How Sex Is Determined in Human? Chromosomal Basis of Sex Determination
What is Sex Determination?
Sex determination is the biological process by which the sex of an individual is established based on the combination of sex chromosomes inherited from the parents.
In humans, sex is determined by the combination of X and Y chromosomes present in the fertilized egg.
Human Chromosomes
Human beings possess 46 chromosomes arranged in 23 pairs inside the nucleus of each body cell.
These chromosomes are classified into:
- Autosomal Chromosomes
- Sex Chromosomes
Autosomal Chromosomes
Autosomes control most body characteristics such as height, skin color, facial features and other non-sexual traits.
Humans possess 22 pairs of autosomes.
Sex Chromosomes
Sex chromosomes determine the biological sex of an individual.
| Sex | Chromosomes |
|---|---|
| Female | XX |
| Male | XY |
Role of Gametes in Sex Determination
During reproduction, both male and female produce gametes through meiosis.
Male Gametes (Sperm)
- Half carry X chromosome.
- Half carry Y chromosome.
Female Gametes (Ovum)
- All ova carry X chromosome.
Sex Determination During Fertilization
The sex of the baby depends on which type of sperm fertilizes the ovum.
| Sperm | Ovum | Result | Sex |
|---|---|---|---|
| X | X | XX | Female |
| Y | X | XY | Male |
Probability of Male and Female Child
Since sperm carrying X and Y chromosomes are produced in approximately equal numbers, there is an equal probability of producing a male or female child.
- 50% chance of Female (XX)
- 50% chance of Male (XY)
Amniocentesis
Amniocentesis is a prenatal diagnostic procedure in which a small sample of amniotic fluid is collected for genetic analysis.
It can detect chromosomal abnormalities and certain inherited disorders.
Frequently Asked Questions
How is sex determined in humans?
Sex is determined by the combination of X and Y chromosomes during fertilization.
Which parent determines the sex of the child?
The sperm from the father contributes either an X or Y chromosome and therefore determines the chromosomal sex.
What chromosomes are present in females?
Females possess XX chromosomes.
What chromosomes are present in males?
Males possess XY chromosomes.
What is the probability of having a boy or girl?
Both have approximately equal probability (50%).