Genetics and Genetics and InheritanceInheritance

Chapter 10: Section 1Chapter 10: Section 1

Puppy-Dog Creations…Puppy-Dog Creations…

ChooseChoose

BLUE or YELLOW paperBLUE or YELLOW paper

FEMALE or MALEFEMALE or MALE

SQUARE eyes or ROUND eyesSQUARE eyes or ROUND eyes

OVAL nose or TRIANGULAR noseOVAL nose or TRIANGULAR nose

POINTED teeth or SQUARE teethPOINTED teeth or SQUARE teeth

***The rest is up to you!******The rest is up to you!***

Note to Students:Note to Students:

In this section vocabulary is In this section vocabulary is extremely important. It leads the extremely important. It leads the way to the rest of your way to the rest of your understanding.understanding.

As always, ask questions if you do As always, ask questions if you do not understand!not understand!

VOCABULARYVOCABULARY

TRAITS- a genetic (inherited) TRAITS- a genetic (inherited) characteristiccharacteristic

HEREDITY- The passing of traits from HEREDITY- The passing of traits from parent to offspringparent to offspring

GENETICS- the branch of biology that GENETICS- the branch of biology that studies heredity (inherited traits)studies heredity (inherited traits)

Gregor MendelGregor Mendel

Who? Monk (priest) Who? Monk (priest)

What? Curious gardener trained in What? Curious gardener trained in math and sciencemath and science

When? 1851 is when it all began…When? 1851 is when it all began…

Where? Austria (central Europe)Where? Austria (central Europe)

Curiosity Leads the WayCuriosity Leads the Way

He was curious as to why plants, specifically garden He was curious as to why plants, specifically garden pea plants, had different physical characteristics pea plants, had different physical characteristics (short/tall, yellow seeds/green seeds, purple/white flowers, etc.)(short/tall, yellow seeds/green seeds, purple/white flowers, etc.)

Observed that TRAITS were often similar to those of Observed that TRAITS were often similar to those of their parentstheir parents

Spent over 10 years experimenting with the Spent over 10 years experimenting with the thousands of pea plants to understand HEREDITYthousands of pea plants to understand HEREDITY

He was the first person to succeed in predicting He was the first person to succeed in predicting how traits are transferred from one generation to how traits are transferred from one generation to the next.the next.

His work formed the foundation of GENETICSHis work formed the foundation of GENETICS

Why Pea Plants?Why Pea Plants? Easy to growEasy to grow

Grow quicklyGrow quickly

Produce large number of offspring in one Produce large number of offspring in one generation generation (lots of data available at one time) (lots of data available at one time)

They have many traits that exist in only They have many traits that exist in only two forms two forms (makes it easier to study them)(makes it easier to study them)

Pea plants have both male and female Pea plants have both male and female parts on the same flower; so fertilization parts on the same flower; so fertilization can be controlled.can be controlled.

Plant VocabularyPlant Vocabulary GametesGametes- male and female sex cells- male and female sex cells

FertilizationFertilization- male gamete unites with - male gamete unites with the female gametethe female gamete

ZygoteZygote- the fertilized cell that develops - the fertilized cell that develops into a seed.into a seed.

PollinationPollination- transfer of pollen grains from - transfer of pollen grains from male reproductive organ to female male reproductive organ to female reproductive organ.reproductive organ.

Pistil-female sex cellsPistil-female sex cells Stamen-male sex cells Stamen-male sex cells

(pollen)(pollen) NOTE- in nature these NOTE- in nature these

plants would be self-plants would be self-pollinatingpollinating

Mendel developed a Mendel developed a way to cross-pollinate way to cross-pollinate pea plantspea plants– Remove pollen from Remove pollen from

a flower on one a flower on one plant and brush it plant and brush it on a flower of a on a flower of a second plantsecond plant

– To prevent self-To prevent self-pollination he pollination he carefully removed carefully removed the stamens from the stamens from the flowers on the the flowers on the second plantssecond plants

FIGURE 10.1 FIGURE 10.1

Vocabulary ContinuedVocabulary Continued Self-pollinatingSelf-pollinating- The pollen of one flower - The pollen of one flower

lands on the pistil of the same flowerlands on the pistil of the same flower

Cross-PollinatingCross-Pollinating- The pollen of one flower - The pollen of one flower is placed on the pistil of a different flower.is placed on the pistil of a different flower.**To prevent self-pollination Mendel removed the **To prevent self-pollination Mendel removed the

stamen from the flowers on the second flower.**stamen from the flowers on the second flower.**

Pure bredPure bred- always produces offspring with - always produces offspring with the same form of a trait as the parent….its the same form of a trait as the parent….its pure!pure!

Let the Experiment Let the Experiment Begin!Begin!

