1. What was your favorite thing about winter break? What is a karyotype? What is the purpose of a karyotype?

2. Chapter 12 Section 1

3. All of an organism’s DNA can be packaged into chromosomes Humans - 23 pairs or 46 total chromosomes Each pair of chromosomes contain genes with 2 alleles (1 from each parent) Chromosome Numbers 1-22 autosomes Sex chromosomes “#23” XX – Female XY - Male

4. A karyotype is a picture of all chromosomes in a cell, for one organism Karyotypes can show: changes in chromosomes deletion of part or loss of a chromosome extra chromosomes

5. MaleFemale

6. A change in a genetic trait 1) chromosomal 2) gene mutation Germ cell (gametes) or somatic cell (body) Germ cell mutations can be inherited and somatic cell mutations result in cancers Can be lethal (even before birth)

8. loss of a piece of chromosome Cri du chat Wolf-Hirschhorn syndrome

9. Inversion: chromosome breaks off and reattaches in reverse Translocation: piece breaks off and attaches to another * No problems in an individual since all genes are intact but there are problems with crossing over during meiosis

10. Nondisjunction: failure of a chromosome to separate from its homologous chromosome Trisomy - one too many chromosomes (2n=47) EX Down Syndrome, Kleinfelter’s Syndrome (XXY) Monosomy - only one of a homologous pair (2n=45) EX. Turner Syndrome (X)