GENETICS AFTER MENDEL IMMUNOLOGY Red blood cells consist

GENETICS AFTER MENDEL

IMMUNOLOGY Red blood cells consist only of hemoglobin contained in a protein membrane. The body recognizes its own proteins. Antigens are proteins that trigger an immune reaction. Any foreign protein entering the blood stream is an antigen and will be flagged for destruction by a white blood cell. This Photo by Unknown Author is licensed under CC BY-SA

BLOOD GROUPS The A and B alleles are codominant This Photo by Unknown Author is licensed under CC BY-SA-NC Karl Landsteiner

RH BLOOD GROUP The Rhesus blood group system is second in importance to the ABO system. It involves 49 antigens, 5 of which are important for transfusion. The D antigen figures in someone having the + phenotype designation (possesses the antigen) or – One’s ABO genotype has no bearing on whether someone is rhesus positive or negative, conforming to Mendel’s principal of independent assortment.

FEARS CONCERNING ALLELES: HYPERTROPHIC CARDIOMYOPATHY Hypertrophic cardiomyopathy is a condition where the tissue of the walls of the heart’s two principal chambers is abnormally thick. The tissue is the product of a dominant allele. This Photo by Unknown Author is licensed under CC BY-SA When people became aware that negative health conditions could be caused by dominant as well as recessive alleles, they also became concerned that dominant alleles were predestined to multiply in a population.

POPULATION GENETICS Scientists working in the field of population genetics track the changes in allele frequencies over generations. The mathematician Godfrey Hardy and Obstetrician Wilhelm Weinberg independently developed a model that represented a population in genetic equilibrium, that is, the frequencies of the alleles of a gene are not expected to change unless some force or behavior acts on it. P 2 + 2 pq + q 2 = 1 This Photo by Unknown Author is licensed under CC BY-NC-ND

HARDY-WEINBERG EXPLAINED P = the frequency of one allele q = the frequency of the other allele. P 2 = one homozygote genotype frequency. 2 pq = the frequency of the heterozygote. q 2 = the frequency of the other homozygote genotype. This Photo by Unknown Author is licensed under CC BY-SA