What are the differences between chromosomes and chromatids?

Basis of Differentiation 

Chromosome

Chromatid 

Definition 

A chromosome is a DNA molecule that has all or part of the genetic material of an organism.

A chromatid is one copy of a newly copied chromosome. It is still attached to the original chromosome by a single centromere. 

Content

A chromosome consists of a single, double-stranded DNA molecule.

A chromatid consists of two DNA strands joined together by their centromere.

Structure

Its structure is thin and ribbon-like.

Its structure is thin, long, and fibrous.

Condensation 

A chromosome is the most condensed form of DNA. DNA is condensed 10,000 times to form a chromosome. 

A chromatid is less condensed. It has an unraveled condensed structure of DNA. DNA is condensed 50 times to form a chromatid. 

Occurrence 

Chromosomes occur throughout the life cycle of cells. 

Chromatids are only created when the cell undergoes mitosis or meiosis.

Genetic material/ identical – non-identical 

Homologous chromosomes are not identical. They have different traits as one copy of the gene comes from each parent.

Homologous sister chromatids are identical. Each sister chromatid is an exact copy of the other. 

Stage of appearance

Chromosomes appear in M phase.

Chromatids appear in the interphase. 

Function 

Chromosomes carry and distribute the genetic material.

Chromatids are involved in metabolism and other cellular activities, allow cells to duplicate

Macromolecule Synthesis

DNA is not used.

DNA is used.