Question

2. What is meant by 'chromosome'. Explain its types with diagrams​

Answer 1

Answer:

chromosome is an organized package of DNA found in nucleus of the cell different organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes--22 pairs of numbered chromosomes, called autosomes, and one pair of sex chromosomes, X and Y.

Answer 2

$\underline{\textsf{\textbf{Chromosome :}}}$

The network of nucleoprotein fibre in nucleus is called chromatin. These chromatin appears as structural chromosomes during different stages of cell division. Chromosomes are rod-shaped and thread-like condensed chromatin fibres which appear during karyokinesis.

each chromosomes have two halves or chromatids, which are attached to each other by centromere or primary constructions.

$\underline{\textsf{\textbf{Types of Chromosome :}}}$

On the basis of number of centromeres, chromosomes can be divided into 4 parts

• Acentric - No centromere

• Monocentric - Single centromere

• Dicentric - Two centromeres, forms due to translocation

• Polycentric - multiple centromeres, formed due to diffused condition.

On the basis of position of centromeres, chromosomes can be divided into 4 parts

• Sub- metacentric - submedially placed centromere

• Metacentric - centromere at the middle

• Acrocentric - subterminally placed centromere

• Telocentric - terminally placed centromere

On the basis of function of centromeres, chromosomes can be divided into 2 parts

• Autosomes - contain genes for somatic characters.

• Sex chromosomes - carriers of sex determining genes.