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Genetics Classic Genetics – Mendelian Genetics Principal of genetics
1. Dominance2. The principal of independent assortment3. The principal of segregation
Examples: color of flowers – red V.S. white
dominant trait V.S. recessive traitcomplete dominance V.S. incomplete dominancegenotype V.S. phenotypehomozygous V.S. heterozygousmonohybrid V.S. dihybridgametes and zygotesPunnett square
Gregor Mendel
Reference: http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookgenintro.html
Crosses With Two TraitsSmooth seeds (S) are dominant over wrinkled (s)
seeds.Yellow seed color (Y) is dominant over green (y).
Human Genetics Single trait genetic inheritance –
blood type A B O Blood type A, B are dominant versus O. A and B are co-dominant.
Blood type
Phenotype Genotype Antigen Antibody
A A AA, AO A B
B B BB, BO B A
AB AB AB AB --Universal recipient
O O OO -- ABUniversal
donor
Human Genetics – Cont’dTwo traits genetic inheritance –
TONGUE ROLLING (T)TONGUE ROLLING (T) V.S. non-rolling (t)non-rolling (t)
WIDOW’S PEAK (W)WIDOW’S PEAK (W) V.S. straight hairline (w)straight hairline (w)
Parents (P): TTWW x ttww
gametes: TW tw
F1 TtWw
Heterozygous cross: TtWw x TtWw
gametes: TW Tw tW tw TW Tw tW tw
F2 ?
Punnett square – dihybrid cross
Phenotype ratio --- 9:3:3:1
TW Tw tW tw
TW TTWW TTWw TtWW TtWw
Tw TTWw TTww TtWw Ttww
tW TtWW TtWw ttWW ttWw
tw TtWw Ttww ttWw ttww
Human chromosomes All but one pair of chromosomes are the
same in both males and females. They are designated autosomes. The remaining pair of chromosomes are sex chromosomes.
Human cells have a diploid chromosome number of 46. The nucleus contains 22 pairs of autosomes and 1 pair of sex chromosomes (X and Y).
Each chromosome in this karyotype is duplicated and so consists of two sister chromatids.
Male Karyotype
Female Karyotype
Or
Sex Chromosomes XY Male XX Female
Karyotype
The photos of chromosomes are arranged in order of size and numbered.Chromosomes 23 are the sex chromosomes.
Genetic Diseases1. Tay – Sachs Disease2. Maple Syrup Urine Disease (MSUD)3. Chemochromatosis4. Cystic Fibrosis5. Colon Cancer6. Breast Cancer7. Alzheimer’s Disease8. Hemophilia9. Muscular Dystrophy10. Sickle Cell Anemia11. Fragile X Syndrome12. Turner Syndrome13. Down Syndrome14. Klinefelter Syndrome15. XXY condition16. Color Blindness
Sex Linkage
Morgan – the color of eyes in fruit fly. The sex linkage traits are usually on the
X chromosome. Sex-linked diseases:
1. Color Blindness
2. Duplchenne Muscular Dystrophy
3. Hemophilia
Color blindness genetic inheritance Muscular dystrophy genetic inheritance
Abnormal Number of Chromosomes
Eduwards Syndrome (Trisomy 18) Down’s Syndrome (Trisomy 21) Pata Syndrome (Trisomy 13) Turner Sundrome (Monosomy X) Klinefelter Syndrome (XXY) Crime Syndrome (XYY)
Trisomy 18 *
Triploid Set of Chromosomes