1. Warm Up
With your partner, define genotype and phenotype.

2. Predicting Genetic Outcomes
TEK 6B:
Predict possible outcomes of various genetic combinations such as monohybrid crosses, di hybrid crosses, and non Mendelian inheritance.
Trait – A particular characteristic that can vary from one individual to another. Ex: hair color
Alleles - Different forms of one gene
Ex: Brown, red, or blond hair are all different forms the hair color gene

3. Rule of Dominance
Dominant gene: Always expressed if present for a trait
Represented by a capital letter; “B” is for brown eyes. A brown-eyed organism could be BB or Bb to be dominant. The B for Brown eyes overpowers the b for blue eyes and so the organism displays the Brown eye trait.
Recessive gene: Only expressed if two alleles are present for that trait
Represented by a lowercase letter. “b” is for blue eyes. Organism must have genes bb to have blue eyes.

4. Homozygous vs. Heterozygous
Homozygous: Organisms have 2 identical (same) alleles for a trait
BB is homozygous dominant for brown eyes
bb is homozygous recessive for blue eyes
Heterozygous: Organisms have 2 (different) alleles for a trait
Bb is heterozygous for brown eyes

5. Phenotypes and Genotypes
Genotype: (genes) the genetic makeup or combination of 2 alleles
(1 from mom & 1 from dad)
Ex. BB, Bb, bb
Phenotype: physical characteristics of the trait
Ex. Brown hair, blue eyes (what you see)
Genotype - always use the letter of the dominant trait first.
Ex. Straight hair is dominant to curly hair
Straight hair is dominant = capitol S
Curly hair is recessive = lowercase s
Genotype for straight hair = SS or Ss
Genotype for curly hair = ss

6. Monohybrid Dihybrid Cross involving two traits.
Mendelian Genetics
Monohybrid Dihybrid
Cross involving two traits.
Cross involving a single trait.
Bb x Bb
RrYy X RrYy
Phenotypic Ratio: 3 purple : 1 white
Genotypic Ratio: 1BB : 2Bb : 1bb

7. Incomplete Dominance Codominance
Non Mendelian Genetics
Incomplete Dominance Codominance
The trait does not have a completely dominant allele, and a cross between organisms with two different phenotypes results in a third phenotype.
Heterozygous offspring display a third phenotype that is a
blending of the parental traits
Ex: Red (RR) x White (WW)
Offspring: Pink (RW)
The trait does not have only one dominant allele, but has two or more dominant alleles. When both are present, the individual displays both traits at the same time.
Parents: Red (RR) x Blue (BB)
Heterozygous Offspring: RB – red and blue striped

8. Multiple Alleles Non Mendelian Genetics
There are four different phenotype blood groups:
A, B, O, & AB
They are produced by three different alleles: A, B, and O
Which ones are
homozygous?
heterozygous?
Phenotype
All Genotypes Possible
Type A (Dominant)
IAIA (AA), IAi (AO)
Type B (Dominant)
IBIB (BB), IBi (BO)
Type AB (Codominant)
IAIB (AB)
Type O
(recessive)
ii (OO)

9. Sex- Linked Traits Non Mendelian Genetics Inheriting sex-linked traits
Genes located on the sex chromosomes are called sex-linked traits
Because the Y chromosome is small it carries few genes, along with the male determinant sex gene.
Ex. A woman who is heterozygous (a carrier) for hemophilia marries a normal man:

10. Folder Activity
You will complete the activities in the folder with your partner.
You should be using this opportunity to discuss the information and teach each other.
After you finish the folder activity you will take a QR quiz over the information.

11. QR Quiz