GT Biology - Mrs. Alyson Donoghue

GT Biology March 8, 2011 Karyotypes Warm-up What type of mutations are the following? A ABCDEFG

ABCDEFGXYZ B ABCDEFG ABEDCFG C ABCDEFG

ABCBDEF G What is a karyotype? Objective SWBAT explain karyotypes and how they relate to mutations

Homework Read pgs 228-232 Answer questions 3-6 Today What are karyotypes? What do they tell us? How do they relate to genetic disorders?

What do these have in common? What do you think they show? Are they the same for all What is a karyotype

Karyotyping examines the chromosomes of a person An image of chromosomes Images are taken during metaphase Homologs are paired and arranged by size and shape How to obtain a karyotype There are two methods to obtain a

karyotype: A cell in mitosis is photographed Amniocentesis: amniotic fluid and cells from the fetus are withdrawn to be tested for a disease These are still in mitosis How can karyotypes be used? To study chromosomes and chromosomal

abnormalities To better explain genetic disorders Genetic Disorders What do you think a genetic disorder is? Can you tell if someone has sickle cell anemia from a karyotype?

Genetic Disorders Definition: an illness that is caused by an abnormality that occurs within a gene or chromosome Polyploidy It is possible for some cells and organisms to have more than one set of pair homologs Happens during mitosis or meiosis

Results in cells that are 3n, 4n, 5n or more This most often occurs in plants but can occur in animals Plants and fruits grow bigger than normal These animals are often sterile How could this be beneficial to farmers? Types of Genetic Disorders Nondisjunction: the addition or deletion of a

whole chromosome During anaphase I chromosomes do NOT separate The cell with an additional chromosome is called trisomy once fertilization occurs The cell with a deletion of a chromosome is called monosomy once fertilization occurs Trisomy 21: Downs Syndrome

Caused by nondisjunction Symptoms of Downs Syndrome: Small skull Abnormally round head Slanting eyes Short hands

Small mouth and enlarged tongue Low muscle tone Another Example of Trisomy Trisomy: Kleinfelters Syndrome (a male who has feminine features) Symptoms of Kleinfelters Syndrome

Male infertility Small testicles Round body type Difficulty reading, writing and language problems Example of Monosomy

Monosomy: Turners Syndrome (a female who has prepubescent features) Symptoms of Turner Syndrome Short stature Low hairline No menstruation Small finger nails Shield Shaped

Thorax Folds of skin on the neck Cri-du-chat Syndrome The loss of part of chromosome 5 Symptoms: stomach, intestinal and heart problems and mental retardation Use of Karyotypes

After learning about these types of genetic disorders, how do you think karyotypes could be of used?