DO NOW: Quietly……..

Take a poll of how many of you have the following traits:

- brown hair -blonde hair -red hair- black hair - blue/green eyes-brown eyes

GENETICS

MAIN IDEA…………

ALIEN ACTIVITY

http://www2.edc.org/weblabs/BabyBoom/babyBoom.html

WHAT IS GENETICS???

Genetics is the scientific study of

heredity.

Heredity is what makes each species

unique.

KEY VOCABULARY Dominant:

inherited characteristic that appear in an organism

Represented with capital letter.Ex: B, X, R

Recessive:

inherited characteristics often masked

Represented with lowercase letter.Ex: b, x, r

KEY VOCABULARY

EXAMPLE:

Brown Eyes: B Blue Eyes: b

Dominant Recessive

Phenotype: physical traits that appear in an individual as a result of its genetic make-up

How to remember…….Phenotype= Physical

Ex: brown eyes, blonde hair

Genotype:

genetic Make Up of an individual

How to remember….GENotype= GENEtic

Ex:B- brown eyesb- blue eyes

having two identical alleles

Ex: BB or bb

having two different alleles for a trait

Ex: Bb

Homozygous Heterozygous

PHENOTYPE VS. GENOTYPE

bb Blue Eyes

Genotype Phenotype

A little girl has blue eyes

Allele different forms of a gene for a

specific trait 2 for each trait

ALLELE

Could code for a PURPLE flower

Could code for a WHITE flower

CHROMOSOME FOR FLOWER COLOR

MAIN IDEA…………

HISTORY

FATHER OF GENETICS: MENDEL

GREGOR MENDELAustrian MonkFamous for his work with pea plantsWHY?????

They weren’t messy Rapid results Many generation

He is known as the father of genetics

MENDEL’S WORK

Mendel used true-breeding plants True Breeding:

When bred with themselves they would produce identical offsprings.

He studied 7 different traits in pea plants.

Trait: is a specific characteristic that

can vary from one individual to another

MORE ON MENDEL’S WORK

Hybrids are offspring from parents with

different traits.

Genes are the chemical factors that

determine a trait.

MENDEL’S EXPERIMENTS: 3 PRINCIPLES

1. Principle of Dominance2. Segregation 3. Independent Assortment

PRINCIPLE 1: THE PRINCIPLE OF DOMINANCE

States that some alleles are dominant and others are recessive.

Dominant alleles are always expressed.

Recessive alleles are only expressed if both alleles are recessive.

PRINCIPLE 2: SEGREGATION

The two alleles for a trait separateHELP……

Segregate means to separate

Happens during meiosis

form gametes (sex cells)

PRINCIPLE 3: INDEPENDENT ASSORTMENT

states that genes for different traits separate independently during the formation of gametes.

EX:the color of the flower has

nothing to do with the lengthThey separate INDEPENDENTLY

SUMMARIZE MENDEL’S PRINCIPLES The inheritance of biological characteristics

are determined by genes.

For two or more forms of a gene, dominance and recessive forms may exist (Principle #1).

Most sexually reproductive organisms have two sets of genes that separate during gamete formation (Principle #2).

Alleles segregate independently (Principle #3).

MAIN IDEA…………

PROBABILITY AND PUNNETT SQUARES

PROBABILITY & GENETICS

Probability is the likelihood that an event

will happen.

The principle of probability can be used to predict the outcomes of genetic crosses.

PUNNETT SQUARESDiagram used to predict genetic

crosses.

REVIEW: Homozygous individuals with

identical allelesHeterozygous individuals with

different alleles are calledPhenotype physical characteristicGenotype genetic makeup

HOW TO USE PUNNETT SQUARES……

1. Choose a letter to represent the alleles in the cross.

2. Write the genotypes of the parents.3. Enter the possible gamete at the top and

side of the Punnett square.4. Complete the Punnett square by writing

the alleles from the gametes in the appropriate boxes.

5. Determine the phenotypes of the offspring.

6. Using the results of step 4. write down the genotypic and phenotypic ratios.

EXAMPLE PUNNETT SQUARE

WHAT IS THE PROBABILITY THAT TWO HETEROZYGOUS PURPLE FLOWERS WILL PRODUCE A WHITE FLOWER? 1. Choose a letter to represent the

alleles in the cross.

2. Write the genotypes of the parents.

3. Enter the possible gamete at the top and side of the Punnett square.

WHAT IS THE PROBABILITY THAT TWO HETEROZYGOUS PURPLE FLOWERS WILL PRODUCE A WHITE FLOWER?

4. Complete the Punnett square by writing the alleles from the gametes in the appropriate boxes.

5. Determine the phenotypes of the offspring.

6. Using the results of step 4. write down the genotypic and phenotypic ratios

REVIEW QUIZ ON PROBABLITY AND PUNNETT SQUARES

http://anthro.palomar.edu/mendel/quizzes/mendqui2.htm

MAIN IDEA…………

TEST CROSSES

WHAT IS A TEST CROSS?????

Test that is conducted to determine if the genotype of an organism HOMOZYGOUS

DOMINANT for a trait

HETEROZYGOUS for a trait

5 KEY POINTS……

1. The organism with the dominant trait is always crossed with an organism that is HOMOZYGOUS RECESSIVE

2. If ANY offspring shows the recessive trait than the unknown genotype is heterozygous.

1. Recessive trait seen heterozygous

3. If ALL offspring have the dominant trait, the unknown is homozygous dominant.

1. Dominate trait homozygous

4. Large numbers of offspring are needed for reliable results

5. Start by making a key and writing down what you know.

EXAMPLE: If fire breathing is dominant to not fire breathing in Gregorous Dragon, how can we determine if Mendelia is homozygous dominant or heterozygous?????

