1. Heredity and Genetics
Who do you look like?

2. Heredity - the passing of traits from parent to offspring
Genetics – the study of how traits are inherited
Genes
The material that controls which traits are expressed in an organism
Genes come in pairs and offspring inherit one copy of each gene from each parent

3. Alleles - the different forms of a trait that a gene may have
Where are genes found? Where are alleles found?

4. * Characteristic - a feature that has different forms
*Traits - the different forms of the characteristic
For Example:
head hair is a characteristic of humans
red hair or curly hair are traits
What are some other examples of characteristics and traits?

5. Trait Descriptions Dominant Trait-
a trait that prevents another trait from appearing.
dominant allele
covers up or dominates the other trait
capital letters
represent the dominant alleles

6. Recessive Trait
a trait that does not appear when the dominant trait is present
recessive allele
the trait that seems to disappear
lower case letters
represent the recessive alleles

7. How Alleles Combine *Hybrid
receives different genetic information for a trait from each parent.
It is a trait that is made up of a combination of a dominant and a recessive trait.
* Heterozygous (hybrid)
an organism with two different alleles for one trait (written Tt)
Hetero- means different.

8. * Pure
receives the same genetic information for a trait from each parent
It is a trait that is made of all dominant or all recessive traits.
*Homozygous (pure) Homo means- “same”
an organism with two alleles for one trait that are the same.
written T T for pure dominant or
tt for pure recessive

9. Genetic Make-up and Appearance
Genotype
the genetic make-up of an organism.
It is the combination of alleles that an organism gets from its parents. (example: Tt)
Phenotype
The way an organism looks as a result of its genotype
Physical appearance (example: blue eyes)

10. Punnett Squares
Geneticist Reginald Punnett developed a diagram that can be used to predict the way genes will combine when passed from parent to offspring.

11. Capital letters – dominant traits
Lower case letters – recessive traits
*letters always represent the dominant trait*
RR – indicates a pure dominant trait
rr – indicates a pure recessive trait
Rr – indicates a hybrid trait

12. Sample Punnett Square For Example: mice G dominant trait – gray coat
g recessive trait – white coat
Genotype Phenotype
GG – pure dominant gray
gg – pure recessive white
Gg – hybrid gray

13. Draw the Punnett Square Below
Traits: Genotype % Phenotype %
G= gray fur % pure dominant _____ % gray g = white fur ____%pure recessive _____% white
____% hybrid
Cross: Mom Dad
Gg x gg
Dad= Gg
Mom= gg

14. Applying the Heredity Laws
Law of Dominance
-Traits are inherited in pairs
- Both the dominant and recessive trait can
be present in the organism, but only the
dominant trait will appear