Cytogenetics

Question 1

What is cytogenetics?

Answer 1

Study of chromosomes and their abnormalities is called cytogenetics

Question 2

Classification of chromosomes based on centromere location

Answer 2

1. Metacentric : centromere is in the centre
2. Sub metacentric: centromere shifted towards the tip.
3. acrocentric: centromere is near the tip

Question 3

Euploid

Answer 3

Cell containing multiple of 23 chromosomes (haploid gametes and diploid cells)

Question 4

Triploidy

Answer 4

Total of 69 chromosomes in the nucleus and Tetraploidy is when total of 92 chromosomes in the nucleus

Question 5

Aneuploidy and types and causes

Answer 5

Cell containing one more or one less chromosome
1. Autosomal cell aneuploidies
a. monosomy: one less chromosome (only contain one copy instead two)
b. trisomy: contains three copies of chromosomes of chromosomes 21(dawn syndrome), 18 (edward syndrome), 13 (patau syndrome)

2. Sex chromosomes aneuploidies
   a. monosomy: Turner syndrome 45X
   b. trisomy: Klinefelter syndrome 47XXY

Common cause is nondisjunction and maternal age

Question 6

Translocation and types

Answer 6

A translocation is the interchange of genetic material between nonhomologous chromosomes

1. Reciprocal: two breaks on different chromosomes and exchange of genetic information. Carrier is with normal phenotype, but their offspring may have trisomy or monosomy.
2. Robertsonian: occurs mostly with acrocentric chromosomes when short end of chromosome is lost, and two long ends fuses at the centromere.