1. Chapter 11.3 Pg. 311

2.  Pairs of homologous chromosomes are arranged in decreasing size to produce a micrograph called a karyotype  Scientists have found that chromosomes end in protective caps called telomeres  Telomere caps consist of DNA associated with proteins

4.  Telomeres also might be involved in both aging and cancer

5.  Cell division during which sister chromatids fail to separate properly, which does happen occasionally, is called nondisjunction  Nondisjunction can result in extra copies of a certain chromosome or only one copy of a particular chromosome  Set of 3 chromosomes of one kind is called Trisomy

6.  Only one of a particular type of chromosome is called monosomy  Alterations of chromosome number are associated with serious human disorders, which are often fatal

7.  one of the earliest known human chromosomal disorders  Result of an extra chromosome 21(trisomy 21)  Distinctive facial features, short stature, heart defects, and mental disabilities

8.  Frequency in the US: 1/800 children are born with Down Syndrome  Frequency also increases with increasing age of mother ◦ 6% increase in chance with mothers who are 45+ www.downsyndrome.com

9.  Couples who suspect they might be carriers for certain genetic disorders might want to have a fetal test performed  Test can only be performed if both mother and unborn child are in good health

10. TESTBenefitRisk Amniocentesis-Diagnosis of chromosomal abnormalities -Diagnosis of other defects -Discomfort for mother -Slight risk of infection -Risk of miscarriage Chorionic villus sampling (placental sample) -Diagnosis of chromosomal -Diagnosis of certain genetic defects -Risk of miscarriage -Risk of infection -Risk of newborn limb defects Fetal blood sampling-Diagnosis of genetic or chromosome abnormalities -Checks for fetal blood problems and O 2 levels -Medications can be given to the fetus before birth -Risk of bleeding from sample site -Risk of infection -Amniotic fluid might leak -Risk of fetal death

11. http://player.discoveryeducation.com/index.cfm?guidAssetId=AB274E B9-EDF1-40F0-9122- 5B996E8E08E0&blnFromSearch=1&productcode=US