Mendel crossed PUREBRED plants Mendel crossed PUREBRED plants with opposite forms of the same trait. with opposite forms of the same trait. For example he crossed a purebred For example he crossed a purebred tall plant with a purebred short plant.tall plant with a purebred short plant.

– Why purebreds??? Because those were Why purebreds??? Because those were the plants that he knew what to expect the plants that he knew what to expect from the offspring. from the offspring.

Mendel carefully controlled his Mendel carefully controlled his experiments making sure that he experiments making sure that he studied only one trait at a time to studied only one trait at a time to

control the variables.control the variables.

Experiment #1Experiment #1

Characteristic:Characteristic: Tall Plant vs Short Tall Plant vs Short PlantPlant

NOTENOTE: The parent plants were called the : The parent plants were called the parent parent generation or P generationgeneration or P generation and the offspring from and the offspring from

this cross were called the this cross were called the F1 generationF1 generation..

Results:Results: ALL F1 generation plants were ALL F1 generation plants were tall! The short trait had “disappeared”.tall! The short trait had “disappeared”.

Experiment #2Experiment #2

He then allowed all of the F1 He then allowed all of the F1 generation to self-pollinate.generation to self-pollinate.

This generation was called the F2 This generation was called the F2 generation.generation.

Results:Results: He discovered that about ¾ He discovered that about ¾ of them were tall and ¼ were short. of them were tall and ¼ were short. Short trait had returned!Short trait had returned!

Experiment #3-???Experiment #3-???

He tested all of the He tested all of the other main traitsother main traits– Flower color, Seed Flower color, Seed

shape, seed color, shape, seed color, seed coat color, pod seed coat color, pod shape, pod color, shape, pod color, and flower position.and flower position.

Results:Results: All of the All of the traits had the same traits had the same results as plant results as plant height!height!

HybridsHybrids- offspring of parents that - offspring of parents that have different forms of a trait.have different forms of a trait.

MonohybridMonohybrid- Mendel’s first - Mendel’s first experiments were monohybrids experiments were monohybrids because they differed only by a single because they differed only by a single trait. trait.

ConclusionsConclusions

Individual Individual factorsfactors must control the must control the inheritance of traits in peas.inheritance of traits in peas.– Factors exist in pairsFactors exist in pairs– Female contributes one trait and the Female contributes one trait and the

male contributes the othermale contributes the other– One factor can mask/hide the other One factor can mask/hide the other

factorfactor

Vocabulary…cont.Vocabulary…cont.

““Factors” that control traits are called Factors” that control traits are called GENESGENES, they are , they are located on chromosomes.located on chromosomes.

Different forms of a gene are called Different forms of a gene are called ALLELESALLELESex: two alleles for height: short and tall, purple vs. whiteex: two alleles for height: short and tall, purple vs. white

An organism's two alleles are located on different copies of An organism's two alleles are located on different copies of a chromosome one from mom and one from dad.a chromosome one from mom and one from dad.

Individual alleles control the inheritance of traits. Some Individual alleles control the inheritance of traits. Some alleles are alleles are dominantdominant while others are while others are recessiverecessive..

**Dominant allelesDominant alleles will always show up if they are will always show up if they are present.present.

**Recessive allelesRecessive alleles are covered up when are covered up when dominants dominants

are present.are present.

Mendel concluded that every plant in Mendel concluded that every plant in the F1 generation had one allele for the F1 generation had one allele for Tall height and one allele for short Tall height and one allele for short height. height.

Take out your puppy-dogs!Take out your puppy-dogs!

– Answer Questions 1-2Answer Questions 1-2

– Dominant alleles are: B (blue skin), Dominant alleles are: B (blue skin), R (round eyes), T (triangular nose), R (round eyes), T (triangular nose), and P (pointed teeth)and P (pointed teeth)

The Law of SegregationThe Law of Segregation Recall the results of Mendel’s cross between F1 Recall the results of Mendel’s cross between F1

plantsplants

Rules:Rules: Each tall plant in the F1 generation carried Each tall plant in the F1 generation carried one dominant allele for tallness and one one dominant allele for tallness and one unexpressed recessive allele for shortness. unexpressed recessive allele for shortness. (F1 plants (F1 plants received 1 allele from each P-generation parent)received 1 allele from each P-generation parent)

The LawThe Law: Every individual has two alleles of : Every individual has two alleles of each gene. When gametes are produced, each gene. When gametes are produced, each gamete receives one of these alleles at each gamete receives one of these alleles at random. There are a total of four random. There are a total of four combinations of alleles.combinations of alleles.

Another Rule from Mendel:Another Rule from Mendel:

Rule of Dominance-Rule of Dominance- Only one of the Only one of the two alleles (dominant allele) for each two alleles (dominant allele) for each trait actually determines the trait that trait actually determines the trait that will show up. The alternate form of the will show up. The alternate form of the trait (recessive allele) is only present if trait (recessive allele) is only present if the dominant trait is not.the dominant trait is not.

