Block Day- April 18, 2012 Homework: None Make an entry: Entry 37: Mitosis vs. Meiosis-4/18/12 Complete the chart

Mitosis vs. Meiosis 1)Meiosis 2)Meiosis 3)Mitosis 4)Meiosis 5)Meiosis 6)Mitosis 7)Both 8)Mitosis 9)Meiosis 10)Mitosis 11)Mitosis 12)Meiosis 13)Meiosis

Make an entry Entry 38: Karyotypes-4/18/12 Definition: A karyotype is a picture of a person’s chromosomes.

Cut out from picture and match each in pairs In a karyotype, homologous pairs of chromosomes are matched and labeled.

How do we identify homologous chromosome pairs? 1.Size 2.Stain with a dye to produce a pattern of bands (banding pattern) 3.Position of the centromere Centromere

Gender determination Females have 2 “X” chromosomes. Males have 1 “X” and 1 “y” chromosome. X Female X y Male

Why make karyotypes? Some diseases are caused by problems with chromosomes –Extra chromosomes –Missing chromosomes –Broken chromosomes Making karyotypes allows scientists to identify these diseases. Example karyotypes Using karyotypes to predict disease

Chromosomal Abnormalities Caused by problems in Meiosis –Errors in MeiosisErrors in Meiosis Cannot be detected until the embryo (baby) is already made

Detecting Chromosomal Abnormalities Amniocentesis

Chromosomal Abnormalities Some chromosomal abnormalities are linked to maternal age (Down’s Syndrome)

Amniocentesis High-Risk mothers and mothers who have odd test results may get an Amniocentesis –An “amnio” is a sample of the amniotic fluid that surrounds the baby. This fluid contains the baby’s cells.

Amniocentesis From the Amniocentesis, a karyotype can be made.

Disease (extra chromosome) Normal (complete set of chromosomes)

Karyotype Lab Get a laptop, write down your number - log in to computer and wait! Go to the pickup work folder and open the document “Links for Karyotype Lab” Using the links- complete the fill in the blank notes on the chromosomal disorders: Down, Turner, and Kleinfelter syndromes.

When you are finished- Tape this into the Karyotype entry - Shut down your laptop