Chapter 27 Mendelian Genetics

Chapter 27 Mendelian Genetics

Chapter 11 Introduction to Genetics


•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????



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 / Genotype




11-2 Probability and Punnett squares

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


(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