Mendel’s GeneticsMendel’s Genetics

Monohybrid CrossMonohybrid Cross

Gregor MendelGregor Mendel

As discussed last As discussed last class, he was an class, he was an Austrian monkAustrian monk

He worked at St. He worked at St. Thomas MonasteryThomas Monastery

He studied both He studied both mathematics and mathematics and botanybotany

Why did he actually Why did he actually Succeed?Succeed?

He chose the appropriate organism He chose the appropriate organism to studyto study

He designed and performed his He designed and performed his experiments correctlyexperiments correctly

Analysis of the data was done Analysis of the data was done properlyproperly

The PatientThe Patient The common ______ also The common ______ also

known as known as Pisum sativiumPisum sativium It was chosen for 4 It was chosen for 4

reasonsreasons It was _________ availableIt was _________ available Easy to _____and matureEasy to _____and mature The sex organs are The sex organs are

entirely ________ in the entirely ________ in the flowerflower

Different varieties had Different varieties had different ________different ________

PurebredPurebred

What is a purebred organism?What is a purebred organism? ________________________________________________________________________

____________________________________________ Why was this important to Mendel Why was this important to Mendel

and his pea plants?and his pea plants? This is because he used purebred This is because he used purebred

plants to conduct all of his experimentsplants to conduct all of his experiments

How did he make sure?How did he make sure?

How did Mendel make sure that his How did Mendel make sure that his organisms (pea plant) were pure bred?organisms (pea plant) were pure bred? He bred them as everyone else bred plants, He bred them as everyone else bred plants,

and he looked at _____ ______ at a timeand he looked at _____ ______ at a time He selected from the ________, only the plants He selected from the ________, only the plants

that had the trait that he was looking forthat had the trait that he was looking for He then bred them together (________) and He then bred them together (________) and

then he continued this for several generations then he continued this for several generations until no more of the other trait showed upuntil no more of the other trait showed up

What happened Next?What happened Next?

He repeated this for all the other He repeated this for all the other traits until he had pure bred plants traits until he had pure bred plants with each trait.with each trait.

The first of the CrossesThe first of the Crosses

So what did he end up doing next?So what did he end up doing next? He started to _______________He started to _______________ He designated the parents as the He designated the parents as the

____ generations and crossed a true-____ generations and crossed a true-breeding _____pea plant, with a true-breeding _____pea plant, with a true-breeding ______ pea plantbreeding ______ pea plant

The offspring were of course the F1 The offspring were of course the F1 generation and he also denoted generation and he also denoted them as __________them as __________

That F1 GenerationThat F1 Generation

What do you think he saw?What do you think he saw? What was the phenotype of the What was the phenotype of the

plants?plants? ________________________________________________________

What is this type of crossing called?What is this type of crossing called?

CreativelyCreatively

Creatively the name given to this Creatively the name given to this type of cross is _____________type of cross is _____________

It is a _______ cross between two It is a _______ cross between two purebred plants giving us a hybrid purebred plants giving us a hybrid speciesspecies

What did his experiment What did his experiment look like?look like?

That’s the PhenotypeThat’s the Phenotype

We have now seen the phenotypeWe have now seen the phenotype

All of the F1 generations plants were _____All of the F1 generations plants were _____

What do you think the genotype must be What do you think the genotype must be of the offspring?of the offspring?

First we have to learn some more termsFirst we have to learn some more terms

TermsTerms ___________________ (TT) – Two alleles for a ___________________ (TT) – Two alleles for a

trait that are the same as a result of pure trait that are the same as a result of pure breedingbreeding

___________________ – Having two alleles ___________________ – Having two alleles for a trait that are differentfor a trait that are different

___________________ - Two alleles for a trait ___________________ - Two alleles for a trait that are the same as a result of pure that are the same as a result of pure breedingbreeding

The First Cross PThe First Cross PF1F1

Short

Tall

Lets back trackLets back track

Yesterday we looked at the different Yesterday we looked at the different combinations of alleles that an combinations of alleles that an individual can haveindividual can have

We also talked about dominance We also talked about dominance and recessivenessand recessiveness

What did we say the dominant allele was?What did we say the dominant allele was? What about the recessive alleleWhat about the recessive allele

What were the parents?What were the parents?

