1. Genetics
 Classic Genetics – Mendelian Genetics
 Principal of genetics
1. Dominance
2. The principal of independent assortment
3. The principal of segregation
 Examples:
color of flowers – red V.S. white
dominant trait V.S. recessive trait
complete dominance V.S. incomplete dominance
genotype V.S. phenotype
homozygous V.S. heterozygous
monohybrid V.S. dihybrid
gametes and zygotes
Punnett square

3. Gregor Mendel
Reference: http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBookgenintro.html

4. Crosses With Two Traits
Smooth seeds (S) are dominant over wrinkled (s)
seeds.
Yellow seed color (Y) is dominant over green (y).

5. 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 -- AB
Universal
donor

6. Human Genetics – Cont’d
Two 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 ?

7. 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

8. 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.

10. Male Karyotype
Female Karyotype

12. 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.

15. Genetic Diseases
1. Tay – Sachs Disease
2. Maple Syrup Urine Disease (MSUD)
3. Chemochromatosis
4. Cystic Fibrosis
5. Colon Cancer
6. Breast Cancer
7. Alzheimer’s Disease
8. Hemophilia
9. Muscular Dystrophy
10. Sickle Cell Anemia
11. Fragile X Syndrome
12. Turner Syndrome
13. Down Syndrome
14. Klinefelter Syndrome
15. XXY condition
16. Color Blindness

16. 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

17. 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)

18. Trisomy 18 *
Triploid Set of Chromosomes