Do NowDo Now

What is an inheritance? What is an inheritance? Something passed from one generation to the Something passed from one generation to the

next.next.

How is it determined?How is it determined? Your genes from your parents!Your genes from your parents!

What are some things you What are some things you

inherited?inherited?

GeneticsGenetics

It all started with Mendel!It all started with Mendel!

Review: Types of ReproductionReview: Types of Reproduction

Sexual reproduction: Sexual reproduction: twotwo organisms organisms produce a new produce a new uniqueunique organism = organism = VARIABLITYVARIABLITY!!!!!!

Asexual reproduction: Asexual reproduction: oneone organism organism produces a new nearly produces a new nearly identicalidentical organism organism = = no variabilityno variability!!

Sexual ReproductionSexual Reproduction

Since the hereditary material comes from Since the hereditary material comes from two parents it two parents it resemblesresembles both parents in both parents in some ways, but is also some ways, but is also differentdifferent from both from both in others.in others.

It has all the characteristics of its species, It has all the characteristics of its species, but at the same time has its own but at the same time has its own individualindividual characteristics that distinguish it from all characteristics that distinguish it from all other members of that species.other members of that species.

• The branch of biology that is concerned The branch of biology that is concerned with the ways in which with the ways in which hereditaryhereditary information is transmitted information is transmitted from parents from parents to offspring.to offspring.

GeneticsGenetics

Gregor MendelGregor Mendel

An Austrian monk that studied math and An Austrian monk that studied math and science and taught science in a monastery science and taught science in a monastery

Performed experiments as he maintained Performed experiments as he maintained the monastery gardenthe monastery garden

Performed the first scientific study of Performed the first scientific study of inheritanceinheritance on on pea plantspea plants

Pea PlantsPea PlantsUse parts of the flowers to reproduceUse parts of the flowers to reproduce Pollen = male sex cellsPollen = male sex cells Eggs in flower = female sex cellsEggs in flower = female sex cells

Pea plants normally reproduce by Pea plants normally reproduce by self-pollinationself-pollination Pollen fertilizes flower of the same plantPollen fertilizes flower of the same plant True-breedingTrue-breeding pea plants (“pure bred”) pea plants (“pure bred”)

Would the new plants be identical or different than the Would the new plants be identical or different than the parent? Why?parent? Why?

} form a seed

Pea PlantsPea PlantsPea plants can Pea plants can cross-pollinatecross-pollinate Pollen fertilizes flower of a Pollen fertilizes flower of a differentdifferent plant plant New plants have New plants have twotwo parent plants parent plants

Infer if the new plants would be identical or Infer if the new plants would be identical or different from the parents. Why?different from the parents. Why?

Mendel cross-pollinated pea plants!Mendel cross-pollinated pea plants!

Mendel’s 1Mendel’s 1stst experiments experiments

TraitTrait = specific characteristic that varies from = specific characteristic that varies from one individual to anotherone individual to another Height (tall or short)Height (tall or short) Seed color (green or yellow)Seed color (green or yellow) Seed texture (smooth or wrinkled) Seed texture (smooth or wrinkled)

Mendel crossed plants with contrasting traitsMendel crossed plants with contrasting traits PP (Parental) = original pair of plants (Parental) = original pair of plants FF11 (First Filial) = first set of offspring (First Filial) = first set of offspring

(filius means “(filius means “sonson” in Latin)” in Latin) HybridsHybrids = offspring of parents crossed with = offspring of parents crossed with

different traitsdifferent traits

Try to predict the results…Try to predict the results…

Mendel’s 1Mendel’s 1stst results results

All of the FAll of the F11 hybrid offspring had the hybrid offspring had the

characteristic of only characteristic of only oneone of the parents of the parents

(so it appeared that the characteristic of the (so it appeared that the characteristic of the other parent had disappeared)other parent had disappeared)

Mendel’s 1Mendel’s 1stst conclusions conclusions

Biological inheritance is determined by Biological inheritance is determined by factors passed from one generation to the factors passed from one generation to the next = next = genesgenes

Each gene occurred in two contrasting Each gene occurred in two contrasting forms that produced different forms that produced different characteristics = characteristics = allelesalleles

The Principle of DominanceThe Principle of Dominance

Some alleles are Some alleles are dominantdominant

and and

others are others are recessiverecessive

Think about it like this…Think about it like this…

What happened?What happened?

If there are at least two alleles for each If there are at least two alleles for each trait, what happened to the other allele that trait, what happened to the other allele that was inherited? was inherited?

Did the recessive alleles disappear or Did the recessive alleles disappear or were they hiding? were they hiding?

Dominant vs. RecessiveDominant vs. Recessive

An organism with a dominant allele for a An organism with a dominant allele for a particular trait will always have that formparticular trait will always have that form When will a dominant allele show up?When will a dominant allele show up? The characteristic almost The characteristic almost alwaysalways shows up shows up

An organism with a recessive allele for a An organism with a recessive allele for a particular trait will have that form only when particular trait will have that form only when the dominant allele for the trait is not presentthe dominant allele for the trait is not present When will a recessive allele show up?When will a recessive allele show up? The characteristic only shows up when the The characteristic only shows up when the

dominant allele is not presentdominant allele is not present

Mendel’s 2Mendel’s 2ndnd experiments experiments

Mendel crossed the FMendel crossed the F11 hybrid plants hybrid plants FF11 (First Filial) = first set of offspring (hybrids)(First Filial) = first set of offspring (hybrids)

FF22 (Second Filial) = offspring of self-pollinated F(Second Filial) = offspring of self-pollinated F11

Dominant vs. Recessive allelesDominant vs. Recessive alleles Upper case letter Upper case letter = dominant allele= dominant allele Lower case letter Lower case letter = recessive allele= recessive allele

P Generation F1 Generation F2 Generation

Tall Short Tall TallTall Tall Tall Short

Section 11-1

Principles of Dominance

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Try to predict the results…Try to predict the results…

Mendel’s 2Mendel’s 2ndnd results results

The traits controlled by the recessive alleles The traits controlled by the recessive alleles reappearedreappeared! = 25% of F! = 25% of F22 plants plants There is a new combination of alleles!There is a new combination of alleles!

How did the trait disappear and then reappear?How did the trait disappear and then reappear?

Mendel’s 2Mendel’s 2ndnd conclusions conclusions

The dominant allele masked the corresponding The dominant allele masked the corresponding recessive allele in the Frecessive allele in the F11 generation generation

The reappearance in the FThe reappearance in the F22 generation indicated generation indicated

that the alleles that the alleles separatedseparated during gamete (sex during gamete (sex cell) formationcell) formation Each gamete contains a single copy of each Each gamete contains a single copy of each

genegene The recessive alleles can be The recessive alleles can be pairedpaired up again up again

in the Fin the F22 generation generation

The Principle of SegregationThe Principle of Segregation

Alleles are Alleles are separatedseparated (segregated) (segregated)

during during

gametegamete (sex cell) formation. (sex cell) formation.

Think about it like this…Think about it like this…

concluded that

which is called the

which is called the

GregorMendel

Law ofDominance

Law ofSegregation

Peaplants

“Factors”determinetraits

Some alleles are dominant, and some alleles are recessive

Alleles are separated during gamete formation

Section 11-3

Concept Map

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experimented with