1. Mendel’s Principles Revisited
Organisms typically have ____copies of each gene, (one from each _______)
An organism’s _____ of genes (2 alleles) are segregated from each other when ________ are formed.
Alleles for different ______ usually segregate _____________ of one another. (through meiosis)
(Law of Independent Assortment)
two
parent
pair
gametes
genes
independently

2. Independent Assortment in Peas
__ Round yellow
__ Round green
__ Wrinkled yellow
__ Wrinkled green 9 3 3 1

3. There are many variations of inheritance patterns!
Intermediate Inheritance - Inheritance in which heterozygotes have phenotypes between the phenotypes of 2 homozygotes. Example - Red & White = Pink
(also called Inbetween or Incomplete Dominance)

4. Intermediate Inheritance = Incomplete Dominance
Cross of two purple flowers ____ X ____
What are gamete possibilities?
genotype ratio
1RR : 2RB : 1BB
phenotype ratio
1red : 2 purple : 1 blue
Can you have a heterozygous red or blue flower? ___ RB RB R B RR RB R
red
purple BB RB B
purple
blue no

5. Intermediate Inheritance
Chickens
C = Trait-Color
CB = Black
CW = White
What do we get
if we cross - Black x White
CBCB CWCW
CBCW CB CW
CBCW

7. Remember, the 1st generation of babies are called the F1 generation.
Neither black nor white are dominant. No capital or lower case letters are used
Parent Phenotypes can reappear in the F2 generation
Now, we’ll cross 2 of the babies…
CBCW X CBCW
25% - CBCB BLACK
50% - CB CW BLUE
25 % - CWCW WHITE CB CW
CBCB
CBCW
CWCW

8. Codominance
alleles
Both _______ contribute to the phenotype of the organism by showing up simultaneously (at the same time) in heterozygous
individuals.
In cattle and horses, if you cross a pure ____ (RR) with a pure ______ (WW), you get (RW) which produces the color _____.
red
white
roan

9. Another Example of codominance – Cow colorRR WW RW

10. Codominance
These cattle or horses actually have both red and white hairs intermixed, or are spotted. Roan is a third ___________.
If you cross a roan with a white…
phenotype R W RW WW W
roan
white RW WW W
roan
white

11. Multiple Alleles
In this pattern of inheritance, the genes have more than _____ alleles controlling them and are therefore said to have multiple alleles. No individual has more than _____ alleles, but there are more than _____ possible alleles in a population, so a ______ will be expressed in more than two forms.
two
two
two
trait

12. Multiple Alleles
Blood type in humans is an example of this inheritance pattern.
The ______ different blood groups:
A, B, O, and AB
Are produced by ______ different alleles:
A, B, and O
four
Phenotype
Genotype A
AA or AO B
BB or BO AB
AB only O
OO only
three

13. What is the universal donor? O
What is the universal receiver? AB

14. Polygenic Traits Traits controlled by two or more genes
Show a wide range of phenotypes
The phenotype is produced by the interaction of more than ________ of genes.
1 pair

15. Human examples: skin, eye and hair color
When multiple genes affect a character the variation in phenotype is great.
Polygenic Inheritance - Combined effect of 2 or more genes on a single characteristic. (not “either-ors”)
Example -Skin Color (Yes simplified)
A, B, C contributes on unit of color
The recessive a, b, c do not contribute any unit of color

18. Potential combinations of alleles for a character increase with the number of genes that affect one character.
Meaning - The more genes there are, the more possible combinations.
Think about it like this - the more $$$$ you have, the more possible ways there are to spend it!

19. Temperature & Sunlight!
Importance of environment
Sometimes, phenotypes can depend on the environment.
Example #1 - Trees & leaves
Year to year, the leaves change size, color and shape. What affects this?
Temperature & Sunlight!

20. Siamese cats and Himalayan rabbits
Himalayan rabbits normally are white as melanin is not produced at temperatures above 35 C. If one shaves hair from back and places ice pack on the shaven skin, black hair is produced.  The ears, tail, and feet are normally black because they have less hair and are cooler.