Question

Which of the following is incorrectly paired?
a. SRY gene-X chromosome
b. 2n-2- Nullisomic
c. Nucleoid Prokaryotic
d. Polytene chromosome-Drosophila
e. Trisomy - Down's syndrome

Answer 1

Hint: Chromosomal abnormalities are of two types mainly they are numerical and structural, in the case of numerical it is due to the presence of one extra or one less chromosome than actual, and structural abnormalities are due to any alter in the shape and structure.

Complete answer:
- Chromosomal abnormalities mainly occur during the cell division, cell division is of two types, they are mitosis and meiosis.
- In the case of mitosis, the result is always the formation of two cells which are diploid in nature, this mitosis occurs in all over the body, except in the reproductive organs.
- While meiosis results in the formation of four haploid cells, where the chromosomes are half than the parent, and occurs majorly in reproductive parts.

When coming to given options first one is
> SRY gene and the full form is the sex determining region of Y, in humans it determines the male characters and it is discovered in the year 1990, SRY gene is present on the Y chromosome in the humans, and its presence makes the embryo to develop into male.

> Nullisomy Is the condition where the homologous pair of chromosomes are missing and it leads to 2n-2 genotypes.

> Nucleoid is the genetic material that is commonly found in the cells of prokaryotes.

> Polytene chromosome is the one which is larger in size than regular ones, which develops from normal chromosomes found in the salivary glands of Drosophila.

> Trisomy is the condition that occurs due to the presence of one extra chromosome on the 21st one which results in Down's syndrome.

Hence, The correct answer is option (A).

Note: One should have a proper idea about genes, and the DNA as there forming proteins, so any mutation happens results in the abnormal formation of proteins and results in medical conditions, these all happen with any defect or any change in the numerical or any other defects.