1. Chromosomal Mutations & Karyotypes

2. Chromosomes Sex chromosomes: X and Y XX: female (one X is deactivated)
XY: male (both are active)
Autosomes: all other chromosomes
humans have 46 chromosomes – 44 autosomes and 2 sex chromosomes

3. DIPLOID
DIPLOID
Tetrad

4. Karyotype: a picture of chromosomes arranged into homologous pairs

6. Mutations-occur during crossing over!
deletion: a whole section of the chromosome is removed
duplication: a whole section of the chromosome is duplicated
inversion: a section of the chromosome is removed and reattached upside down
translocation: part of one chromosome attaches to a non-homologous chromosome

8. Disorders-caused by nondisjunction!
Nondisjunction: homologous chromosomes fail to separate during meiosis – results in too many or too few chromosomes

10. Disorders-caused by nondisjunction!
Aneuploidy: abnormal number of chromosomes in a cell
Monosomy: Missing a single chromosome
Trisomy: Has an additional chromosome

11. Disorders-caused by nondisjunction!
Monosomy
Trisomy

12. Karyotype Notation
Format: Total number of chromosomes, the sex chromosomes, and any extra or missing autosomal chromosomes
Format if it involves the sex chromosomes: Total number of chromosomes, sex chromosomes
Ex: 47, XY, +18 indicates that the patient has 47 chromosomes, is a male, and has an extra autosomal chromosome 18
Ex: 46, XX is a female with a normal number of chromosomes

13. Disorders-caused by nondisjunction!
Down syndrome: (trisomy 21) three copies of chromosome 21
Turner syndrome: (monosomy X) only one X chromosome
Klinefelter’s syndrome: (XXY) trisomy 18 and trisomy 13 are also possible