Genetics Lab Report Example | Topics and Well Written Essays - 1500 words

Genetics - Lab Report Example Therefore, during the meiosis, four meiotic sexual haploid cells with altered heredity are produced and then genetic information is mixed. The second meiotic division is the same as mitosis one. As in mitosis, in meiotic anaphase II the single sister chromosomes (called chromatids) separate and move to opposite poles of the cell1. Meiosis is the basis of sexual reproduction because it occurs in maturing germ cells and leads to the appearing of new hereditary characteristics in the chromosomes. Gene is the coding DNA sequence that placed in the specific locus on the chromosome. Such coded chains displayed in different traits, such as color of skin or length of the stem. Allele is a variant of gene and can be dominant or recessive. For example, in diploid organism one gene contains two alleles; therefore, traits can be different. If both alleles are identical, the gene locus is homogenous. When alleles are different, such gene locus called heterogenic. A good example is the Huntington disease. Huntingtons disease has the autosomal dominant inheritance. Consequently, an affected person has at least one mutant allele of Huntingtin gene (HTT)2. The child, whose one parent is homogenous by disease, carries two different alleles of the HTT gene and is heterogenic by this gene. Therefore, this child inherited a mutant allele of HTT gene and the Huntingtons disease will progress. Another example is blood groups. Gene locus that encoded blood groups has three alleles — IA, IB, and IO3. These alleles determine compatibility of blood transfusions. The person carries one of the six possible genotypes – AA, AB, BB, AO, BO and OO. Each of genotypes produce one of the four possible phenotypes: "AB" heterozygotes, and "O" homozygotes, "A" AA homozygous and AO heterozygous and "B" BB homozygous and BO heterozygous genotypes4. Crossing-over is the process that occurs in prophase I of meiosis while homologous chromosomes