followed by a comma) then the X then the Y

Question 12

What are the main reasons for referring patients for Karyotyping?

Answer 12

Congenital abnormalities - Prenatal screening

Acquired abnormalities - Leukaemia

Question 13

How can FISH detect chromosomal abnormalities?

Answer 13

The degree of sequence identity can be determined, and specific sequences (or genes) can be detected and located on a given chromosome