GN 301 1st EditionExam # 2 Study Guide Lectures: 12 - 20Mutations- Not all mutations are bad!- Mutagen: something (physical or chemical) that alters DNA- Point Mutations: only one base pair is altered (AAA BBB -> AAZ BBB)o Example: In Sickle Cell Anemia, the codon GAG (Valine) is changed to GUG (glutamic acid), allowing individuals heterozygous for SSA to be more resistant to malaria.- Frameshift Mutation: the insertion or deletion of base pair(s)- A nuclear disaster at Fukushima occurred in 2011.Effects of the Environment- Hereditary Defect: a defect that may be passed through generations- Congenital Defect: a birth defect; present at birth- Phenocopy: an individual with characteristics similar to a genotype other than its own- Carcinogen: a substance that may cause cancer- Mutagen: something that alters DNA- Teratogen: something that causes damage to embryotic developmento Example: Alcohol and Fetal Alcohol Syndrome; if a mother were to drink during pregnancy the child could be mentally and physically handicappedChromosome Variation- Deletion: an instance where part of the chromosome is missingo Example: William Syndrome, Cri du Chat- Duplication: extra genetic material from a duplication segment of DNA- Inversion: the chromosome breaks and rearranges within itself, misplacing DNA segments- Translocation: rearrangement of DNA between nonhomologous chromosomeso Example: Burkitt’s Lymphoma, familial down syndrome- Aneuploidy: the number of chromosomes is not a multiple of the haploid number- Rachel Gillen has Down SyndromeMendelian Inheritance- Law of Random Segregation: every individual has a pair of alleles for each trait that separate during cell division- Law of Independent Assortment: in a cross between traits, the part responsible for eachtrait is distributed to the gametes- Penetrance: measures the proportion of carriers’ phenotypes- Expressivity: refers to variations in a phenotype among individuals with a specific genotype- Epistasis: interaction of nonallelic genes - Pleiotropy: one gene influences many phenotypic traitsSex Determination, Sex Linkage, Gene Expression- SRY Gene: Sex Determining Region Y: Allows the fetus to develop into a male, located on the Y gene- Ovotestes: present in early fetus, changes to ovaries or testes- Barr Body: an inactive X chromosome in the female somatic cello Since one X chromosome is randomly turned off, only the characteristics of one Xchromosome is displayed, making women mosaics.- A change from female to male is more easy to accomplish.- Homozygous: only containing one type of allele (AA, aa)- Heterozygous: containing two types of alleles (Aa)- Hemizygous: only one copy present (XY)- Holandric: A trait that only affects males (Grandfather to grandson, etc)- Sex Linked: a trait that tends to be associated with one sex or the other- Sex Limited: a trait exhibited by only one sex or the other- Sex Influenced: autosomal traits that are differently