For Questions 1-6, match the labels to the parts of the pedigree chart shown below. Some of the labels may be used more than once.   1. A person who expresses the trait 2. A male 3. A person who does not express the trait 4. A marriage 5. A female 6. A connection between parents and offspring

March 21, 2012 BellRinger Objectives Homework Pedigree Conduct a chi-squared analysis to determine the validity of a hypothesis Recognize the inheritance patterns of recessive, dominant, and sex-linked traits in pedigrees Homework Chp 15 notes (sec 4&5) Chp 14 & 15 quiz on Friday

Chi-squared Analysis The actual results of an experiment are unlikely to match the expected results precisely. But how great a variance is significant? One way to decide is to use the chi-square (x2) test. Analytical tool tests the validity of a null hypothesis there is no statistically significant difference between the observed results of your experiment and the expected results. little difference between the observed results and the expected results = very low chi-square value = your hypothesis is supported.

Calculating Chi-Square The formula for chi-square is: X2 = the sum of where: o = observed number of individuals e = expected number of individuals This value is then compared to a value on the critical values table to determine if your hypothesis accepted or rejected

Critical values Degrees of freedom. Probability. number is one less than the total number of classes of offspring in a cross. In a monohybrid cross there are two classes of offspring (red eyes and sepia eyes) = one degree of freedom. In a dihybrid cross, there are four possible classes of offspring = three degrees of freedom. Probability. probability value (p) = probability that a deviation as great as or greater than each chi-square value would occur simply by chance. Biologists use 0.05 (5%)

Genetics of Organisms Lab Return to your online notebook and complete a report using the data you accumulated yesterday There are questions that will prompt your thinking for each section Complete the optional quiz for extra credit Submit online by 12 midnight Sunday

For Questions 1-6, match the labels to the parts of the pedigree chart shown below. Some of the labels may be used more than once.   1. A person who expresses the trait 2. A male 3. A person who does not express the trait 4. A marriage 5. A female 6. A connection between parents and offspring

Pedigrees Create a pedigree using the information below: Dimples in the cheeks are inherited as a dominant trait on a gene. Using the proper form and symbols, draw a pedigree chart, beginning with a dimpled father (Dd), and a nondimpled mother (dd). Show four children of the expected types: boys, girls, dimples, and no dimples. Label your pedigree with phenotypes and genotypes.

Pedigrees Read the directions and work through the pedigrees on the handout In pairs, write down 3-4 rules that apply to the recessive allele inheritance patterns and 3-4 rules that apply to dominant allele inheritance patterns Share your results with another pair and pick out 2 rules-(one for dominant one for recessive) to share with the class

Rules for inheritance patterns Recessive allele inheritance patterns Unaffected parents can have affected offspring The phenotype can skip a generation Individuals with no sign of the allele can be carriers Dominant allele inheritance patterns Affected offspring must have at least one affected parent The phenotype appears in every generation without skipping Two unaffected parents have normal offspring

The pedigree below traces the inheritance of alkaptonuria, a biochemical disorder. Affected individuals, indicated here by the colored circles and squares, are unable to metabolize a substance called alkapton, which colors the urine and stains body tissues. Does alkaptonuria appear to be caused by a dominant allele or by a recessive allele? Fill in the genotypes of the individuals whose genotypes can be deduced. What genotypes are possible for each of the other individuals?  

Sex- linked Trait With a partner, you will construct a pedigree for a family with color-blindness 3 generations 2 sets of grandparents in the first generation 1 grandmother is a carrier for the trait 1 grandfather (on the other side of the family) is colorblind 8 people in the second generation (4 male, 4 female) 1 male and 1 female are married 6 people in the 3rd generation (half male, half female) Use the genotypes XBXB for a normal female, XBXb for a female carrier, XbXb for a female who is colorblind XBY for a normal male, XbY for a male who is colorblind

Rules for inheritance patterns Recessive allele inheritance patterns Unaffected parents can have affected offspring The phenotype can skip a generation Individuals with no sign of the allele can be carriers Dominant allele inheritance patterns Affected offspring must have at least one affected parent The phenotype appears in every generation without skipping Two unaffected parents have normal offspring