1. Genetics

2. Think about this…. “My parents have brown eyes, why are mine blue?”
“My brother is tall. Why am I short?”
“Why does my sister have blonde hair while mine is brown?”

3. Are these inherited traits?
Your eye color
Your hair color and texture
Your height

4. Are these inherited traits?
Your personality
Your musical, athletic, and artistic abilities

5. Gregor Mendel Born in 1822 in Austria
Studied the garden pea plant to determine genetics
Father of Genetics

6. Gregor Mendel
Heredity – the passing on of characteristics from parents to offspring
Characteristics that are inherited are called traits

7. Gregor Mendel
Mendel studied only 1 trait at a time to control the variable
The tall plants that he worked with had been tall for many generation and had always produced tall offspring
This is called true breeding

8. Mendel’s Monohybrid Crosses
Mono = one
A hybrid is the offspring of parents that have different forms of a trait
Such as tall and short

9. Mendel’s Monohybrid Crosses
P generation - parents
The F1 generation (hybrids) were all purple – self pollinated
F2 generation had a ratio of 3:1
3 purple
1 white
F stands for filial – son or daughter

10. The rule of dominance The dominant trait is the trait that is observed
The recessive trait is the trait that ‘disappears’
What trait is dominant?

11. The rule of dominance Which is dominant and which is recessive?
TT Tt tt
BB bb Bb
ww WW Ww
HH hh Hh

12. Phenotypes and Genotypes
The way an organism looks or behaves is called its phenotype

13. Phenotypes and Genotypes
The allele combination an organism contains is its genotype
represented as TT for tallness
Any plant that is tall has a genotype either TT of Tt

14. Homozygous Homo: same Two alleles for the trait are the same
(TT or tt)
Which ones
are homozygous?

15. Heterozygous Hetero = different
Two alleles differ from one another (Tt)

16. Monohybrid crosses A a AA Aa aa Aa x Aa A: White fur a: Brown fur
a cross that shows the possible offspring for one trait
Punnett Square
Aa x Aa A a AA Aa aa
A: White fur
a: Brown fur
Genotypic Ratio: 1:2:1
Phenotype: 3 white:1 brown

17. Practice!
Cross a HOMOZYGOUS dominant female rabbit with a HETEROZYGOUS male rabbit using the same trait.
A: White fur
a: Brown Fur A a
What is the genotypic ratio?
After this slide you should do the Genetics Overview and Genetics Problems #1.
What is the phenotypic ratio?

18. Practice!
Cross a HOMOZYGOUS dominant female rabbit with a HETEROZYGOUS male rabbit using the same trait. A a
What is the genotypic ratio? AA AA
2 = AA
2 = Aa
2:2 or 50%
After this slide you should do the Genetics Overview and Genetics Problems #1.
What is the phenotypic ratio? Aa Aa
4 white fur

19. Practice!! Cross a female (Tt) with a male (Tt) using the traits:
T: tall
t: short T t T t

20. Practice!!
Cross a female (Tt) with a male (Tt) using the traits:
T: tall
t: short T t
T T Tt tt T t

21. Now its time for more practice…

22. Dihybrid crosses
two traits calculated :RrYy x RrYy

23. Dihybrid Crosses: a cross that shows the possible offspring for two traits
BbRr x BbRr BR bR br Br
BBRR
BbRR
BbRr
BBRr
BBrr
Bbrr
bbRR
bbRr
bbrr
Fur Color: B: Black b: White
Coat Texture: R: Rough r: Smooth
BbRr x BbRr
Phenotypic Ratio: :3:3:1

24. More Complex Patterns of Heredity
Codominance/ Incomplete dominance
Multiple Alleles
Sex-Linked Traits

25. Codominance: two dominant alleles are expressed at the same time
CRCR
CWCW
CRCW

26. Codominance Sickle-Cell Anemia is another codominant trait. NSNA NSNA
NA=Normal RBC
NANA
NANA
NS=Sickle Cell RBC NA

27. Multiple Alleles: traits with more than 2 alleles
Blood type has 3 alleles: A, B, O
A and B are codominant over O
O is recessive
Phenotype
Genotype
Can Receive From
Can Donate To A
AA, AO
A, O
A, AB B
BB, BO
B, O
B, AB AB
A, B, AB,O O OO
A, B, AB, O

28. What are Sex-Linked Traits?
Traits that are located on one of the sex chromosomes (XY)
Hemophilia: Failure of blood to clot
Alix and Nicholas II
Muscular Dystrophy: wasting away of muscles

29. Can I inherit a sex-linked disease?
Mothers (XX) can pass disorders to both sons (XY) and daughters (XX)
Fathers (XY) can only pass disorders to daughters (XX)
In humans, the term sex-linked traits usually refers to X-linked traits.
The human X-chromosome is much larger than the Y. Thus, there are more X-linked than Y-linked traits.
Most X-linked genes have no homologous loci on the Y chromosome.
Most genes on the Y chromosome not only have no X counterparts, but they encode traits found only in males (e.g. testis- determining factor).
Examples of sex-linked traits in humans are color blindness and hemophilia. Fathers pass X-linked alleles to only and all of their daughters.
Males receive their X chromosome only from their mothers.
Fathers cannot, therefore, pass sex-linked traits to their sons.
Mothers can pass sex-linked alleles to both sons and daughters.
Females receive two X-chromosomes, one from each parent.
Mothers pass on one X-chromosome (either the maternal or paternal homologue) to every daughter and son.
Most disorders are carried on the X chromosome, so males are more likely to inherit them.

30. How can I tell if I have a genetic disorder?
Karyotypes are a “map” of all 46 (23 pair) of chromosomes.

31. What’s wrong with this Karyotype?
Is this a male or a female?

32. What’s wrong with this Karyotype?
Is this a male or a female?

33. Down Syndrome
Down syndrome occurs because of the presence of an extra 21st chromosome.
Down syndrome is also called trisomy 21
Physical Traits
Short stature. A child often grows slowly and, as an adult, is shorter than average.
A short, wide neck with excess fat and skin
Small, low-set ears.

34. Klinefelter Syndrome chromosome abnormality that affects only men
born with at least one extra X chromosome.
The male with Klinefelter Syndrome will be born with 47 chromosomes in each cell, rather than the normal number of 46.
Klinefelter Syndrome is also called 47 X-X-Y syndrome.
An infant with Kleinnfelter's Syndrome appears normal at birth, but the defect usually becomes apparent in puberty when secondary sexual characteristics fail to develop, and testicular changes occur that eventually result in infertility in the majority of those affected.

35. Patau syndrome Trisomy 13
Most cases of Patau syndrome are not inherited, but occur as random events during the formation of reproductive cells (eggs and sperm).
Symptoms:
Mental & motor challenged
polydactyly (extra digits)
Heart defects
Cleft palate
Spinal defects