What is the Difference Between Karyotype and Karyogram

The main difference between karyotype and karyogram is that the karyotype is the number, size, and shape of chromosomes of a particular organism whereas the karyogram is a visual profile of stained chromosomes in a standard format. Furthermore, a karyotype describes the characteristics of chromosomes while a karyogram helps to visualize those characteristics. 

Karyotype and karyogram are two items which help to determine the chromosome complement of an individual. Moreover, they help to determine chromosome abnormalities. 

Key Areas Covered

1. What is a Karyotype
     – Definition, Features, Importance
2. What is a Karyogram
     – Definition, Features, Importance
3. What are the Similarities Between Karyotype and Karyogram
     – Outline of Common Features
4. What is the Difference Between Karyotype and Karyogram
     – Comparison of Key Differences

Key Terms 

Autosome, Chromosome Abnormalities, Chromosomes, Karyogram, Karyotype

What is a Karyotype 

A karyotype is the complete set of chromosomes of an individual. Generally, in humans, a diploid cell contains 23 pairs of chromosomes. Out of which, 22 pairs are autosomes, and the rest are sex chromosomes. Typically, there are two different sex chromosomes in humans: X chromosome and the Y chromosome. Of these, the male human karyotype contains one X and one Y chromosome, denoted as 46: XY. Meantime, the female karyotype contains two X chromosomes, denoted as 46: XX. 

Figure 1: Human Karyotype with Down Syndrome

Significantly, these chromosomes differ from each other by their size, centromere position, and banding pattern. Therefore, based on that, each chromosome pair has a standard number. Moreover, each chromosome has two arms separated by its centromere. Here, the shorter arm is the p arm, and the longer arm is the q arm. Besides, the largest chromosome pair in the human karyotype is chromosome 1. In contrast, the shortest is chromosome 22. 

What is a Karyogram 

A karyogram is the standard format of chromosomes produced by the rearrangement of the photomicrographs of chromosomes. Generally, during karyotyping, the standardized staining procedures reveal the characteristic structural features of chromosomes. For this, the cell cycle of cells of a particular tissue is arrested at the metaphase of the mitotic cell division. Then, these cells contain the most condensed form of chromosomes. Now, they can be stained with a dye called Giemsa. After that, visualized chromosomes can be arranged in an order based on the absolute and relative sizes, positions of chromosomes, degree of distribution of heterochromatic regions, etc.

Figure 2: A Karyogram with Down Syndrome

Concerning the significance of karyogram, one of the main importance of it is to identify the structural and numerical abnormalities in chromosomes. As an example, one of the aneuploid conditions, such as trisomy 21, leads to Down syndrome. Also, a careful analysis can reveal some of the subtle structural changes, including chromosomal deletions, duplications, translocations, inversions, etc.  

Similarities Between Karyotype and Karyogram 

• Karyotype and karyogram are two terms that determine the characteristics of chromosomes of an individual. 
• Moreover, they help to evaluate chromosomal abnormalities, which lead to genetic disorders. 

Difference Between Karyotype and Karyogram 

Definition 

Karyotype refers to the complete set of chromosomes of an individual, while karyogram refers to the visual profile of stained chromosomes in a standard format. Thus, this is the main difference between karyotype and karyogram.

Characteristics 

Also, another difference between karyotype and karyogram is that while karyotype describes the number and appearance of chromosomes and includes their length, banding pattern, and centromere position, karyogram contains chromosomes arranged in an appropriate order.   

Importance 

Moreover, karyotype helps to determine the chromosome complement of an organism while a karyogram helps to identify chromosomal aberrations. 

Conclusion 

Basically, a karyotype is a number and appearance of chromosome set of an organism. On the contrary, karyogram is a visual interpretation of chromosomes with a standard arrangement. However, both karyotype and karyogram help to determine the chromosome complement of an organism and its abnormalities of chromosomes. Hence, the main difference between karyotype and karyogram is their significance.   

References:

1. O’Connor, C. (2008) Karyotyping for chromosomal abnormalities. Nature Education 1(1):27, Available Here.

Image Courtesy:

1. “Human karyotype (263 16) Karyotype Human 47, XY, +21 (Down syndrome)” By Doc. RNDr. Josef Reischig, CSc. – Author’s archive (CC BY-SA 3.0) via Commons Wikimedia   
2. “21 trisomy – Down syndrome” By U.S. Department of Energy Human Genome Program. (Public Domain) via Commons Wikimedia