With your group on a piece of

paper answer the following

questions • What do you think of when you hear the word

“genetics”?

• What are 3 examples of a trait?

• If a red flower and white flower reproduces, what color will the offspring be? Why?

• Assign one person to scribe, and one person to share with the class the answer to a question.

From whom did you get your traits?

• Parents

• Mom

• Dad

What kind of traits do you think you

got from your parents?• Eye color

• Hair color

• Height

• Nose shape

Which traits do you prefer?

Which traits do you prefer?

“If you like it, then you should put a ring on

it”• If you could marry anyone in the world… who

would it be?

• Why?

What is the next chapter?

• A. Ecology

• B. Viruses

• C. Genetics

• D. Plants

10.1 Mendelian Genetics!

Pg. 177

What is genetics? • Genetics: • Study of heredity and variation in organisms.• Heredity: • Passing of genetic information from parent to

offspring.

Traits• Traits: • Variation of a particular character.

• Ex. Eye color, hair color, and nose shape.

What are some different traits?

• Tail length• Hair color • Ear direction

•

Mendelian Genetics • In the 1800s an Austrian monk studied plants.

His name was Gregor Mendel. He is called the “Father of Genetics”.

• Mendel wanted to describe how traits were passed between generations.

What happens when you cross red with

white?• Red mixed with white makes….

• Pink

• If you crossed a red flower and a white flower… what color would the offspring be?

• Red, white, or pink

Mendel’s Experiment• Performed experiments using pea plants.

• Why pea plants?• Easy to grow• Have easy observable traits• Reproduce quickly

Pea Plant Traits• 1. Flower color

• 2. Flower position

• 3. Seed color

• 4. Seed shape

• 5. Pod shape

• 6. Pod color

• 7. Plant height

Mendel’s Experiment• Step 1: • Looked at one trait, the flower color.

• Mendel allowed the pea plants to self-pollinate. This gave him purebred plants for the offspring.

• Purebred: Genetically uniform (identical).

• He called these plants the P generation (Parental).

Mendel’s Experiment• Step 2: • Cross-pollinated two P generation plants.

• Monohybrid cross: Parent plants differ in one characteristic.

• Flowers were all purple. He called these plants the F1 generation. F1 generation is the offspring of the P generation.

Mendel’s Experiment• Step 3:• Allowed F1 generation to self-pollinate.

• Produced a mix of white and purple flowers. He called this generation the F2 generation.

Mendel kept growing pea plants!

Overall

10.2 Inheritance Theory

• For each inherited characteristic an individual has 2 copies of a gene.

• These copies are called alleles.

• Alleles are represented by letters.

• Ex. PP or Pp or pp

Alleles• Dominant alleles: • Will always be expressed with 1 or 2 uppercase

letters.

• Ex. PP or Pp• Recessive alleles: • Will only be expressed with 2 lowercase letters.

• Ex. pp

Let’s Try• Ex. Flower color• Purple is dominant to white.

• What color is PP?• Purple

• What color is pp?• White

• What color is Pp?• Purple

Vocabulary• Homozygous: • When the alleles are the same.

• Homozygous Dominant:• Alleles are both uppercase letters. Ex. PP or BB

• Homozygous Recessive:• Alleles are both lowercase letters. Ex. pp or bb

• Heterozygous: • Different. One uppercase and one lowercase letter.

• Ex. Pp or Bb

Genotype/Phenotype• Genotype: • Genetic makeup of an organism. • Ex. PP or Pp or pp• Phenotype: • Physical characteristic expressed from the

genotype.• Ex. Purple, purple, white

Mendel's First Law• Law of Segregation:• Organism inherits two copies of genes, one from

each parent. Alleles are separated during gamete formation.

Punnett Squares• Diagram that shows the probabilities of the

possible outcome of a genetic cross.

 

Your mother is homozygous for black hair and

your dad has blonde hair. Black is dominant to blonde.

Testcross• What is the genotype of an organism that

displays the dominant phenotype?

• Let’s say purple flower color. And we use the allele P.

• PP or Pp

• How can we figure out if the organism is PP or Pp?

Perform a Testcross using Punnett Square

• What would the other organism’s genotype and phenotype be?

• Would have to use pp and white color flower.

Mendel's Second Law• Law of Independent Assortment: • Alleles for different genes separate independently

of one another during gamete formation.

• Dihybrid cross: • Crossing organisms differing in two

characteristics.

• Mendel crossed a true-breeding plant with round yellow seeds (RRYY) with a true-breeding plant grown from wrinkled green seeds (rryy)

• What would the offspring's phenotype be?

• All round and yellow.

• He then self pollinated the offspring.

10.3 Variations of Inheritance

• What is the offspring when you cross a Black chicken with a White chicken?

• x

• Blue chicken

• This is called intermediate inheritance or incomplete dominance.

• Intermediate inheritance:• Inheritance in which heterozygotes have an

intermediate phenotype. Neither phenotype is expressed in offspring.

P

F1

F2

RR x rr

Rr x Rr

1 RR

2 Rr

1 rr

Multiple Alleles• Codominance: • Both dominant alleles are expressed.

• For example blood. What are the four blood types?

• A• B• AB• O

ABO Blood AllelesIA – dominant allele for type A blood

IB – dominant allele for type B blood

i – recessive allele for type O blood

ABO Blood GroupingBlood type Genotype

A IAIA or IAi

B IBIB or IBi

AB IAIB

O ii

NOTE: Blood type AB is also an example of codominance

Polygenic Inheritance• Polygenic inheritance: • Multiple genes affect a characteristic, the

variation in phenotypes can become greater.

• Example.• Humans height and skin color.

Importance of Environment

• If a woman who is 6 ‘3’ and mates with a male who is 6 ‘7’… does that mean their son or daughter will be tall? Why?

• No, their offspring could be malnourished.

• Think of plants. Depending of the plant gets sunlight and water it affects how it will grow.

• Think of professional athletes and their parents.

Environment • Temperature can also effect the phenotype.

Siamese cats usually have white fur but when there is cooler temperatures it changes the cats enzyme which makes the coat color darker.

10.4 Meiosis Explains Mendel’s Principles

• Chromosomes theory of inheritance:• States that genes are located on chromosomes,

and the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns.

• All advanced organisms have chromosomes. Half the chromosomes comes from the father and half from the mother.

Genetic Linkage and Crossing Over

• When genes are located on separate chromosomes, they sort independently of each other.

• When genes are located close to each other the greater the genetic linkage.

• Genetic linkage: • The tendency for the alleles on one chromosome

to be inherited together.

10.5 Sex-linked traits• Humans have 23 pairs of chromosomes.

• One set of chromosomes are called sex chromosomes.

• If you are XX you are a female.

• XY you are a male.

Chromosomes

Sex Linked Genes• Any gene that is located on the sex chromosome

is called sex linked gene.

• In humans most sex linked genes are located on the X chromosome because it is much bigger than the Y chromosome.

Colorblindness• Colorblindness is inherited as sex linked X

recessive traits.

XB Xb

Xb XB Xb Xb Xb

Y XB Y Xb Y

WHAT NUMBERS DO YOU SEE?

WHAT NUMBERS DO YOU SEE?

WHAT NUMBERS DO YOU SEE?

NOW WHAT NUMBER DO YOU

SEE???

• What is the fastest way to determine the sex of a chromosome?

Pull down its GENES