1. Today’s Agenda 2-6 Bellringer: What is a trait? Get your clickers!
Notes on Genetics
Homework: Worksheet

2. Genetics Part I
Study Pack #8

3. Today’s Goal…
I can explain how traits are inherited.

4. Let’s see what you know…
True or False
All traits are inherited
An allele is one form of a gene
If an allele is recessive the trait will always show up
If an organism is homozygous for a trait it has two alleles that are different

5. Traits Characteristics of an organism
Learned traits are a result of experiences and the environment
Examples: learning how to play an instrument or not touching a hot stove
Inherited traits are passed from parent to offspring in reproduction
Examples: infants have 10 fingers and 10 toes and breath as soon as they are born

6. Heredity Heredity is the passing of traits from parent to offspring
Genetics is the study of heredity
An organism is a collection of traits inherited from its parents
Traits are passed on through genes on chromosomes

7. Allele An allele is one form of a gene You have two for every trait
During meiosis alleles separate into different sex cells

8. Allele
During fertilization, each parent donates one chromosome from each pair
This results in two alleles for each trait
Page 307

9. Dominant and Recessive Alleles
The trait you end up with depends on your combination of alleles and which are dominant and recessive

10. Dominant and Recessive Alleles
A dominant allele is one whose trait always shows up in the organism when the allele is present

11. Dominant and Recessive Alleles
A recessive allele is covered up, whenever the dominant allele is present
Will only show up if the organism does not have the dominant allele

12. Dominant and Recessive Alleles
Dominant alleles are written with a capital letter
Recessive alleles are written with a lower case letter

13. Homozygous and Heterozygous Traits
An organism with two alleles that are the same is homozygous
Two dominant alleles
Two recessive alleles
An organism that has two different alleles is heterozygous

14. Let’s see what you know…
True or False
All traits are inherited
An allele is one form of a gene
If an allele is recessive the trait will always show up
If an organism is homozygous for a trait it has two alleles that are different