Question

How many chromosomes does a human sex cell have?

Answer 1

Hint: Chromosomes are thread-like structures made up of DNA and proteins and are present inside the- nucleus of a cell. They carry genetic information from one generation to another.

Complete answer:
Sex cells are the reproductive cells or the gametes of an organism. The human sex cells are formed through the process of meiosis or reductional division. They have a single set of chromosomes and are haploid in nature.

The genetic material of humans- DNA, is packed into thread-like structures called chromosomes. They are located inside the nucleus of cells and carry genetic information about the organisms. They also play an important role in heredity and variation, mutation, cell division, etc. DNA is a molecule that contains two polynucleotide chains that run anti-parallel to each other and contains the genetic code of an organism. A sequence of nucleotides on DNA forms a gene- the functional unit of heredity and inheritance. The negatively charged DNA coils around eight positively charged histone proteins to form a nucleosome. The strand of nucleosomes folds up to form chromatin fiber. Chromatin fibers are tightly packed to form chromosomes.
The number of chromosomes differs from one cell to another- and is determined by the ploidy level of that cell. The number of a complete set of chromosomes in the nucleus of a cell is called its ploidy. The human sex cells are haploid in nature, which means they have a single set of chromosomes. The chromosomes are not paired here and do not form a homologous structure.

In humans, gametes are formed during the course of sexual reproduction through the process of meiosis. The male gamete is called the sperm or the spermatozoa, and the female gamete is called the egg or the ova.

Both these gametes have 23 unpaired chromosomes in their nucleus. 22 chromosomes in these gametes are autosomes, while the last chromosome is the sex chromosome that determines the sex of an individual. The genetic constitution of a male gamete can be - 22+X or 22+Y. They are produced in the testis of the males. The genetic constitution of a female gamete is 22+X. They are matured in the ovary of females. These two gametes fuse during sexual reproduction to form the diploid zygote that develops further to form a diploid individual- 44+XX or 44+XY.
In Humans, the males have 44+XY chromosomes while the females have 44+XX chromosomes. The last pair of chromosomes are the sex chromosomes. Males have both X and Y chromosomes, while females have two X chromosomes.

Note: X and Y are the sex chromosomes that determine the sex of an individual. The X chromosome is longer than the Y chromosome and has more number of genes. Both these chromosomes- are inherited by the offspring from their parents.