The sex cells are responsible for forming an embryo during sexual reproduction. This embryo will later develop into a new organism.
These cells are different for each of the two sexes. Sex cells are given different names for animal and plant species: oosphere and pollen in plants, and oocyte (also known as ovum) and sperm in animals.
Sex cells stick together during the reproductive process. As their DNA comes together, a new cell is formed that will reproduce and expand to form a new organism.
Main features
Sex cells differ from the rest of the cells of the organisms that produce them because they only have one chromosome.
That is, they only have one copy of the genetic information that they will pass on to the next generation.
When male and female sex cells come together, a recombination process of their DNA occurs.
The resulting cell, also known as a zygote, therefore has two chromosomes, with one half coming from each of its parents.
The process by which male and female sex cells join and recombine their DNA is known as fertilization.
Sex cells in animals
In animal species that reproduce sexually, sex cells or gametes are produced inside special organs. These organs are known as sex glands.
The sex glands of males are known as testes, and those of females as ovaries.
Both types of glands come into operation during the sexual maturity of the organism.
Male sex cells
Male sex cells are known as sperm. They are in charge of carrying the genetic information of the father to the ovum during the fertilization process.
They are much smaller in size than eggs, and are divided into several parts:
- A head, which contains the chromosomes that will be transmitted to the next generation, as well as the nutrients necessary for the cell to perform its function.
- A neck, in which the mitochondria are located. These are responsible for transforming nutrients into energy within the sperm.
- A tail, which, using the energy provided by the mitochondria, moves the sperm until it reaches the egg for fertilization.
Sperm are produced in large quantities in the testicles of males. However, only one is necessary to fertilize the female egg.
Female sex cells
Female sex cells are known as ovules in animal species. They are produced inside the ovaries.
These are relatively large cells, spherical in shape and which remain immobile once created.
In humans, they occur approximately once every 28 days, leading to menstruation if they are not fertilized.
The female body produces much fewer sex cells than the male throughout its life, so its fertile period is much shorter.
Once fertilization occurs within the mother's body, she stops producing new eggs until the moment the baby is born.
References
- "Sex cells" in: Natural Sciences. Retrieved on: November 27, 2017 from Natural Sciences: Ciencias-naturales79.webnode.com.co
- "Sex cells" in: Salud Movera. Retrieved on: November 27, 2017 from Salud Movera: saludmovera.jimdo.com
- "Sex cells" in: Ecured. Retrieved on: November 27, 2017 from Ecured: ecured.cu
- "Gameto" in: Wikipedia. Retrieved on: November 27, 2017 from Wikipedia: es.wikipedia.com
- "Sex cells" in: Yes - Educa. Retrieved on: November 27, 2017 from Si - Educa: si-educa.net