A. Where did I get these A. Where did I get these freckles?freckles?

B. Why is my brother so B. Why is my brother so athletic and I’m so athletic and I’m so clumsy?clumsy?

C. Why do diseases show up C. Why do diseases show up in some generations and in some generations and not others?not others?

The answer…The answer…

Heredity!!!Heredity!!!

Mating Game ActivityMating Game Activity

HEREDITYHEREDITY

A.A.HeredityHeredity—the passing of —the passing of traits from parents to traits from parents to offspringoffspring

B.B.TraitsTraits—the physical or —the physical or behavioral characteristics behavioral characteristics passed to offspringpassed to offspring

MENDEL & HEREDITYMENDEL & HEREDITY

For thousands of For thousands of years people have years people have noticed that offspring noticed that offspring resembled their resembled their children…Could this children…Could this man have the man have the answer?answer?

MENDEL & HEREDITYMENDEL & HEREDITY

A.A.Gregor Mendel, an Gregor Mendel, an Austrian monk, studied Austrian monk, studied garden peas for 14 years.garden peas for 14 years.

B.B.He would cross “pure” He would cross “pure” plants of opposite traits plants of opposite traits and observe their and observe their offspring.offspring.

MENDEL & HEREDITYMENDEL & HEREDITYC. C. GametesGametes—male and —male and female sex cells (sperm and female sex cells (sperm and egg)egg)

1. Mendel chose pea plants 1. Mendel chose pea plants because each plant has because each plant has male and female gametes. male and female gametes.

MENDEL & HEREDITYMENDEL & HEREDITY

D. D. PollinationPollination—the transfer of —the transfer of pollen grains (containing pollen grains (containing sperm) to the female sperm) to the female reproductive organs in the reproductive organs in the same flowersame flower1. Mendel used cross-1. Mendel used cross-pollination (2 flowers)pollination (2 flowers)

MENDEL & HEREDITYMENDEL & HEREDITY

E. E. FertilizationFertilization—the joining of —the joining of male and female gametes.male and female gametes.

F. F. ZygoteZygote—a fertilized cell—a fertilized cell1. Every living thing begins 1. Every living thing begins as a zygote!as a zygote!

MENDEL & HEREDITYMENDEL & HEREDITYG. G. HybridHybrid—the offspring of —the offspring of parents that have different parents that have different traitstraits

1. Tall x Short1. Tall x Short

H. H. Monohybrid CrossMonohybrid Cross—only —only ONE trait is differentONE trait is different

MENDEL & HEREDITYMENDEL & HEREDITY

I. Mendel was a careful I. Mendel was a careful researcherresearcher

1. Studied one trait at a time1. Studied one trait at a time

2. Used “pure” plant lines2. Used “pure” plant lines

3. Used a large # of plants 3. Used a large # of plants and many trialsand many trials

MENDEL’S RULESMENDEL’S RULESa)a)Genes are sections of Genes are sections of

DNA located on theDNA located on the chromosomechromosome

b) Genes are like ice cream, b) Genes are like ice cream, alleles are the different alleles are the different flavorsflavors AAaa

MENDEL’S RULESMENDEL’S RULESB. B. The Rule of DominanceThe Rule of Dominance

1. When one trait covers up 1. When one trait covers up another trait it is said to be another trait it is said to be ““dominantdominant””

a) Write in capital lettersa) Write in capital lettersb) AAb) AA

MENDEL’S RULESMENDEL’S RULES2. The trait that is covered up is 2. The trait that is covered up is

““recessiverecessive””a) Trait only shows up when 2 a) Trait only shows up when 2 recessive alleles are inherited recessive alleles are inherited from parentsfrom parentsb) Write in lower case lettersb) Write in lower case lettersb) aab) aa

MENDEL’S RULESMENDEL’S RULES3. When one dominant allele 3. When one dominant allele

(A) and one recessive allele (A) and one recessive allele (a) is inherited, the dominant (a) is inherited, the dominant allele shows upallele shows up

a) AA=Tall a) AA=Tall b) aa=Shortb) aa=Shortc)Aa=Tallc)Aa=Tall

MENDEL’S LAWSMENDEL’S LAWSC. C. The Law of SegregationThe Law of Segregation

1. Since each gene has two 1. Since each gene has two alleles, it can produce two alleles, it can produce two different gametesdifferent gametes2. The alleles separate2. The alleles separate3. Male and female gametes 3. Male and female gametes pair up randomly creating 4 pair up randomly creating 4 possible combinationspossible combinations

