1. Chromosomes and Human Heredity Chapter 11.3

2. Karyotype Studies  Scientists do not only study genes – they also like to look at the chromosome at a whole using images of them stained  Pairs of homologous chromosomes are arranged in decreasing size to produce a micrograph called a _____________________  The protective caps of the chromosomes are called telomeres and consist of DNA associate with ____________

4. Karyotype Questions  Is this a male or a female?  How many autosomal chromosomes are there?  Are there any non-matched chromosomes?

5. Telomere  Scientists have discovered that telomeres also might be involved in both aging and cancer

6. Nondisjunction  In cell division, the chromosomes separate, creating the proper number of chromosomes in daughter cell  When sister chromatids fail to separate properly we call this nondisjunction  If this occurs, the resulting gametes will not have the correct number of chromosomes  therefore when the gametes are ________________ the offspring will not have the correct number of chromosomes

7. Nondisjunction  This can result in extra copies of a certain chromosome or only one copy of a particular chromosome  A set of _______ chromosomes of one kind is call trisomy  One singular type of chromosome is called _______________________

9. Down Syndrome  Is the result of an extra chromosome 21 therefore it is often called _______________________  The frequency of this disease is one out of 800 and increases with Mother’s age  Over the age of 45, 6% of the time a mother will have a child with downs

10. Fetal Testing  If couples suspect they are a carrier for a disorder or they are older, they may test their fetus for signs of a disease  Amniocentesis  Diagnose chromosome abnormalities or other defects  Chorionic villus sampling  Diagnosis of chromosome abnormality or genetic defects  Fetal blood sampling  Diagnosis of genetic/chromosome abnormaility, check for fetal blood problems and Oxygen levels, medications can be given to the fetus before birth