1. Introduction to Heredity

2. What is Heredity?
Heredity is the passing of traits from parents to offspring
Genetics is the study of heredity

3. Gregor Mendel Known as the “Father of Genetics” Austrian Monk
Born in 1822

4. Mendel’s Work
Experimented with “True Breeding” pea plants in his garden
True Breeding
Plants that produce identical offspring when allowed to self pollinate
AKA “Purebred”
Discovered how traits are passed from parent to offspring in sexual reproduction

5. What is a Trait? A trait is a notable feature or quality in a person

6. Traits Inherited vs. Acquired
Received from biological parent
Eye color
Height
Blood Type
Acquired during lifetime; not inherited
Ability to ride a bike
Scars
Pierced ears
Some traits can be both!
Skin Color
Received genes for skin color from both parents
Amount of time in the sun affects skin color

7. Genes A gene is a unit of heredity
Occupies a specific location on a chromosome
Codes for or determines a specific trait
Most traits are not coded for by just one gene

8. Genes and Chromosomes Genes are located on chromosomes
Chromosomes come in pairs
Each pair is called a homolog
On each homolog are sites where specific genes are located

10. Alleles Alleles are various forms of the same gene. Example 1:
Gene: Eye Color
Alleles: Brown, Blue, Hazel
Example 2:
Gene: Seed Color
Alleles: Green, white, yellow

11. Mendel’s Work, continued
Mendel also performed experiments with hybrid plants
Hybrids - Plants that were produced by parents with different traits
In these experiments, he discovered that traits are inherited by parents passing alleles to their offspring

12. Mendel’s Conclusions (Principles of Heredity)
Individuals carry two alleles for each trait, but only pass down one to their offspring
One allele is dominant over another

13. Alleles determine traits
An organism’s traits are controlled by the alleles it inherits from its parents
Mendel discovered that there are two types of alleles:
Dominant
Recessive

14. Dominant Alleles
Dominant Allele: an allele whose trait is always shows up in the organism when the allele is present
Expressed if only one is present
Example: Brown Eye Color

15. Recessive Alleles
Recessive Allele: an allele whose trait is hidden whenever the dominant one is present
Can only be expressed if two are present
Example: Blue Eye Color

18. Alleles are represented by symbols
Dominant
Represented by a capital letter
Recessive
Represented by the lower case letter w W

19. Alleles interact to produce traitsW
Each parent contributes ONE allele for a given trait
The combination of alleles from parents can result in varying traits in their offspring
Alleles for widows peak
chromosomes w

20. Genetic Terminology
Genotype: An organisms genetic makeup, or alleles an organism has for a trait is its genotype
Ww, Bb, bb, ww, etc
Phenotype: An organism’s physical appearance, or visible traits is its phenotype.
Widow’s peak, brown eyes, blue eyes, straight hairline, etc

22. Alleles for flower color
Example: Flower Color
Genotype Pp
Alleles for flower color
Phenotype
Physical appearance

23. Genetic Terminology Terms used to describe an organisms genotype
Heterozygous – an organism that has two different alleles for a trait is said to be heterozygous
Example: Ww, Bb
Homozygous – An organism that has two identical alleles for a trait is said to be homozygous
Example: WW, ww, BB, bb

24. Using Genetic Terminology
Homozygous Recessive
Homozygous Dominant
Heterozygous

25. Using Genetic Terminology
Homozygous Recessive
Homozygous Dominant
Heterozygous

26. Using Genetic Terminology
Homozygous Recessive
Homozygous Dominant
Heterozygous

27. Using Genetic Terminology
Homozygous Recessive
Homozygous Dominant
Heterozygous

28. Using Genetic Terminology
Homozygous Recessive
Homozygous Dominant
Heterozygous

29. Can you determine an organism’s genotype just by looking at it?

30. Traits in a population
Observable characteristics we inherit from our parents
Some traits are common in a population, while others are not
Every person has a different overall combination of traits that make them unique