Bellringer Please add questions (2 per page) and a summary to your Blood Types and Sex-Linked Notes. Summary 3 things you learned 2 things you found interesting 1 question you still have Get out Blood Types and Sex-Linked Practice Problems, so I can come and check that you completed them.

Learning Target Summarize the chromosome theory of inheritance, including genetic linkage and the process of crossing over. Understand the cause of common genetic disorders such as non-disjunction, damaged chromosomes, and mutations.

Genetic Disorders

Chromosomes Remember Chromosomes contain our genes for traits. Chromosome theory of inheritance: Genes are located on chromosomes. Genetic Linkage: Linked genes sit close together on a chromosome, making them likely to be inherited together. Loci: Location of a gene on the chromosome.

Crossing Over During Meiosis Reminder: Crossing over occurs during meiosis in prophase I, two homologous pairs of chromosomes pair up and exchange segments of their genetic material.

What if something goes wrong during Meiosis?  What if something goes wrong during Meiosis? What would happen if a homologous pair failed to separate during Anaphase I?

 Nondisjunction Homologous chromosomes fail to separate during Anaphase 1 of meiosis Some cells have EXTRA chromosomes, and others with MISSING chromosomes!

Down Syndrome (Trisomy 21)  Down Syndrome (Trisomy 21) Trisomy (3 copies) of chromosome 21 (as a woman ages her chances of producing offspring that have Down Syndrome increases)

Klinefelter Syndrome (XXY)  Klinefelter Syndrome (XXY) XXY condition Mainly from nondisjunction in mother (67%) Tall males Sterile or nearly so Feminine-like traits (sparse facial hair, somewhat enlarged breasts) Treated with testosterone injections

XYY Condition  Male Taller than average Normal development and sexual characteristics Some mentally impaired Once thought to be predisposed to criminal behavior, but studies now discredit

 Turner Syndrome (XO) Female, inheritance of only one X (XO) 98% of XO babies are miscarried Short, infertile females, with no functional ovaries and reduced secondary sexual traits May be treated with hormones, surgery

Other Causes of Chromosomal Disorders: Remember talking about these chromosomal mutations?!? -Deletion: Part of chromosome segment is taken out. -Duplication: Part of chromosome segment is repeated. -Inversion: Part of chromosome segment is reversed. -Translocation: Two non-homologous chromosomes swap genetic information.

Genetic Disorder Activity Turn in lab manual to How Are Genetic Disorders Identified in Humans? Activity. Answer questions 1-7 over genetic disorders. Once done, please stack lab manual on the front table. You may work on your vocabulary with the remaining time left in class.