The cell is the basic unit of all the living organisms. It contains many important structures like chromosomes, which are responsible for the genetic makeup of an organism (Wasserman 111). The cells of an organism undergo a process known as cell division. In this process, a parent cell splits into two or more daughter cells (Wasserman 111).
There are two types of cell division namely meiosis and mitosis. It is pertinent to note that, difference is that in mitosis the number of the daughter cells are two whereas, meiosis creates four daughter cells (Wasserman 120). Another thing that differentiates the two types is that mitosis takes place in the somatic cells only while meiosis happens in the gametes (Wasserman 120).
The offspring acquire the genes, which are the units of heredity from the parents by inheriting chromosomes. These genes are passed from generation to generation through gametes (Wasserman 131).This passage of genes from parents happens in either asexual reproduction or in sexual reproduction. In asexual reproduction, there is fusion of gametes of the parents as opposed to sexual reproduction where two parents give rise to an offspring through fusion of the gametes from each parent (Wasserman 132).
During inheritance, some changes in the organism’s DNA termed as mutations may occur and this leads to genetic variation. The three major mechanisms responsible for genetic variation are crossing over. Moreover, random fertilization, as well as, independence of chromosomes occurs (Wasserman 133).
In multi, cellular organisms there are two varieties of sex chromosomes; the X chromosome and the Y chromosome. Therefore, there is a chromosomal basis of sex determination (Wasserman 150). Each ovum has an X chromosome while the sperm may contain X or a Y chromosome. A female offspring needs two sets of X allele (XX), a condition known as homozygous while a male need only one of the X allele (XY). This is known as heterozygous (Wasserman 151).
Works cited
Wasserman, Steven. Campbell Biology. Lincoln: Benjamin Cummings Publishers, 2012.
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