Describe structure of a chromosome.

Chromosomes are thread-like structures usually present in the nucleus that become visible only during cell divisions. Chromosomes contain information for inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules. Chromosomes are composed of DNA and protein. DNA molecules contain the information necessary for constructing and organising cells. Functional segments of DNA are called genes.

A chromosome consists of two identical and spirally coiled threads called sister chromatids. They are joined at a constriction called centromere.