Question

What is the difference between chromosome and chromatid?

When do we have to use these two terms? Give the explanation with diagrams.

Answer 1

Chromosome vs. chromatid:

Chromosome and Chromatid are terms in DNA study that are often confused in meaning due to its similarity in spelling. These two are closely related to each other and is part of the DNA structure. DNA or Deoxyribonucleic acid contains the genetic information in all living organism.

Chromosome:

Chromosomes are the thread-like form in DNA molecules in the nucleus of every cell in our body. In a human cell, there are 46 individual chromosomes and/or 23 chromosomes if in pairs. The pairing of the 46 chromosomes happened during the process of meiosis and mitosis. According to the German biologist, Theodor Heinrich Boveri, chromosomes are vectors of heredity which he found out during his extensive study and experiments.

Chromatid:

Chromatid is one out of the two similar copies of DNA that makes up a single chromosome. It should follow also that in a pair of chromosomes, there are two chromatids consisting it which are united by a centromere. During cell division (meiosis and mitosis), they are separated from each other and now called Sister chromatids which are identical to each other.

Difference between Chromosome and Chromatid:

Though these terms are closely related and very confusing to each other, there are still a lot of things that differs each one of them. A long and continuous strand of DNA is what Chromosomes are but when two chromatids are united together with a centromere, it produces one chromosome. Chromosomes, as mentioned above, are vectors of heredity or the ones that carries the genes of one organism to the other like the physical appearance and different characteristics while Chromatids are the ones who made possible the replication of these cells.
These DNA terms are really confusing if not studied deeply due to the fact that they are interconnected with other. To put it in a picture wherein every one can understand, chromosomes when viewed in a microscope is like an X shape. Divide the X by half and it would result into > and <. A single > or < is what you call a chromatid. The center point of contact is the centromere and the whole X is the chromosome.