Station 9 Genetic Variations Reporting Category 2 Mechanisms of Genetics

Essential Question – Bell Ringer Hemophilia is a sex-linked trait that is carried on the X chromosome. Why is there a higher probability that males will exhibit the characteristics of hemophilia than females?

Essential Question – Bell Ringer Hemophilia is a disease, carried only on the X chromosome in humans, that prevents blood from clotting properly. Males have one X and one Y sex chromosome, so the hemophilia gene can appear on only one chromosome in males—but males need only one hemophilia gene to exhibit the characteristics of the disease. Females have two X chromosomes and thus have an increased chance of carrying the gene on one of the chromosomes. However, the gene must be present on both X chromosomes in order for females to exhibit the characteristics of hemophilia. Therefore, males are more likely than females to exhibit the characteristics of hemophilia.

Pre-Preview Question Genotypes for fruit fly wings W = Normal Wings w = wrinkled wings What are the phenotypes? Ww - ww - WW - Normal Wings Wrinkled Wings Normal Wings

Pre-Review Question If Mary and Tom have a child, what is the probability that they will have a boy? XY X1?2? X3?4? XX XY XX XY 50% Boy 50% Girl

Pre-Review Question If Mary is a carrier for hemophilia (sex-linked, recessive) and Tom does not have hemophilia, what are the possible genotypes for their offspring? XHXH Y XHXH 1?2? XhXh 3?4? XHXHXHXH XHYXHY XHXhXHXh XhYXhY 1/4 chance of having a child with hemophilia What is the probability they will have a child with hemophilia?

Lab Activities You will now go back to the lab and complete the activities for today’s topic.

Practice R – Red eyesW – normal wings B – Normal bristlesY – Yellow body r – white eyesw – wingless b – no bristlesy - black body The white charts above contain the alleles for several fruit fly traits. 1.Cross the male and female for wings. What is the phenotypic ratio for the F1 generation?

Practice R – Red eyesW – normal wings B – Normal bristlesY – Yellow body r – white eyesw – wingless b – no bristlesy - black body The white charts above contain the alleles for several fruit fly traits. 1.Cross the male and female for eye color (Remember this is a sex linked trait). What is the phenotypic ratio for the F1 generation?

Practice R – Red eyesW – normal wings B – Normal bristlesY – Yellow body r – white eyesw – wingless b – no bristlesy - black body The white charts above contain the alleles for several fruit fly traits. 1.Complete a dihybrid cross for bristles and body color. What is the phenotypic ratio for the F1 generation?

I need to be able to…….. Analyze and make inferences about dominant and recessive traits. Interpret and make predictions about genotypes and phenotypes Determine and interpret phenotypic ratios. Understand the difference between Mendelian and non-Mendelian traits. Use Punnett squares and other models to predict the results of genetic crosses involving X-linked traits. Interpret results and make predictions from monohybrid and dihybrid crosses.

Post Review Question Homozygous Dominant Homozygous Recessive Heterozygous Which term above can be represented with the following alleles? AA Homozygous Dominant

Post Review Question Homozygous Dominant Homozygous Recessive Heterozygous Which term above can be represented with the following alleles? Aa Heterozygous

Post Review Question Homozygous Dominant Homozygous Recessive Heterozygous Which term above can be represented with the following alleles? aa Homozygous Recessive

Post Review Question Non-Mendelian Genetics Incomplete Dominance RR – Red WW- White If a red flower and a white flower are crossed, what will the phenotype of the F1 generation be? RW = Pink

Post Review Question Non-Mendelian Genetics Co Dominance BB – Brown WW- White If a brown cow and a white cow are crossed, what will the phenotype of the F1 generation be? BW – brown and white spots