1. Review: Meiosis + Zygote Sperm Father’s Characteristics Egg
Chapter 10
Sexual Reproduction and Genetics
Review: Meiosis
Sperm
Father’s Characteristics +
Egg
Mother’s Characteristics
Zygote

2. Gregor Mendel’s Peas Genetics – the scientific study of heredity
Chapter 10
Sexual Reproduction and Genetics
Gregor Mendel’s Peas
Genetics – the scientific study of heredity
Gregor Mendel – a monk from Austria, and is known as the father of genetics
He did his most notable work with pea plants in his garden.
10.2 Mendelian Genetics

3. Mendel performed cross-pollination in pea plants.
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
The passing of traits to the next generation is called inheritance, or heredity.
Mendel performed cross-pollination in pea plants.
Mendel followed various traits in the pea plants he bred.
A trait is a characteristic such as hair or eye color, and height.

4. The parent generation is also known as the P generation.
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
The parent generation is also known as the P generation.

5. The second filial (F2) generation is the offspring from the F1 cross.
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
The offspring of this P cross are called the first filial (F1) generation.
The second filial (F2) generation is the offspring from the F1 cross.

6. Mendel studied seven different traits.
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Mendel studied seven different traits.
Seed or pea color – Yellow or Green
Flower color – Purple or White
Seed pod color – Yellow or Green

7. Mendel studied seven different traits.
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Mendel studied seven different traits.
Seed shape or texture – Round or Wrinkled
Seed pod shape – Inflated or Constricted
Stem length – Tall or Dwarf
Flower position – Axial or Terminal

8. Genes in Pairs Allele 10.2 Mendelian Genetics
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Genes in Pairs
Allele
An alternative form of a single gene passed from generation to generation
Expressed as a letter
(A or a, B or b, etc.)
Found on the same location of homologous chromosomes.

9. Example: AA or aa Example: Aa Dominance
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Dominance
An organism with two of the same alleles for a particular trait is homozygous.
Example: AA or aa
An organism with two different alleles for a particular trait is heterozygous.
Example: Aa

10. Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Dominance
A dominant trait needs only one copy of an allele to express its phenotype.
A recessive trait requires two copies of an allele to express its phenotype.

11. Genotype and Phenotype
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Genotype and Phenotype
An organism’s allele pairs are called its genotype.
The observable characteristic or outward expression of an allele pair is called the phenotype.

12. Seed or pea color – Yellow or Green
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Seed or pea color – Yellow or Green
Seed color Phenotype
Yellow or Green
Seed color Genotype
Yellow (YY or Yy)
Green (yy)

13. Seed or pea color – Yellow or Green
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Seed or pea color – Yellow or Green
Yellow is dominant to green!!
A dominant allele will mask
the expression of a
recessive allele.
You only need one dominant
allele to represent yellow.
Genotype
Yellow (YY or Yy)
Green (yy)
YY or Yy
Must have two yy.

14. Genotype and Phenotype?
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Genotype and Phenotype?
Yellow is dominant to green.

15. Genotype and Phenotype?
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Genotype and Phenotype?
Yellow is dominant to green.

16. 11-2 Probability and Punnett Squares
Chapter 10
Sexual Reproduction and Genetics
11-2 Probability and Punnett Squares
Genetics and Probability
How do geneticists use the principles of probability?
Probability – the likelihood that a particular event will occur
The principles of probability can be used to predict the outcomes of genetic crosses.
photo credit: W. Perry Conway/CORBIS

17. Chapter 10
Sexual Reproduction and Genetics
Punnett Squares
Punnett Squares – a tool used to determine the combinations from a genetic cross
Shows all possible combinations of gametes and likelihood each will occur

18. Setting up a Punnett Square
Chapter 10
Sexual Reproduction and Genetics
Setting up a Punnett Square
Draw the punnett square – size of your square depends on how many traits you are using (Ex. 1 trait = 4 boxes, 2 traits = 16 boxes)
Gametes produced by each parent are shown along the top and left side.
Possible gene combinations for the offspring appear in the four boxes.
The principles of probability can be used to predict the outcomes of genetic crosses. This Punnett square shows the probability of each possible outcome of a cross between hybrid tall (Tt) pea plants.

19. Chapter 10
Sexual Reproduction and Genetics
Mendel’s Experiment
Gametes from the F1 generation parents are used to get the offspring for the F2 generation.
Mendel only looked at one trait at a time in his first experiments
Monohybrid cross – a cross involving one trait

20. Probablility and Segregation
One fourth (1/4) of the F2 plants have two alleles for tallness (TT).
2/4 or 1/2 have one allele for tall (T), and one for short (t).
One fourth (1/4) of the F2 have two alleles for short (tt).
The principles of probability can be used to predict the outcomes of genetic crosses. This Punnett square shows the probability of each possible outcome of a cross between hybrid tall (Tt) pea plants.

21. Mendel’s Law of Segregation
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Mendel’s Law of Segregation
Two alleles for each trait separate during meiosis.
During fertilization, two alleles for that trait unite.
Heterozygous organisms are called hybrids.

22. Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Monohybrid Cross
A cross that involves hybrids for a single trait is called a monohybrid cross.

23. Dihybrids are heterozygous for both traits.
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Dihybrid Cross
The simultaneous inheritance of two or more traits in the same plant is a dihybrid cross.
Dihybrids are heterozygous for both traits.

24. Law of Independent Assortment
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Law of Independent Assortment
Random distribution of alleles occurs during gamete formation
Genes on separate chromosomes sort independently during meiosis.
Each allele combination is equally likely to occur.

25. Punnett Square—Dihybrid Cross
Chapter 10
Sexual Reproduction and Genetics
10.2 Mendelian Genetics
Punnett Square—Dihybrid Cross
Four types of alleles from the male gametes and four types of alleles from the female gametes can be produced.
The resulting phenotypic ratio is 9:3:3:1.

26. Polyploidy is the occurrence of one or more extra sets of all
Chapter 10
Sexual Reproduction and Genetics
10.3 Gene Linkage and Polyploidy
Polyploidy
Polyploidy is the occurrence of one or more extra
sets of all
chromosomes
in an organism.
A triploid organism, for instance, would be designated 3n,
which means that
it has three complete sets of chromosomes.