History Rap-upHistory Rap-up

Mendel tried to present his results to other Mendel tried to present his results to other scientists; however, some felt that he had scientists; however, some felt that he had over-simplified inheritance while others over-simplified inheritance while others would not even read his findings.would not even read his findings.

It took 34 years before people began to It took 34 years before people began to realize how important his work really was.realize how important his work really was.

Today Mendel is often referred to as the Today Mendel is often referred to as the FATHER OF GENETICSFATHER OF GENETICS

Question of the Day…Question of the Day…

Why do you think people Why do you think people often look very similar to often look very similar to

other family members, but other family members, but also different?also different?

How genetically similar are How genetically similar are you to your classmates???you to your classmates???

Class Traits activityClass Traits activity CompareCompare NotesNotes Finish ActivityFinish Activity

Vocabulary Once more…Vocabulary Once more… Phenotype-Phenotype- its physical its physical

appearance (visible traits)appearance (visible traits)

Genotype-Genotype- genetic makeup genetic makeup or allele combinations.or allele combinations.

Homozygous (pure bred)-Homozygous (pure bred)- organism with two identical organism with two identical alleles for a trait (purebred)alleles for a trait (purebred)– Homozygous dominant Homozygous dominant

(TT)(TT)– Homozygous recessive (tt)Homozygous recessive (tt)

Heterozygous (hybrid)-Heterozygous (hybrid)- two different alleles for the two different alleles for the same trait (hybrid)same trait (hybrid)

PhenotypePhenotype GenotypeGenotype

TallTall TTTT

TallTall TtTt

ShortShort tttt

Notice: two genotypes for tall-can’t tell the difference by looking at them.

Finish Class Survey ActivityFinish Class Survey Activity

Bell Work: 11-8Bell Work: 11-8

Take out your simple genetics Take out your simple genetics practice problems that you practice problems that you picked up on Friday.picked up on Friday.

Complete the front page, using Complete the front page, using your notes to help you.your notes to help you.

What is probability?What is probability?

The likelihood that a particular event will The likelihood that a particular event will occur.occur.

For example we would say that any coin that is tossed will have For example we would say that any coin that is tossed will have a 1 in 2 chances of landing heads up…BUT if you were to toss a a 1 in 2 chances of landing heads up…BUT if you were to toss a coin 20 times you might expect it to be 10 heads and 10 tails coin 20 times you might expect it to be 10 heads and 10 tails but that might not be the case.but that might not be the case.

Laws of probability PREDICT what is likely to Laws of probability PREDICT what is likely to occur not necessarily what WILL occur. occur not necessarily what WILL occur. However, the more tosses you make, the However, the more tosses you make, the more accurate you’ll be.more accurate you’ll be.

Probability in GeneticsProbability in Genetics Mendel, mathematician and scientist, was Mendel, mathematician and scientist, was

the first to recognize that the principles of the first to recognize that the principles of probability can be used to predict the probability can be used to predict the results of genetic crosses.results of genetic crosses.

Mendel carefully counted the offspring from Mendel carefully counted the offspring from every cross. Every time he crossed two every cross. Every time he crossed two hybrid plants (Tt) ¾ of the F1 generation hybrid plants (Tt) ¾ of the F1 generation would be tall and ¼ would be short.would be tall and ¼ would be short.

Mendel could say that the probability of Mendel could say that the probability of such a cross producing a tall plant was 3 in such a cross producing a tall plant was 3 in 4 chances.4 chances.

PUNNET SQUARESPUNNET SQUARES Used to relate probability to genetics.Used to relate probability to genetics.

Shows all of the possible outcomes of a Shows all of the possible outcomes of a genetic cross genetic cross

Allows you to determine the probability of a Allows you to determine the probability of a particular outcome (possible genotypes in particular outcome (possible genotypes in the offspring)the offspring)

You can predict probabilities of the offspring You can predict probabilities of the offspring IF you know the genotypes of the parents.IF you know the genotypes of the parents.

Monohybrid CrossesMonohybrid Crosses

You need a 2x2 boxYou need a 2x2 box

Each parent can Each parent can produce two kinds of produce two kinds of gametes or alleles for gametes or alleles for this trait.this trait.

Once the boxes are Once the boxes are filled in you have all of filled in you have all of the possible the possible genotypes for a genotypes for a particular traitparticular trait

From that information From that information you can determine the you can determine the phenotypes.phenotypes.

Understanding the Understanding the CrossesCrosses

Always use the same letter for different alleles of the same gene.

Capital Letters stand for dominant alleles.

Lower case letters stand for recessive alleles

Dominant allele is always written first.