SO WHAT DO WE KNOW………….

Let’s say F= fire breathing f= can’t fire breathe.

Set up a two different Punnett squares Both with a homozygous recessive ff

Then as the other parent place a: FF in one Punnett square Ff is another

Essentially, your two Punnett squares will have:Ff crossed with ffFF crossed with ff

INTERPRETATION

If all of the Gregorous dragon babies can firebreathe we can assume that Mendelia is HOMOZYGOUS DOMINANT

If any of the babies DO NOT fire breathe than Mendelia is HETEROZYGOUS

DIFFERENT TYPES OF INHERITANCE

DIHYBRID CROSSES

DIHYBRID CROSSES

Cross that involves two traits

Gives 16 offspringsExample: Pea

color and wrinkles

STEPS FOR A DIHYBRID CROSS

1. Make a key for the two traits that you are crossing

2. Write out the different genotypes of the parents

3. Figure out the possible gametes 1. similar to FOIL2. there are four for each parent3. each gamete must have one allele

from each trait4. Set up and Solve the Punnett Square

EXAMPLE PROBLEM: A MOTHER IS HETEROZYGOUS BROWN HAIR AND BLUE EYES. THE FATHER HAS BLONDE HAIR AND IS HETEROZYGOUS FOR BROWN EYES. WHAT ARE THE POSSIBLE GENOTYPES AND PHENOTYPES OF THEIR OFFSPRINGS?

Step 1 Make a key for the traits

Brown Hair (B) vs Blonde Hair ( b) Brown Eyes (E) vs Blue eyes (e)

Step 2 Genotypes of the parents

Mother Bbee Father bbEe

Step 3 Figure out the possible gamete

Mother Gamete’s Be, Be, be, be Father’s Gamete’s bE, be, bE, be

STEP 4 SET UP AND SOLVE PUNNET SQUARE

Be Be be be

bE

be

bE

be

BbEe

Bbee

BbEe

Bbee

BbEe

Bbee

BbEe

Bbee

bbEe

bbee

bbEe

bbee

bbEe

bbee

bbEe

bbee

COUNT UP THE POSSIBLE GENOTYPES AND PHENOTYPES THAT YOU HAVE FROM YOUR PUNNETT SQUARE

BbEe 4/16

Bbee 4/16

bbEe 4/16

bbee 4/16

Brown Hair; Brown eyes

Brown Hair; Blue eyes

Blonde Hair; Brown eyes

Blonde Hair; Blue eyes

Genotypes Phenotypes

SEX LINKED

SEX LINKED

sex is determined by the X and Y chromosomes.

Females XX

Males XY

SEX DETERMINATION

Sons: get their X chromosome from their mothers

only. Get Their Y chromosome for their fathers

Daughters: fathers must pass their X chromosomes

SEX LINKED TRAITS Traits found on the SEX chromosomes

Genes that are found on the X chromosome follow a have a special pattern of inheritance: X linked traits are only passed to sons from

the mother

Males are much more likely to be affected than females

If trait is recessive, daughters have a second X chromosome so they

can be heterozygous.

Sons only have one X chromosome therefore more likely to express the trait

Females can be carriers and pass the trait onto their son.

Example: Baldness Colorbindness

COLORBLINDNESS

TRY THIS……

A woman is not colorblind but her husband is. Construct a punnett square to determine what is the chance that their children will be colorblind. What is the percentage of children with colorblindness?

A woman who is a carrier for hemophilia marries an unaffected male. What is the % chance that their children will be affected?

INCOMPLETE DOMINANCE

INCOMPLETE DOMINANCE

when one trait is not completely dominant over another

Results heterozygous form being blended together

Example: Pink flower

SOLVING INCOMPLETE DOMINANCE:

Same as performing a regular monohybrid Punnett square

Only difference heterozygous offspring will be mixture of two

trait Ex:

red + white = PINK

Example Problem: Black fur color are not completely dominant to white white fur color. The mother is a homozgygous for black fur color and the father is homozygous for white fur color. Perform a punnett square.

B B

b

b

Bb Bb

Bb Bb

CODOMINANCE

CODOMINANCE Two different alleles are present and both

are expressed

Basically…….. Both alleles contribute to the phenotype.

Example: Red cow X White Cow = Roan Cow Blood types

BLOOD TYPES: Red blood cells are coated with different protein

markers. Person can have either

A B A and B neither protein.

Blood Types are: A B AB O

Genotype Phenotype

IAIA

IAIO

A Blood

IBIB

IBIOB Blood

IAIB AB Blood

IOIO O Blood

EXAMPLE PROBLEM #1

Melissa has type AB blood. Joe has type AB blood as well. If Melissa and Joe have a baby girl, what are the possible blood types the baby can have? HINT: Draw a Punnet Square!!!!!!

EXAMPLE PROBLEM #2

David has blood type AB. Jessica has blood type O. They have a son that has blood type A? Since neither David nor Jessica have this blood type, was their a mistake in the hospital?

HINT: Draw a Punnett Square to help!!!!!!!!!