The parent that was tall The parent that was tall had a double _______ had a double _______ alleleallele

The parent that was short The parent that was short had a double _______ had a double _______ alleleallele

Both of these parentsBoth of these parents

were homozygouswere homozygous

When he CrossedWhen he Crossed

When the parents were crossed, the When the parents were crossed, the F1 generation was completely F1 generation was completely ________________________

They all expressed the dominant They all expressed the dominant trait, but why?trait, but why?

____________________________________________________________________________________________________________________

So the First cross is So the First cross is done, what about the done, what about the second?second?

Second Cross GenotypeSecond Cross Genotype

Mendelian RatioMendelian Ratio

As Mendel completed the As Mendel completed the experiment, he found that ____of experiment, he found that ____of the offspring of the F1 cross were the offspring of the F1 cross were the ________ (tall) and ____ were the the ________ (tall) and ____ were the _______ (short)_______ (short)

The Ratio of _____ is known as the The Ratio of _____ is known as the __________________________________

Based on observations, Based on observations, Why did this happen?Why did this happen?

Each parent in his F1 Generation Each parent in his F1 Generation starts with two hereditary “factors.” starts with two hereditary “factors.” One factor is _______ and the other One factor is _______ and the other ________________

The factors separate out in the and The factors separate out in the and only one of the two factors only one of the two factors contribute to the phenotype of the contribute to the phenotype of the offspringoffspring

Why did this happen?Why did this happen?

The offspring inherit ____ factor from ____ The offspring inherit ____ factor from ____ and ____ from ____. If the dominant and ____ from ____. If the dominant factor is present, it will be _______, even if factor is present, it will be _______, even if the recessive one is presentthe recessive one is present

The recessive factors will be expressed The recessive factors will be expressed ___ if the recessive factors are present___ if the recessive factors are present

The first Law of heredityThe first Law of heredity

His results gave rise to his first lawHis results gave rise to his first law

The law of SegregationThe law of Segregation

The law of segregationThe law of segregation

His law of segregation states: __________ His law of segregation states: __________ __________________________________________________________________

These factors segregate in the gametes These factors segregate in the gametes (after meiosis)(after meiosis)

Mendel did not know that his factors Mendel did not know that his factors were actually genes, we know this todaywere actually genes, we know this today

What do we call this?What do we call this?

Punnett SquarePunnett Square

What do they do for us?What do they do for us?

Well, they are used by geneticists so that Well, they are used by geneticists so that they can _________ the expected ratio they can _________ the expected ratio (__________) and to suggest possible (__________) and to suggest possible combinations of _______ in the offspringcombinations of _______ in the offspring

They also tell us something about the They also tell us something about the __________ (the appearance of a trait in an __________ (the appearance of a trait in an organism)organism)

So we saw TT x ttSo we saw TT x tt

And for that cross we ended up And for that cross we ended up having a ratio of?having a ratio of? All were Heterozygous (100% - 0%)All were Heterozygous (100% - 0%)

What about when we cross the F1 x What about when we cross the F1 x F1 generations?F1 generations?

F1 X F1F1 X F1

What’s the ratio when we are What’s the ratio when we are talking about phenotype?talking about phenotype? 3:1 as well, three of the offspring will 3:1 as well, three of the offspring will

present the dominant gene while the present the dominant gene while the fourth will present the recessive genefourth will present the recessive gene

What about the genotype ratio?What about the genotype ratio? ________________________________________________________________________

______________________________________________________________________________________________________

ExampleExample

Class WorkClass Work

Read Pages 202 -212Read Pages 202 -212 Complete Questions 205 #1, 5, 6Complete Questions 205 #1, 5, 6 Page 207 #1, 3, 6, 9, 10, 11, 12Page 207 #1, 3, 6, 9, 10, 11, 12