Describe and difference between mitosis and meiosis
Complete Punnett Squares in order to predict patterns of inheritance
Discuss the process and ethics of cloning
Mitosis produces identical copies of cells, and is involved in growth, cell repair and asexual reproduction - which is how simple organisms reproduce. When cells divide by mitosis, two new cells form and each cell is identical to one another and also the parent cell. This means that the number of cells increases, and hence the organism grows.
Meiosis a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.
A Punnett square is used to predict the chances of an offspring to have its parents' traits. These squares are most commonly divided into four parts, with each part equalling a 25% chance of the offspring receiving that set of genes. More complicated squares may have more than four parts, though the same basic method applies.
The letters surrounding and within each square represent alleles. They are one part of a gene pair occupying a specific part of a chromosome. All dominate alleles have capital letters, while the recessive ones are lowercase. Dominate alleles will always overpower recessive ones in the expression of the gene.
If the alleles for a parent do not match, they are known as heterozygous. In the image above the Gg is heterozygous. This can happen if there is a dominate and a recessive gene in the parent. If the alleles are the same for that expressed gene, it is known as homozygous. This is seen if both alleles are dominate or if both alleles are recessive; e.g., GG or gg. In order for a recessive gene to be expressed, the alleles must be homozygous.
Each father and mother pass down traits to their children, who inherit combinations of their dominant or recessive alleles. But how do we know so much about genetics today?