Block Day- April 18, 2012Homework: None

Make an entry: Entry 37: Mitosis vs. Meiosis-4/18/12Complete the chart

Mitosis vs. Meiosis1)Meiosis2) Meiosis3)Mitosis4) Meiosis5)Meiosis6) Mitosis7)Both

8)Mitosis9) Meiosis10)Mitosis11)Mitosis12)Meiosis13)Meiosis

Make an entryEntry 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. Size2. 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 XFemale

X yMale

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 karyotypesUsing karyotypes to predict disease

Chromosomal Abnormalities• Caused by problems in Meiosis

– Errors 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