Chapter 11 Introduction to Genetics
Introduction
•The branch of science that is concerned with the ways in which inheritable information is transmitted to
offspring is known as __________
Introduction and Reminders
–___________: traits (characteristics) are passed down from the parent to the offspring.
–Sexual Reproduction: the fusion of ______
•Sex cells (gametes)
_______
__________ and _____ cells
–Chromosomes of each gamete contain the traits of the parent
(A) Gregor Mendel
An Austrian monk who performed a series of experiments with sweet peas (1856-1868)
Experimented on pea plants because he Knew:
Peas Self- Pollinated :___________________________?????
They have Single parent
Example of Selective (True/pure) Breeding
Fertilization occurred: fusion of sperm and eggs cells
Reproduced in _________ numbers in a short time
(A) Gregor Mendel
He wanted to see how: ___________________________________
Mendel proposed that certain traits were inherited as a result of the transmission of __________
__________
Mendel’s hereditary factors, called genes ,
(A) Gregor Mendel
Two genes (one from each parent) called alleles determine the trait of the offspring
Genes are the Chemical factors
Example~~ Gene for: Flower Color ~ ~
(B) Genes and Dominance
He studied Seven traits
-Trait: a specific characteristic, ex Height, color, shape
-Each trait had two contrasting Characteristics:
(B) Genes and Dominance
P  F1 (100% pure)  F2 He studied Seven traits his F2
numbers were staggering
Mendel's Three Major Concepts
1. _______________________________
2. _______________________________
3.___ Independent Assortment_______
1. Principle of Dominance: Also referred to as Law of Dominance
•States that the __________ allele will mask (cover) the recessive allele.
•( if the pair is ________)
•Tt = tall, since T is dominant for tallness
•The only time that the recessive allele is shown is when its homozygous recessive
•tt = short
2. Principle of Segregation : States that the alleles of an allelic pair will __________ and then
_______________ to form a new trait
•Ex:
Punnett square????
P
F1
Do Now:
1. Define the terms phenotype and genotype
2. Match the examples below in the appropriate box:
Blue eyes, tall, homozygous, hybrid, short, heterozygous
Phenotype
Definition
Examples
Terms:
Homozygous
Genotype
Heterozygous
11-2 Probability and Punnett squares
Chapter 27
Heredity
Intermediate
Inheritance
Mendelian
Incomplete
dominance
Codominance
Multiple
Alleles
Dominance
11-3 Intermediate Inheritance
•The hybrid offspring are _____________ different (look different) than their Homozygous parents.
• 6 types:
1. Incomplete Dominance
2. Co dominance
3. Multiple Alleles
4. Polygenic traits
5. Epistatic Genes, (Mask over other genes)
6. Sex linked genes
Incomplete dominance
•Think pink roses
•Both alleles are dominant
•Blending of traits
•F1 generation = pink roses.
•The roses will be pink due to a blending of traits
Co dominance
•Both alleles are __________
•Mixture of the 2 traits
•F1 generation = roan cattle.
•Cattle that is roan will have both
white hairs and red hairs on it (mixture)
•Red cow (RR)
•White cow (WW)
•Roan cow (RW)
Cross a Red cow (
) with a Roan cow (
)
Blood types are an example of Co dominance and Multiple Alleles
Co dominance
•In co dominance and incomplete dominance, the F2 generation is always
1:2:1
(V) Multiple Alleles
•No more than two alleles for a given trait may be present within each cell
•Ex: blood types
•A, B, AB, & O
Blood Types
Ex: A man with heterozygous blood type A marries a woman with blood type O. What are the
possibilities of blood types for the children