1. Introduction to Genetics
Chapter 11
Introduction to Genetics

2. Golden Doodle Blending Theory - offspring are a straight mix
A Brief History
In the past, people did not understand how traits were inherited, but there were many guesses based on things that could be observed.
Two theories emerged….
Blending Theory - offspring are a straight mix
Particulate Theory
traits are inherited as "particles", offspring receive a "piece" from each parent, some pieces may hide the others
Golden Doodle

3. Who was Gregor Mendel? GENETICS – study of heredity
He was known as the “FATHER OF GENETICS”
He discovered how traits were inherited
GENETICS – study of heredity
HEREDITY – the passing of traits from parents to offspring

4. Mendel’s Peas Mendel did his study on pea plants
which have many traits
tall/short
purple /white flowers
round/wrinkled seed

5. Genes and alleles Genes – sequence of DNA that determines a trait
Alleles – one of a number of different forms of a gene

6. self-fertilized or cross-fertilized
Pea plants can be
self-fertilized or cross-fertilized
(drawing)
During sexual reproduction, male and female reproductive cells join in a process known as fertilization to produce a new cell. Plants can self pollinate so they have only one parent.

7. True-Breeding Plants
always create plants that look like themselves (homozygous)
Hybrids
offspring of true-breeding plants (heterozygous)
Tall x Short = Hybrid

8. Some traits are dominant over others.
Tall x Short = all tall offspring (hybrids)
*Tall is the dominant trait
* Short is recessive

9. Mendel discovered that each trait is controlled by two factors (alleles)
Genes – factors that determine your traits
Genes are located on chromosomes

10. 1. The “Father of Genetics” is ____________
Quick Check - What do we know so far?
1. The “Father of Genetics” is ____________
2. Genetics is the study of _____________, which is how traits are passed from _________ to ____________
3. Mendel studied what organism? ____________
4. If one trait covers up another one, we say that it is ______________, the one that is covered up is ______
5. A “true-breeding” plant is one that can only produce plants like itself a) true b) false
6. If a tall and a short plant are crossed, it will create a
a) zygote b) gene c) hybrid

11. 1. The “Father of Genetics” is Gregor Mendel
Quick Check - What do we know so far?
1. The “Father of Genetics” is Gregor Mendel
2. Genetics is the study of Heredity, which is how traits are passed from parents to offspring
3. Mendel studied what organism? pea plants
4. If one trait covers up another one, we say that it is dominant the one that is covered up is recessive
5. A “true-breeding” plant is one that can only produce plants like itself a) true b) false
6. If a tall and a short plant are crossed, it will create a
a) zygote b) gene c) hybrid

12. GENOTYPE  -  what genes, letters, the organism has (TT, Tt, tt)
PHENOTYPE   - what it looks like (tall or short)

13. Mendel’s Experiments

14. Tracking Hybridization
Parent – P generation
Hybrid Offspring – F1 Generation
Hybrid Cross – F2 Generation

15. Explaining the Cross
When a parent makes sperm or eggs, their genes separate         (PRINCIPLE OF SEGREGATION)
The GAMETES (egg or sperm) contain either a T allele (tall) or a t allele (short)

17. Punnett Square t Tt Tt Tt Tt
Parents = TT and tt  F1 Generation – all tall
T T t Tt Tt Tt Tt

18. Punnett Square
F1 cross  F2 Generation: 3:1 ratio
T t T t TT Tt Tt tt

19. The law of Independent Assortment
How do alleles segregate when more than one gene is involved?
Mendel had discovered the principle of independent assortment. The principle of independent assortment states that genes for different traits can segregate independently during gamete formation. Mendel’s experiment is known as a two-factor, or dihybrid, cross.

20. Summary of Mendel’s Ideas:
The inheritance of biological characteristics is determined by individual units called genes, which are passed from parents to offspring.

21. Summary of Mendel’s Ideas:
2. Where two or more forms (alleles) of the genes for a single trait exist, some alleles may be dominant and others may be recessive.

22. Summary of Mendel’s Ideas:
3. In most sexually reproducing organisms, each adult has 2 copies of each gene - one from each parent. These genes segregate from each other when gametes are formed.

23. Summary of Mendel’s Ideas:
4. Law of Segregation: Alleles for different genes usually segregate independently of each other.

24. 7. Genes are located on _______________ 8. Every gene is made of two
Check for understanding
7.  Genes are located on _______________
8.  Every gene is made of two
a. genotypes b. alleles c. cells
9. The organism’s outward appearance, such as wrinkled seeds are referred to as the a) phenotype b) genotype

25. 10. The letters (ex. RR) that represent the traits are referred to as the a) phenotype b) genotype
11. An organism that has two different alleles, or letters, such as Rr is: a) homozygous b) heterozygous
12. An organism that has two of the same alleles, or letters, such as RR is: a) homozygous b) heterozygous
13. Which of the following sets would represent Mendel’s Parent (P) generation?
a) RR x RR b) Rr x Rr c) RR x rr
14. When two different alleles occur together, such as R r, the one that is expressed is a) dominant b) recessive

26. 7. Genes are located on chromosomes 8. Every gene is made of two
Check for understanding
7.  Genes are located on chromosomes
8.  Every gene is made of two
a. genotypes b. alleles c. cells
9. The organism’s outward appearance, such as wrinkled seeds are referred to as the a) phenotype b) genotype

27. 10. The letters (ex. RR) that represent the traits are referred to as the a) phenotype b) genotype
11. An organism that has two different alleles, or letters, such as Rr is: a) homozygous b) heterozygous
An organism that has two of the same alleles, or letters, such as RR is: a) homozygous b) heterozygous
13. Which of the following sets would represent Mendel’s Parent (P) generation?
a) RR x RR b) Rr x Rr c) RR x rr
14. When two different alleles occur together, such as R r, the one that is expressed is a) dominant b) recessive

28. What does this letter actually represent?
11. What is the diagram shown below called?
What does this letter actually represent?

29. Check for understanding
1.  A one-eyed purple people eater is crossed with a two eyed purple people eater.  All of their offspring have two eyes.   Which trait is dominant?

30. 2. If you use the letter E for this gene
2.  If you use the letter E for this gene.   What is the genotype of the offspring if the parents were EE x ee
    
3.  If you crossed the offspring with each other?  How many of the new offspring would you expect to have two eyes?
EE = two eyes
Ee = two eyes
ee = one eye