A gamete and a zygote are two distinct stages in the process of sexual reproduction in organisms:
1. Gamete:
Gametes are specialized reproductive cells that are produced by sexually reproducing organisms. They are haploid cells, meaning they contain only half the usual number of chromosomes found in somatic cells (body cells). In humans, gametes are produced through a process called meiosis, which reduces the chromosome number from diploid (46 chromosomes in humans) to haploid (23 chromosomes in humans).
In males, the gamete is called sperm, and it is produced in the testes. Sperm is small and highly motile, allowing it to move towards and fertilize the female gamete.
In females, the gamete is called an egg or ovum, and it is produced in the ovaries. The egg is relatively large and contains nutrients to support early development after fertilization.
2. Zygote:
When a sperm cell (gamete) from a male fuses with an egg cell (gamete) from a female during fertilization, they form a zygote. The zygote is the first diploid cell of a new organism, containing the complete set of chromosomes from both parents (the combined number of chromosomes). In humans, the zygote has 46 chromosomes (23 from the sperm and 23 from the egg).
The zygote represents the starting point of development for a new individual. It undergoes cell division and differentiation, eventually developing into an embryo, and later a fetus, during pregnancy.
In summary, the main difference between a gamete and a zygote is that a gamete is a haploid reproductive cell with half the chromosome number of somatic cells, while a zygote is the diploid cell formed by the fusion of two gametes during fertilization, containing the complete set of chromosomes for a new organism.