2. Genetics Cells contain a nucleus Nucleus contains paired chromosomes
Chromosomes contain genes
Gene is a section of DNA
DNA contains an organism’s information code
to make a specific protein
Proteins are needed for growth
and repair of cells

3. What have you inherited?
Heredity is the passing of traits from parent to offspring
What controls these traits?
Traits are controlled by genes

4. Heredity

5. Tell me what I am ?????

6. Sex Determination

7. Sex Determination
Female can contribute only a X chromosome towards the sex of their offspring.
Male can contribute an X or a Y chromosome toward the sex of their offspring.
Absence of an Y chromosome results in a the embryo developing into a female.
Presence of an Y chromosome results in the embryo developing into a male.

9. Gregor Mendel Austrian Monk Considered the “Father of Heredity”
He conducted pea plant breeding experiments in their monastery garden.
In 1865 he made his work public, units of inheritance.

10. Mendel’s First Experiment
Mendel crossed pure tall
Pea plants with pure short
Pea plants.
Tall X Short 
What do you predict
Happened?

11. All the Offspring Plants were Tall!
How can you explain this?
One trait is dominant over the other or covers it up.
The other trait is said to be recessive.

12. Does the recessive trait disappear?
To test if the recessive trait was still there Mendel allowed the offspring from the first cross to self pollinate.
Tall offspring X Tall offspring 
What do you think happened?

13. The short trait reappeared!
Not only did it reappear, but it was always in a three to one (3:1) ratio
Three tall to every one short.
Why was this so predictable?

14. Mathematical Probability
Lets apply letters to represent the traits
T = tall
t = short
How many letters does the offspring get from its parents?
2! One from mom and one from dad

15. Homozygous Tall x Homozygous Short
Punnett Square
Tall vs. Short
Homozygous Tall x Homozygous Short
T T x t t
Tall is Dominant over Short
Tall allele = T
Short allele = t T T t T t T t
All Tt
All Tall t T t T t

16. T t T T T t T t T t t t Punnett Square
Tall vs. Short
Heterozygous Tall x Heterozygous Tall
T t x T t
Tall is Dominant over Short
The Short trait only appears when pure-
Because it is Recessive
Tall allele = T
Short allele = t T t T T T t T
1TT:2Tt:1tt (genotype)
3 Tall: 1 Short (phenotype) t T t t t

17. DO NOW What determines if the offspring will be a male or female?
23 pair of chromosomes
What are the chromosomes for a girl?
Boy?
XX girl XY boy

18. How many alleles does the offspring receive for each trait?
TWO! One from mom and one from dad.
You can get same allele from each parent:
Homozygous  Pure, two of the same alleles from each parent
OR two different alleles:
Heterozygous  Hybrid, two different alleles from each parent.

19. More terms…
The alleles received from each parent is called the genotype
What is expressed (shows up) is called the phenotype
Ex: TT is the genotype
Tall is the phenotype

20. Homozygous Tall x Heterozygous Tall
Punnett Square
Tall vs. Short
Homozygous Tall x Heterozygous Tall
T T x T t
Tall is Dominant over Short
Tall allele = T
Short allele = t T T T T T T T
2TT:2Tt
All Tall t T t T t

21. Homozygous Short x Heterozygous Tall
Punnett Square
Tall vs. Short
Homozygous Short x Heterozygous Tall
t t x T t
Tall is Dominant over Short
Tall allele = T
Short allele = t t t T t T t T
2Tt:2tt
2 Tall: 2 Short t t t t t

22. Homozygous Tall x Homozygous Tall
Punnett Square
Tall vs. Short
Homozygous Tall x Homozygous Tall
T T x T T
Tall is Dominant over Short
Tall allele = T
Short allele = t T T T T T T T
All TT
All Tall T T T T T

23. Homozygous Short x Homozygous Short
Punnett Square
Tall vs. Short
Homozygous Short x Homozygous Short
t t x t t
Tall is Dominant over Short
Tall allele = T
Short allele = t t t t t t t t
All tt
All Short t t t t t

24. Dominant
Dominant
Dominant
Dominant
Dominant
Dominant
Dominant

25. Homozygous Green x Homozygous Yellow
Punnett Square
Green Pea Pod vs. Yellow Pea Pod
Homozygous Green x Homozygous Yellow
G G x g g
Green is Dominant over Yellow
Green allele = G
Yellow allele = g G G g G g G g
All Gg
All Green g G g G g

26. Homozygous Green x Heterozygous Green
Punnett Square
Green Pea Pod vs. Yellow Pea Pod
Homozygous Green x Heterozygous Green
G G x G g
Green is Dominant over Yellow
Green allele = G
Yellow allele = g G G G G G G G
2 GG: 2Gg
All Green g G g G g

27. Heterozygous Green x Heterozygous Green
Punnett Square
Green Pea Pod vs. Yellow Pea Pod
Heterozygous Green x Heterozygous Green
G g x G g
Green is Dominant over Yellow
Green allele = G
Yellow allele = g G g G G G g G
1 GG: 2Gg: 1gg
3 Green: 1 Yellow g G g g g

28. Homozygous Yellow x Heterozygous Green
Punnett Square
Green Pea Pod vs. Yellow Pea Pod
Homozygous Yellow x Heterozygous Green
g g x G g
Green is Dominant over Yellow
Green allele = G
Yellow allele = g g g G g G g G
2 Gg: 2 gg
2 Green: 2 Yellow g g g g g

29. Practice Quiz Mendel

30. Practice quiz probability

31. What is a pedigree chart?
Pedigree charts show a record of the family of an individual
They can be used to study the transmission of a hereditary condition
They are particularly useful when there are large families and a good family record over several generations.

32. Symbols used in pedigree charts
A marriage with five children, two daughters and three sons. The eldest son is affected by the condition.
Eldest child  Youngest child
Normal male
Affected male
Normal female
Affected female
Marriage

33. Example of Pedigree Charts
Dominant or Recessive?
Is this pedigree dominant or recessive?

34. Answer
Dominant
It is dominant because a parent in every generation have the disorder. Remember if a parent in every generation has the disorder, the disorder has not skipped a generation. If the disorder has not skipped a generation the disorder is dominant.

35. Example of Pedigree Charts
Dominant or Recessive?
Is this pedigree dominant or recessive?

36. Answer
Recessive
It is recessive because a parent in every generation does not have the disorder. Remember the disorder can skipped a generation if the disorder is recessive. The parents can be heterozygous and be carriers of the disorder but not have the symptoms of the disorder.

37. Pedigree Chart