Explain why human skin coloration is not sufficiently explained by polygenic inheritance.
-Polygenic inheritance is the additive effects of two or more genes on a single phenotypic characteristic.
9.17
Describe the limits, benefits, and ethical challenges of genetic testing.
-Genetic testing can fall into one of the five categories: carrier testing, diagnostic testing, prenatal testing, newborn screening, and predictive testing. Carrier testing is designed to determine whether a person may potentially be carrying a harmful recessive allele that could be passed on to the offspring. They are given to people who have a family history of genetic disorder or to an ethnic or racial group that is known to be at a higher risk for the disorder. Diagnostic testing can confirm or rule out an existing disorder. It helps patients get suitable medical care and guides them to making important decisions. Prenatal testing is a test that checks for genetic disorders in unborn babies. New born screening catches inherited disorders right after birth, which allows infants to receive immediate medical attention. Predictive testing is for people who have a family history of a genetic disorder but has no symptoms. It determines a person’s risk for developing that disease in the future. Patients seeking genetic testing should receive counseling before and after to clarify family history, explain the test and to cope with the results. People who risk having a genetic disease may also avoid testing in fear of being denied health insurance or being shunned by family and friends.
9.18
Define the chromosome theory of inheritance. Explain the chromosomal basis of the laws of segregation and independent assortment
-The chromosomal theory of inheritance states that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns. Mendel’s chromosomal basis of the law of segregation occurs when the two alleles segregate as homologous chromosomes separate in anaphase 1. His chromosomal basis of independent assortment
9.19
Explain how linked genes are inherited differently from nonlinked genes.
- Linked genes are genes that are located close together on the same chromosome. They tend to be inherited together and therefore do not follow Mendel’s principle of independent assortment.
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