What is the Difference Between Male and Female Karyotypes

The main difference between male and female karyotypes is that the male karyotype consists of one X and one Y chromosome as their sex chromosome pair whereas the female karyotype consists of two X chromosomes as their sex chromosome pair. However, all autosomal chromosome pairs are similar in number and appearance in both male and female karyotypes.

Male and female karyotypes are the two complete sets of chromosomes of the two genders of humans, describing both the number and the appearance of the chromosomes in the nucleus of somatic cells of the body. Generally, humans have 22 pairs of autosomal chromosomes and a pair of sex chromosomes.

Key Areas Covered

1. What is the Male Karyotype
     – Definition, Sex Chromosomes, Importance
2. What is the Female Karyotype
     – Definition, Sex Chromosomes, Importance
3. What are the Similarities Between Male and Female Karyotypes
     – Outline of Common Features
4. What is the Difference Between Male and Female Karyotypes
     – Comparison of Key Differences

Key Terms

Autosomes, Female Karyotype, Male Karyotype, Sex Chromosomes, X Chromosome, Y Chromosome

What is the Male Karyotype

Male karyotype is basically the appearance of the complete set of chromosomes in a somatic cell of a male. It allows the determination of the number of chromosomes and their physical characteristics. Generally, all somatic cells of the body of a human contain 46 chromosomes, which can be classified into 22 pairs of autosomes and a pair of allosomes or sex chromosomes. The autosomal pairs of both males as females are similar. However, the main characteristic feature of a male karyotype is the presence of an X chromosome and a Y chromosome in the sex chromosome pair.

Figure 1: Male and female Karyotypes of Humans

In other words, the Y chromosome is one of the two sex-determining chromosomes in humans as well as many other species. It only passes from father to the son. The size of the Y chromosome in humans is around 59 million base pairs. Moreover, around 200 Y-linked genes have been identified so far, including the SRY gene responsible for the development of the testis. Under normal conditions, the expression of all of these genes occurs hemizygously. Furthermore, the Y chromosome is one of the fastest evolving parts of the human genome.

What is the Female Karyotype

Female karyotype is the appearance of the complete set of chromosomes in a somatic cell of a female. The main characteristic feature of a female karyotype is the presence of a pair of X chromosomes as allosomes. Therefore, X chromosome is the other sex-determining chromosome in humans. The X chromosome found in males has a maternal origin. However, one of the X chromosomes in the karyotype has maternal origin while the second X chromosome has the paternal origin. Moreover, an X chromosome contains more than 153 million base pairs. It also contains around 200 genes. Especially, 200-300 genes on the X chromosome are unique to the sex. The rest of the genes are expressed similarly in both males and females.

Figure 2: Klinefelter Syndrome (XXY)

Furthermore, the size of the chromosomes is another characteristic feature that can be used in identifying the between male and female karyotypes. Some other differences between male and female karyotypes include the number of genes and abnormal chromosomal pairing.

Similarities Between Male and Female Karyotypes

• Male and female karyotypes are two types of complete sets of chromosomes of the two genders of humans.
• The two types of chromosomes in both types of karyotypes are the autosomal and sex chromosomes. Generally, both male and female karyotypes contain autosomal chromosome pairs similar in both number and appearance.
• Both of them allow the determination of the number and appearance of each chromosome in the nucleus of a somatic cell.
• Also, both types of karyotypes allow the identification of the length of chromosomes, the position of the centromere, and the banding pattern. Also, they allow the determination of the physical characteristics of chromosomes.
• Besides, both are important in the identification of chromosome abnormalities.

Difference Between Male and Female Karyotypes

Definition

The male karyotype refers to the appearance of the complete set of chromosomes in a somatic cell of a male while the female karyotype refers to the appearance of the complete set of chromosomes in a somatic cell of a female.

Sex Chromosomes

More importantly, the male karyotype contains one X and one Y chromosome as their sex chromosomes while the female karyotype contains two X chromosomes as their sex chromosomes. Thus, this is the main difference between male and female karyotypes.

Denotation

Another difference between male and female karyotypes is that the male karyotype is denoted as 46:XY while the female karyotype is denoted as 46:XX.

Working Genes

Generally, the Y chromosome of males contains less than 200 working genes while the X chromosome of females contains more than 1000 working genes.

Sex Abnormalities

Klinefelter syndrome (XXY) and XYY syndrome are examples of sex abnormalities found in male karyotypes while Turner syndrome (X0) and triple X syndrome are the examples of sex abnormalities found in female karyotypes. Hence, this is another difference between male and female karyotypes.

Conclusion

The male karyotype is the number and the appearance of the complete chromosome set of a male. It contains 22 pairs of autosomal chromosomes and a pair of sex chromosomes including one X and one Y chromosome. In comparison, the female karyotype is the number and appearance of the complete set of chromosomes of a somatic cell of a female. Though it contains a similar number of autosomal chromosome pairs with a similar appearance, the female karyotype contains a pair of X chromosomes as sex chromosomes. Therefore, the main difference between male and female karyotypes is the difference in the sex chromosomes.

References:

1. “Chromosome Analysis (Karyotyping).” Lab Tests Online – Explaining Pathology, Available Here.

Image Courtesy:

1. “Human karyotype” By Mikael Häggström (Public Domain) via Commons Wikimedia  
2. “Human chromosomesXXY01” By User:Nami-ja – Own work (Public Domain) via Commons Wikimedia