Chromosomes carry genes responsible for all physical and mental features of an organism. The human genome has a total of 46 chromosomes in pairs. Twenty-two sets of chromosomes are autosomes, while the remaining two are sex chromosomes. The sex chromosomes are responsible for determining the sex or gender of the offspring. Females have XX sex chromosomes, whereas males have XY chromosomes. A distinct difference between the X and Y chromosome is that one of them decides if the child will be a female and the other accounts for a male child. Here’s everything you need to know about sex chromosomes.
Comparison Table
| Characteristics | X Chromosome | Y Chromosome |
| Presence | Men & Women | Men |
| Sex Representation | XX means female | XY means male |
| Appearance | Looks like an X | Looks like Y |
| Genome Representation | 5% | 2% |
| Size | 5x larger | Smaller |
| Centromere | Metacentric | Acrocentric |
| Genes | 1000 | 70 |
| DNA Bases | 155 million | 95 million |
| Euchromatin | More | Less |
| Heterochromatin | Less | More |
| Inheritance | Crisscross | Straight |
| SYR Gene | Absent | Present |
What are Sex Chromosomes?
Sex chromosomes determine the sex or gender of the baby. When chromosomes are passed down from the parent to the daughter cells, each receives an equal number of chromosomes normally. Besides the autosomal chromosomes, they get one chromosome from each parent. Human females have two X chromosomes, one of which is active. Alternatively, males have one X and one Y chromosome. Both of them are active.
The chromosomes have two chromatids joined together at the centromere. They consist of two arms; the p arm and the q arm. One-half of the male gametes (sperms) have an x chromosome during division, while the other half has a y chromosome. The gender of the baby depends on the sperm that fertilizes the egg.
What is X Chromosome?
The X chromosome is one of the two sex chromosomes in humans. It comes from the female parent during cell division via mitosis and meiosis. The X-chromosome is called so because of its X shape. It is larger than the Y chromosome and contains unique genes. The X chromosome had over 155 million DNA base pairs and almost 900 genes responsible for several body functions.
These collectively depicts 5% of the total DNA in a female. As females contain both X chromosomes and men contain one X and one Y, all humans have at least one X chromosome in their genome. Female offspring get one X from their mother and the other from the father. On the contrary, men obtain the X chromosome from their mothers only.
The X-chromosome is inactivated during early embryonic development. This is known as X-inactivation or lyonization. Either of the two X chromosomes (from the father or the mother) may be inactivated. Besides unique characteristics, the X chromosome also carries various diseases known as X-linked diseases. Women carry two X chromosomes and are more susceptible to these disorders.
What is Y Chromosome?
The chromosome is the other sex chromosome besides the X chromosome. It is only present in males. The y chromosome contains 70 genes only. It is smaller than the X chromosome and has 59 million DNA base pairs. Y-chromosome exhibits 2% of the total genotype, where 7 to 200 genes produce proteins that are involved in male sex determination, thus defining the phenotype. The main difference between the X and Y chromosome is the SYR gene. The SYR gene on the chromosome develops the fetus into a male. Other genes determine fertility and secondary sex characteristics.
Like X-linked diseases, some conditions are Y-linked. One such example is Hypertrichosis of the ears. It is a condition in which hair grows on the outside rim of the ear. As only men have a Y-chromosome, these disorders are present in only males.
Similarities Between X and Y Chromosomes
- X and Y chromosomes are sex chromosomes.
- Both contain millions of genes.
- They comprise the p and q arms joined together at the centromere.
Difference Between X and Y Chromosomes
Definition
X Chromosome
The X chromosome is one of the sex chromosomes. One X chromosome is present in men and women.
Y Chromosome
Y chromosomes are the second type of sex chromosome. They determine the male sex characteristics.
Appearance
X Chromosome
The X chromosome looks like the alphabet X.
Y Chromosome
On the other hand, the Y chromosome arms are arranged in a way that gives the appearance of the Y alphabet.
Present in
X Chromosome
One X chromosome is present in both men and women. Females have two X chromosomes.
Y Chromosome
Whereas the Y chromosome is only found in men. They also have one X chromosome.
Representation
X Chromosome
X chromosomes represent 5% of the total genes in females.
Y Chromosome
Contrarily, Y chromosomes represent 2% of the total human genome in males.
Size
X Chromosome
The X chromosome is five times bigger in size than the Y chromosome.
Y Chromosome
Yet, the Y chromosome is smaller in size.
Structure
X Chromosome
The X chromosome is composed of two arms (p and q) joined together at the centromere. The centromere is present in the center of the chromosome and is called the metacentric.
Y Chromosome
At the same time, the Y chromosome has its centromere at one end, giving it a Y shape. This kind of chromosome is known as acrocentric.
Genes
X Chromosome
The X chromosome contains around 1000 unique genes that account for various features.
Y Chromosome
Alternatively, the Y chromosome has around 70 genes present on it.
DNA Bases
X Chromosome
The X chromosome has over 155 million DNA base pairs containing protein encodes for various activities.
Y Chromosome
However, the Y chromosome has 95 million protein-encoded base pairs.
Euchromatin and Heterochromatin
X Chromosome
The amount of heterochromatin and euchromatin is one of the most distinct differences between the X and Y chromosomes. X chromosomes contain a larger amount of euchromatin and a smaller amount of heterochromatin.
Y Chromosome
On the contrary, Y chromosomes have lesser euchromatin and more heterochromatin.
Inheritance Pattern
X Chromosome
X chromosomes show a zigzag or crisscross inheritance pattern.
Y Chromosome
But, Y chromosomes exhibit a straight inheritance pattern.
SYR Gene
X Chromosome
The SYR gene is not present on the X chromosome.
Y Chromosome
Although the Y chromosome contains the SYR gene that gives the male sex to the fetus.
The Bottom Line
X chromosome and Y chromosomes are the two types of sex chromosomes. They are essential for the determination of the sex of the offspring. The ability of the Y chromosome to give male sex to the fetus serves as a crucial difference between the two. Females contain two X chromosomes, whereas males have one X and one Y chromosome. X chromosomes contain more genes and are larger than Y chromosomes. They also account for specific X-linked and Y-linked traits and diseases in each gender.
FAQs
Does the Y chromosome mean boy or girl?
The Y chromosome is present in males with one X chromosome. At the same time, females have two X chromosomes. So, the Y chromosome is only present in males.
How to check the Y chromosome in sperm?
You can conduct genetic testing to see if your Y chromosome has all the essential elements to make sperm. Sometimes, the chromosome is not capable of making sperm due to genetic mutations.
How to increase Y chromosomes?
Though there is no scientific evidence of increasing Y chromosomes by yourself, chances may increase with alkaline foods. Many people intake fresh fruits and vegetables like potassium, avocados, and nuts to increase the Y chromosome. While eating fruits and vegetables is healthy, they are not very likely to increase Y chromosomes.
Anna has completed her degree in Pharmacy from the University of Hawaii. She is serving as a research assistant in a pharmaceutical company. She had a great interest in writing blogs, traveling to different parts of the US, and trying delicious recipes in her spare time.