Mendelian Genetics
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Gregor Mendel was a monk who, in the 1800s, studied the inheritance patterns in strains of garden peas (Wilson, 2000, 137). The importance of his work was not recognized until well after his death, but a whole field of genetics is now named after him, and his early studies lay the basis for the study of genetic inheritance. Between 1856 and 1863, Mendel grew and tested over 28,000 pea plants (biopoint.com, 2004). His carrying out his experiment using peas was fortuitous because they have a relatively simple genetic structure, and their breeding could be controlled so that he could be sure of the parents of his plants. He only measured absolute characteristics such as size, shape, and color, and he used large sample sizes. Mendel's numerical recording of his results and statistical analyses gave credibility to the results he obtained. By examining several successive generations of plants, he was able to develop his first and second laws of inheritance. Mendel's law of segregation has four parts: alternative versions of genes give rise to variations in inherited characteristics; for each character, an organism inherits one gene from each parent; if two alleles differ, the dominant one will be fully expressed in the organism's appearance; and the two genes for each character separate during gamete production (biopoint.com, 2004). Mendel's law of independent assortment is that genes for different traits separate independently during phenotype is thei
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be homozygous for that gene, and if the two alleles are different, they are said to be heterozygous for that gene. An individual's genotype is their genetic makeup.
Sex-linked Inheritance
Human females inherit two X chromosomes and human males inherit one X and one Y chromosome (Wilson, 2000, 151). Because males have only one X chromosome, recessive inheritance works differently if the gene is on the X chromosome. In the case of red/green color blindness in humans, the mutant allele is on the X chromosome. If a female is a carrier of the mutant gene (XX*) and her husband has the normal gene (XY), half of the female offspring will be carriers and half of the male offspring will have the disorder.
Karyotype Production and Significance
A karyotype is an individual's chromosome profile and is produced by arranging pictures of the chromosomes in order of size from the largest to the smallest, using their banding pattern and centromere position as a guide (Genetic Science Learning Center, 2003). The most important way to separate chromosomes is by size. Next, when the chromosomes are stained using a Giemsa stain, bands appear, and the size and location of these bands is characteristic for each pair of chromosomes. The po
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Approximate Word count = 1536
Approximate Pages = 6 (250 words per page)
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