GENOTYPEGENOTYPEA. A. GenotypeGenotype—the combination —the combination

of alleles in the organismof alleles in the organism

1. AA or Aa or aa1. AA or Aa or aa

2. The letters!2. The letters!

GENOTYPEGENOTYPE

B. B. HomozygousHomozygous—both alleles —both alleles are dominant or recessiveare dominant or recessive

1. AA or aa1. AA or aa

C. C. HeterozygousHeterozygous—one allele is —one allele is recessive and one is dominantrecessive and one is dominant

2. Aa 2. Aa

PHENOTYPEPHENOTYPEA. A. PhenotypePhenotype—the outward —the outward appearance or behavior of appearance or behavior of the organismthe organism

1. Tall or Short1. Tall or Short

2. What it looks like!2. What it looks like!

MENDEL’S EXPERIMENTMENDEL’S EXPERIMENT

A. Tall x ShortA. Tall x Short

1. All tall plants were > 6 ft1. All tall plants were > 6 ft

2. All short plants were < 2ft2. All short plants were < 2ft

3. The original generation is 3. The original generation is called “P1”called “P1”

4. See page 2554. See page 255

MENDEL’S EXPERIMENTMENDEL’S EXPERIMENT

B. Results: The offspring B. Results: The offspring were ALL Tall!!!were ALL Tall!!!

1. This generation were 1. This generation were called “F1”called “F1”

MENDEL’S EXPERIMENTMENDEL’S EXPERIMENT

C. Next, he crossed the F1sC. Next, he crossed the F1sD. Results: ¾ were Tall and D. Results: ¾ were Tall and

¼ were short (3:1 ratio)¼ were short (3:1 ratio)1. The short plants 1. The short plants

reappeared from nowhere!reappeared from nowhere!2. This generation was called 2. This generation was called

“F2”“F2”

MENDEL’S RULESMENDEL’S RULESA. A. The Rule of Unit FactorsThe Rule of Unit Factors

1. Each organism inherits 1. Each organism inherits one possibility for a trait one possibility for a trait from each parentfrom each parent

2. 2. AllelesAlleles—Different form —Different form of a traitof a trait

PUNNETT SQUARESPUNNETT SQUARES

A. Punnett Squares are used A. Punnett Squares are used to predict the probability of a to predict the probability of a genotype to occurgenotype to occur

PUNNETT SQUARESPUNNETT SQUARES

B. Probability can be written B. Probability can be written as a fraction, ratio or as a fraction, ratio or percentpercent

1. ¾ , ¼ 1. ¾ , ¼

2. 3:12. 3:1

3. 75%, 25%3. 75%, 25%

PUNNETT SQUARESPUNNETT SQUARESC. Can also be C. Can also be

used for used for dihybrid dihybrid crosses (2 crosses (2 traits)traits)

__________________________________________________

RR & Rr=roundRR & Rr=roundrr= wrinkledrr= wrinkledYY & Yy= yellowYY & Yy= yellowyy= greenyy= green

RY Ry rY ryRY Ry rY ry

RYRY

RyRy

rYrY

ryry

RRYYRRYY

MENDEL’S LAST LAWMENDEL’S LAST LAWA. A. The Law of Independent The Law of Independent AssortmentAssortment

1. Genes for different 1. Genes for different traits, for example shape traits, for example shape and color, are inherited and color, are inherited independent from each independent from each other.other.

MENDEL’S LAST LAWMENDEL’S LAST LAW2. The two different 2. The two different

genes have nothing to do genes have nothing to do with each other.with each other.

3. 3. Exception: Unless the Exception: Unless the genes for the two traits are genes for the two traits are on the same chromosome!!!on the same chromosome!!!

REVIEWREVIEW

What is a hybrid?What is a hybrid?

THE OFFSPRING OF THE OFFSPRING OF PARENTS THAT HAVE PARENTS THAT HAVE

DIFFERENT DIFFERENT TRAITS/ALLELESTRAITS/ALLELES

REVIEWREVIEW

What is the name for the What is the name for the parent generation? The parent generation? The

offspring? offspring?

P1P1

F1F1

REVIEWREVIEW

What happens to a What happens to a recessive trait when a recessive trait when a

dominant allele is dominant allele is present?present?

IT DOES NOT SHOW UP!IT DOES NOT SHOW UP!

REVIEWREVIEW

Give an example of a Give an example of a heterozygous organism heterozygous organism

using the letter Q.using the letter Q.

QqQq

REVIEWREVIEW

What’s the difference What’s the difference between genotype and between genotype and

phenotype?phenotype?

G=combination of allelesG=combination of alleles

P=the outward appearanceP=the outward appearance

REVIEWREVIEW

If the results of your If the results of your punnett square were 1 punnett square were 1

AA, 2 Aa and 1 aa, what AA, 2 Aa and 1 aa, what is probability ratio?is probability ratio?

1:2:11:2:1