Hardy Weinberg!

The Hardy Weinberg equation is the mathematical equation used to calculate the genetic variation of a population at equilibrium. The equation starts off with p^2 + 2pq + q^2. p + q also equals 1. P squared represents the frequency of the homozygous dominant allele, Two p q represents the frequency of the heterozygous allele, and q squared represents the frequency of the homozygous recessive allele. The two men who came up with this were Godfrey Hardy and Wilhelm Weinberg. They also stated that evolution in a population would not occur if the following happen: mutation does not occur, natural selection does not occur, the population is infinitely large, all members of the population breed, all mating is totally random, everyone produces the same number of offspring, and there is no migration in or out of the population. Going back to the equation, here is an example of a problem:

1. You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following:
1. The frequency of the "aa" genotype.
2. The frequency of the "a" allele.
3. The frequency of the "A" allele.
4. The frequencies of the genotypes "AA" and "Aa."

The frequency of the aa is already mentioned in the problem, 36%. To find B, firs square root .36. The answer is .6. So the frequency is 60%. For C, since q+p=1, and q=.6 then p=.4. So 40%. For D, .4 squared is .16 so the frequency of the AA is 16% and 2pq is equal to 2 times .4 times .6 so .48 or 48%.

Here is a good video about this:

Hardy Weinberg Video

Immune System Quiz

The Questions:

1. The innate immune system is also known as the non-specific immune system. The cells of the non-specific system recognize and respond to the pathogens in a generic way, but do not have long-lasting immunity to the host. The non-specific system recruits immune cells to the site of the infection, by the production of chemical factors, such as specialized chemical mediators called cytokines. It activates the complement cascade which identifies bacteria, activates cells, and promotes the clearance of dead cells or antibody complexes. It uses the process of antigen presentation to activate the adaptive immune system. It uses white blood cells to identify and remove foreign substances. It also acts as a chemical and physical barrier to infectious diseases. Innate immunity also includes external barriers of the body, which help prevent diseases from coming into the body.

2. There are two types lymphocytes (white blood cells): B lymphocytes and T lymphocytes. Lymphocytes start out in the bone marrow. If they stay in the bone marrow and mature there, they are B cells. If they leave for the thymus gland, they mature into T cells. Many kinds of cells work together and respond to foreign substances that invade the body (antigens.) These specific cells trigger B cells to produce antibodies, which are specialized proteins that attach onto specific antigens. Some T cells create chemicals for memory cells. This helps the body in defense against the same disease in the future. Other T cells help destroy antigens.

3. B and T cells produce memory cells. These specific cells hold information about previous threats and diseases to the body. All this gives the system a memory, meaning that the system will have a quicker and more powerful response to the disease in the future. This also helps our bodies to develop immunities, meaning that the system knows what the antigens already is and can stop new infections.

4. Body cells carry distinctive molecules that help identify it as itself. An antigen shows that it is foreign by characteristic shapes (or receptors) called epitopes, which stick out from the surface. Because the body does not recognize these receptors, the immune system will attack it. Other cells with the same "self"markers, are not affected by the immune system.