Nursing Preparation Study Guide

Nursing Preparation Study Guide Genes contain two alleles, one from each of our parents. When we reproduce, we will transfer one, and only one, of each allele to our children. Alleles can be either dominant or recessive, and by combining the pairs of alleles we get from our parents, we can determine what our genes say we should be like (genotype). Under normal circumstances people’s genes will transfer directly from their parents following Mendel’s Laws of Inheritance; however, it is important to note that errors are common. DNA reproduction, however, is not necessarily a flawless process. Errors can develop either at randomor due to outside influences, such as radiation or chemicals in the environment. These errors, when related to heredity, are called de novo mutations, and they occur during embryonic development. Other mutations have no effect at all on the person’s genetic makeup, yet some can alter the way genes are expressed. Whether or not this is a positive result depends entirely on which genes are altered in which ways. Some mutations may cause children to be born sick or to have an increased vulnerability to disease by altering the types of proteins their genes produce, or even by stopping certain proteins from being produced at all. Others, though, can be an improvement to the child’s genetic structure. It is important to remember that the entire process of evolution is based on how random mutations throughout history have affected an individual’s ability to interact with the environment. Several notable examples of beneficial mutations stemming from natural selection can be seen in bubonic plague-resistant European populations and malaria-resistant African populations. Both groups have genes built from specific alleles that create disease blocking proteins. The CCR5 protein in people of European descent blocks the plague and, in some cases, HIV; the sickle cell protein in people of African descent blocks malaria. These genes are widespread throughout their respective populations as a result of natural selection, which killed those who lived in these groups’ ancestral regions, but who did not possess the mutation. Had these diseases never existed, the mutations would have been considered neutral, providing no benefit, yet causing no harm. There are several ways that errors in DNA reproduction can cause mutations. Chemicals can be inserted into, or deleted from base pairs, causing the chemical composition of the pairs to change and, thus, changing the alleles of the gene represented by those pairs. A portion of the DNA strand may also duplicate itself, or shift, triggering the half of the base pair on one side of the DNA strand to link to the wrong half on the other side. Heredity: Mendelian Inheritance The father of genetics was a 19 th century Austrian monk named Gregor Johann Mendel, who became famous for his work crossbreeding peas in the garden of his monastery. Aside from his life as a monk, Mendel was a highly educated physicist, studying first at the University of Olomouc (in the modern-day Czech Republic) and later at the University of Vienna.

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