Genetics

Genetics is a study comprised of genes that pass down from parents to children , generation after generation.

Gregor Mendel was a monk who began dabbling in this science, and his studies of genetics in pea plants are world famous. Early beliefs were that (for example) if your father had black hair and your mother was blond, you would have brown hair. Gregor Mendel was the first to test this theory, and eventually it was proved wrong.

The Punnett Square is a simple diagram to display the possible ratio of the offspring, after the genotype (genetical make-up) of the parents is determined. One must first solve the problem of how many combinations of genes are possible in each sex cell, or gamete.

Every cell in the human body contains chromosomes, or the genetical make-up of the body. A trait is a certain factor in your genotype (hair color, eye color, height, etc.) and the allele is what the trait actually is (black hair, brown eyes, tall, etc.)

In a normal body cell, multiplication occurs during mitosis. In a sex cell, meiosis occurs. Meiosis is similar in some ways to mitosis, but not in others. It goes through eight stages. In the first four, two identical cells form from one cell. The process goes one step further in the next four stages. Each of the cells then divides again, this time each has only half the chromosomes. This is also known as a haploid cell. The result of mitosis is a diploid cell. (a cell with the normal amount of chromosomes)

Alleles are the different forms of genes. An allele can be a homozygote, heterozygote, dominant, or recessive. A homozygote contains the genetic make-up for either dominant (form of a gene that is expressed even if a recessive allele is present) or recessive (allele only expressed in the homozygote state). A heterozygote contains both the dominant and recessive forms of genes, therefore, only the dominant allele is expressed. A homozygote organism can also be called a purebred, while a heterozygote organism can be called a hybrid.