1. The Human Genome Karyotype  Mapped out picture of chromosomes arranged in their homologous pairs.  46 chromosomes in human genome  23 pairs on karyotype

2. 2 Types of Chromosomes  Sex Chromosomes  Determine individual’s gender/sex  2 out of 46 (1 pair)  23 rd pair is always sex pair  Females: XX (2 X chromosomes)  Males: XY (1 X and 1 Y chromosome)  Autosomes  Non-sex chromosomes  Remaining 44 of 46 (22 pairs)  Pairs numbered 1 through 22

3. Determining gender…  Egg Cells-carry single X chromosome  Sperm Cells-half carry single X chromosome, half carry single Y chromosome  Who determines gender??? Mom or Dad?

4. Human Pedigrees Female Male Partner Brothers and Sisters

7. Genetic Disorders from single Gene Defects Dominant/Recessive

8. Autosomal Recessive Disorders  Albinism-lack of pigment in skin, hair, eyes  Cystic Fibrosis-excess mucus in lungs, digestive tract, liver (death in childhood)  Phenylketonuria (PKU)-phenylalanine buildup in tissues, lack of pigment, mental retardation  Tay-Sachs-lipid buildup in brain, mental deficiency and blindness (death in childhood)

9. Albinism Tay Sachs Cystic Fibrosis PKU

10. Autosomal Dominant Disorders  Achondroplasia-dwarfism  Huntington’s Disease-mental deterioration and uncontrolled movements (appears middle age)  Hypercholesterolemia-excess cholesterol in blood, leads to heart disease  Polydactylism-more than 5 digits

12. Autosomal Codominant Disorders  Sickle Cell Disease-sickle shaped red blood cells, damage tissues, oxygen deficit, cause fatigue, more prone to infections (malaria resistance)

13. Sex-Linked Genes  Genes located on the X or the Y sex chromosomes  Some X-Linked: MD, melanoma, colorblindness, hemophilia  Some Y-Linked: testis determining factor  Males only have 1 X chromosome  will express phenotype for an X-linked gene from 1 allele (either dominant or recessive)  Females have 2  so they can be dominant, carriers, or recessive.

14. X-Linked Recessive Disorders  Males only need to inherit 1 recessive allele to express the disorder  more common in males  Females need to inherit 2 recessive copies of gene to express disorder  Colorblindness-inability to distinguish certain colors  Hemophilia-abnormal blood clotting  excessive external/internal bleeding  Duchenne Muscular Dystrophy-progressive weakening and loss of skeletal muscle

15. Father (normal vision) Colorblind Normal vision Mother (carrier) Daughter (normal vision) Son (normal vision) Daughter (carrier) Son (colorblind) Male Female Figure 14-13 Colorblindness = carried only on the X chromosome (never the Y) What are the genotypes and phenotypes of the offspring according to gender?

16. Father (normal vision) Colorblind Normal vision Mother (carrier) Daughter (normal vision) Son (normal vision) Daughter (carrier) Son (colorblind) Male Female Figure 14-13 Colorblindness

17. Genetic Problem- Sex- Linked  A woman who is a carrier for hemophilia mates with a man who has hemophilia.  Identify the genotypic and phenotypic ratios ACCORDING TO GENDER for the offspring

18. Nondisjunction  Homologous chromosomes fail to separate in Anaphase I of Meiosis  Results in gametes with abnormal chromosome numbers  disorders

20. Genetic Disorders from Chromosomal Defects

21. Chromosomal Disorders  Down Syndrome-Trisomy 21 (3 copies of chromosome #21, instead of the normal 2); mild to severe mental retardation, birth defects  Turner’s Syndrome-female with only 1 X chromosome (genotype=XO); no sex organs  sterile  Klinefelter’s Syndrome-male with extra X chromosome (genotype=XXY); sterile