It does NOT matter where each parent is placed. One on top, one on the left side.

Meaning Behind the Meaning Behind the SymbolsSymbols

TtTt TtTt

TtTt TtTt

T T

t

t

P-generation: Tall P-generation: Tall Purebred (TT) and Purebred (TT) and Short Purebred (tt)Short Purebred (tt)

All four possibilities posses a tall gene so in every case the recessive, short gene, will be hidden.

All F1 plants are considered to be hybrids- they have two different alleles for the same trait, rather than being purebreds.

Punnet Squares Practice SheetPunnet Squares Practice Sheet

Mendel’s Dihybrid CrossesMendel’s Dihybrid Crosses

He used Peas that differed from each He used Peas that differed from each other by 2 traits instead of just one.other by 2 traits instead of just one.

The question he was asking: The question he was asking: Will the Will the two traits stay together in the two traits stay together in the next generation or will they be next generation or will they be inherited independently of each inherited independently of each other?other?

Dihybrid Cross ExperimentDihybrid Cross Experiment

CharacteristicsCharacteristics: True-bred round, yellow : True-bred round, yellow seeds and a true-bred wrinkled, green seeds and a true-bred wrinkled, green seedsseeds

He already knewHe already knew: Round and Yellow : Round and Yellow were dominant from his monohybrid were dominant from his monohybrid crosses.crosses.

Results:Results: All Seeds were round and yellow. All Seeds were round and yellow.

Dihybrid Cross Experiment Dihybrid Cross Experiment #2#2

Allow the F1 generation to self pollinate.Allow the F1 generation to self pollinate.

Results were that F2 varied greatly: Results were that F2 varied greatly: round/yellow seeds, wrinkled/green seeds, round/yellow seeds, wrinkled/green seeds, round/green seeds, and wrinkled/yellow seeds.round/green seeds, and wrinkled/yellow seeds.

In the F2 generation he again counted a In the F2 generation he again counted a definite ratio of physical characteristics: 9 definite ratio of physical characteristics: 9 round/yellow, 3 round/green, 3 round/yellow, 3 round/green, 3 wrinkled/yellow, and 1 wrinkled/green (9:3:3:1)wrinkled/yellow, and 1 wrinkled/green (9:3:3:1)

Conclusions to DihybridConclusions to Dihybrid Cross Experiments Cross Experiments

Mendel was able to express his second Law Mendel was able to express his second Law from the results and he called it: from the results and he called it: The Law The Law of Independent Assortmentof Independent Assortment– Genes of different traits are inherited Genes of different traits are inherited

independentlyindependently

Why was he able to make this Why was he able to make this conclusion?conclusion? Because if the alleles for seed Because if the alleles for seed shape and color were inherited together shape and color were inherited together only 2 kinds of pea seeds would have been only 2 kinds of pea seeds would have been produced instead of variations of all produced instead of variations of all combinations.combinations.

Dihybrid Punnet SquaresDihybrid Punnet Squares

4x4 box because each combination 4x4 box because each combination must be considered.must be considered.

2 traits per box2 traits per box

See Figure 10.8 in your book (pg See Figure 10.8 in your book (pg 261).261).

Dihybrid Cross Punnet Dihybrid Cross Punnet SquareSquare

Example: What happens if a man who is heterozygous brown eyes AND heterozygous tongue roller has children with a woman who is homozygous blue eyes AND heterozygous tongue roller?? What is the chance that their child will be a blue eyed non-tongue roller?

Due to Mendel’s Law of Independent Assortment, we must look at all possible allele combinations that can go into sperm and egg. We will use a method of distribution you may have seen in math class called FOIL. FOIL stands for First, Outside, Inside, Last.

Practice: Foil the following genotype: BbWw

(F) _____, (O) ______, (I) _____, (L) ____

Now we’re ready to tackle the example problem above.

What happens if a man who is heterozygous brown eyes AND heterozygous tongue roller has children with a woman who is homozygous blue eyes AND heterozygous tongue roller??

Dad’s Genotypes: ____________ _____________

Possible Sperm Alleles: ______ or _______ or ______ or _______

Mom’s Genotypes: _____________ _____________

Possible Egg Alleles: ______ or _______ or _______ or _________

What is the chance their child will be a blue-eyed non-tongue roller?

______ out of _____ or ______%

Dad: Homozygous blue eyes AND Heterozygous Widow’s Peak ____________

Mom: Heterozygous brown eyes AND Heterozygous Widow’s Peak ___________

Genes Discovery WorksheetGenes Discovery Worksheet Dihybrid Cross WorksheetDihybrid Cross Worksheet Puppy Dog madness ActivityPuppy Dog madness Activity Oompa Loompa Activity.Oompa Loompa Activity. QuizQuiz