Meiosis is the type of cell division that produces gametes, the reproductive cells of a sexually reproducing organism. During meiosis, the genetic material replicates and is divided between daughter cells so that each gamete contains a single copy of each chromosome instead of two copies.Know More
Meiosis only occurs in primordial germ cells in the reproductive organs and not in somatic cells, which make up the majority of the cells in the body. In males, meiosis is called spermatogenesis because it produces sperm cells. In females, the process is called oogenesis because it produces egg cells, also known as ova. In spermatogenesis, four fully functioning sperm are produced at the end of meiosis. In each round of oogenesis, only one fully functioning egg is formed, and the other three cells produced are non-viable polar bodies.
In some cases, errors occur during the process of meiosis. When the chromosomes do not segregate properly during meiosis, the resulting gamete ends up with too many or too few chromosomes. In most cases, the gamete or the resulting fertilized egg does not survive. Down syndrome is an example of a genetic disorder caused by an error in meiosis. Maternal age and environmental factors may contribute to meiosis errors, although in some cases errors occur simply as a result of natural inefficiencies in the process of cell division.Learn more about Molecular Biology & DNA
The two main differences in mitosis and meiosis are that meiosis involves only one cell division, not two, and meiosis results in the production of germ cells or cells that produce gametes. In mitosis, one round yields two genetically identical cells.Full Answer >
Heredity factors influence what an organism develops into because of genetic influences, whereas the environment plays a role in determining what the organism becomes. One example of this is height, which is partially determined by the person's genes, but is also determined by dietary differences.Full Answer >
Dominant alleles are always expressed in the organism, while recessive traits tend to be expressed only when the dominant allele is not present. The relationship between dominant and recessive genes is described by the Law of Segregation. As related by About.com, Gregor Mendel observed nine different traits among his pea plants and found that certain traits, such as pod color, bred true only when two recessive alleles were present.Full Answer >
An organism's genotype is the entire set of genes that it carries in its genome, and its phenotype is the observable effect of those genes on the body and behavior of the organism. Biologists draw a distinction between genotypes and phenotypes to clarify the difference between an organism's genetic heritage and the effects that its combination of genes has.Full Answer >