Chromosome vs Chromatid: Difference and Comparison

Scientific words can be confusing to comprehend because of their diction similarities. Chromosomes and Chromatids are one such pair of words.

Although the two words are associated with one another, it is scientifically inappropriate to use them interchangeably because they are considerably different.

Key Takeaways

  1. A chromosome is a thread-like structure of DNA that carries genetic information. A chromatid is one of two identical copies of a replicated chromosome that are joined at the centromere.
  2. Chromosomes are present in pairs in most cells, while chromatids are only present during cell division.
  3. Chromosomes are visible during cell division, while chromatids cannot be seen individually without specialized techniques.

Chromosome vs Chromatid

Chromosome is hereditary substance which transmits genetic information from cell to cell during cell division. Chromatid is a substance which makes a chromosome. A chromatid is one half of a chromosome. Two sister chromatids joined in the center with a centriole make a chromosome. Chromatids double during cell division.

Chromosome vs Chromatid

Chromosome is derived from the Greek word Chroma and Soma, which means colour and body, respectively. By definition, a chromosome is a genetic material responsible for all the features and characteristics of organisms.

In human beings, chromosomes are divided into autosomes and allosomes. Autosomes are the body’s chromosomes.

Chromosomes are responsible for genetic diversity in sexually reproducing organisms like humans. The term chromatid was given by McClung and is derived from the Greek word chroma, which means colour.

Chromatid refers to the identical copies of the DNA that make up a chromosome. There are two types of chromatids: sister chromatids and non-sister chromatids.

Moreover, chromatids may be homozygous or heterozygous. Chromatids are unable to transcribe proteins.

But they are crucial during the meiosis of cell division. 

Comparison Table

Parameters of ComparisonChromosome Chromatid
DefinitionChromosome refers to a ribbon-like structure found in the nuclear region or nucleus of the cytoplasm. Chromatid refers to an identical half of a duplicated chromosome. 
StructureThe structural composition of chromosomes is thin and ribbon-like.The structural composition of chromatids is fibrous, long, and thin.
DNAIn a chromosome, the DNA molecules are tightly packed.In a chromatid, the DNA molecule is free and unwounded. 
ReplicationChromosomes are capable of replicating or duplicating themselves.Chromatids are unable to duplicate themselves. 
Present Chromosomes are present throughout the lifetime of all cells. Chromatids come into existence during the interphase. Additionally, they exist only till the metaphase of cell division. 

What is Chromosome?

Chromosome refers to a ribbon-like structure found in the nucleus of the cytoplasm. The composition of a chromosome consists of proteins and a single molecule of Deoxyribonucleic Acid (DNA).

Only during the metaphase of the cell cycle can one observe chromosomes under a light microscope. There are two categories of chromosomes in humans: autosomes and allosomes.

The body chromosomes are known as autosomes. On the other hand, the sex chromosomes are allosomes.

Additionally, there are 23 pairs of chromosomes in the human body. While 22 pairs of chromosomes are autosomes, there is one pair of allsomes.

In total, there are 46 chromosomes in the human body. The structure of the chromosome varies according to the phase of the cell cycle.

Prokaryotic organisms have a single circular chromosome due to the absence of a specified nuclear region. In contrast, in eukaryotic organisms like humans, chromosomes are packed into a condensed structure to fit in the nucleus. 

In sexually reproducing organisms like humans, chromosomes play a vital role in ensuring genetic diversity. Chromosomes are the carriers of genetic materials that are essential for a number of functions, such as division and reproduction and protein generation.

Chromosomal deformities may cause various chromosomal disorders that are detrimental to an organism. 

chromosome

What is Chromatid?

Chromatid refers to an identical half of a duplicated chromosome. The duplication of chromosomes results in the formation of two identical halves; each one of these halves is a chromatid.

As compared to chromosomes, chromatids are less condensed because chromatids form when chromosomes are uncoiled. There are two types of chromatids: sister chromatids and non-sister chromatids.

Sister chromatids refer to the chromatids from the same chromosomes. On the other hand, non-sister chromatids refer to chromatids from two different chromosomes.

Additionally, non-sister chromatids connect via chiasmata for the exchange of genetic material. Chromatids are mostly homozygous because they are identical.

However, they may be heterozygous sometimes when mutations cause a change in either one or both chromatids. More importantly, chromatids are temporary structures that assist in the process of chromosome duplication and separation. 

Chromatids are unable to transcribe proteins. But they are crucial during the meiosis of cell division.

As a cell divides itself, chromatids separate themselves to form individual chromosomes. This event ensures the genetic diversity within the species as well as genetic variability.

Thus, chromatids are less condensed structures crucial for sexual reproduction. 

chromatid

Main Differences Between Chromosome and Chromatid 

  1. Chromosome refers to a thread-like structure in the cytoplasm’s nuclear region or nucleus. In contrast, chromatid refers to an identical half of a duplicated chromosome.
  2. Chromosomes are present throughout the lifetime of all cells. On the other hand, chromatids come into existence during the interphase. Additionally, they exist only till the metaphase of cell division. 
  3. While chromosomes have a thin ribbon-like structure, chromatids have a long and lean fibrous structure. 
  4. Chromosomes are capable of replicating or duplicating themselves. On the other hand, chromatids are unable to replicate themselves. 
  5. In a chromosome, the DNA molecules are tightly packed. In contrast, the DNA molecule is free and unwounded in a chromatid. 
Difference Between Chromosome and Chromatid
References
  1. https://www.osti.gov/etdeweb/biblio/6937261 
  2. http://symposium.cshlp.org/content/16/13.short 

Last Updated : 11 June, 2023

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17 thoughts on “Chromosome vs Chromatid: Difference and Comparison”

  1. This is an extensive article, but it is not very reader-friendly. I think it could benefit from a more concise and clear format.

    Reply
  2. This article offers a great and very detailed explanation of the differences between chromosomes and chromatids. Thank you for sharing!

    Reply
  3. While the article is quite enlightening, it could be made more engaging through the use of real-life examples to explain certain concepts.

    Reply
  4. I found it fascinating to learn the origin of the terms chromosome and chromatid. It adds an interesting dimension to the scientific definitions.

    Reply
  5. I was looking for clarity on this subject, and I must say, this article more than delivered. It’s an excellent resource.

    Reply

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