1. BICH107/GENE105 9-16-2008 pg 1 Features of a chromosome What is the function of a telomere? What is the function of a centromere? From Figure 13.6, pg. 245, Human Genetics 6th edition by R. Lewis Human chromosomes 1-22 are AUTOSOMES. We inherit one set from Mom and one set from Dad. The X and Y chromosomes are SEX CHROMOSOMES. We also inherit these from our parents. Male offspring inherit one X and one Y. Female offspring inherit two X chromosomes. replication

2. Meiosis - (pronounced my-o-sis) a process to convert a diploid cell to a haploid gamete, and cause a change in the genetic information to increase diversity in the offspring Here is a link to the Biology Project at the University of Arizona and a tutorial on meiosis: http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/main.html Vertical transmission of genetic information Most higher eukaryotes propagate through sexual reproduction that forms a new individual from two haploid sex cells (gametes). XXXY Possible gametes: All are X 1/2 are X & 1/2 are Y Genotype of sex chromosomes: Gametes from the female X X Gametes from the male XY Punnett Square XX XY Inheritance of sex chromosomes from parents to offspring BICH107/GENE105 9-16-2008 pg 2

3. Gregor Mendel studied the inheritance of stable traits with two easily distinguishable forms, like plant height (tall and short) in pea plants true talltrue short Tall phenotype is dominant over short Hybrid talltrue short T T tt Tt The short phenotype reappears in crosses with hybrid tall parent T t tt Tt tt Expect all hybrid tall plants Expect two hybrid tall plants and two short plants BICH107/GENE105 9-16-2008 pg 3

4. Inheritance of Dominant Disorders: A Fifty-Fifty Chance Adapted from http://www.hhmi.org/genetictrail/ BICH107/GENE105 9-16-2008 pg 4 n n Dn DnDn DnDn nn X X XY Inheritance of X-Linked Disorders: Males are at Risk XXYXY XXXY Inheritance of Recessive Disorders: One Chance in Four N N d d NNNdNd NdNddd

5. Single gene traits of humans ability to roll the tongue is dominant (R) non-rolling is recessive (r) ear lobes hang free is dominant (E) attached earlobe is recessive (e) left thumb is on top is dominant (C) the right thumb is recessive (c) A straight thumb is dominant (S) a bent thumb is recessive (s) Widow’s peak is dominant (W) a straight hairline is recessive (w) mid-digital hair is dominant (H) lack of mid-digital hair is recessive (h) BICH107/GENE105 9-16-2008 pg 5 little fingers bend away is dominant (B) straight little fingers are recessive (b)