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Mendel’s Genetics Monohybrid Cross. Gregor Mendel  As discussed last class, he was an Austrian monk  He worked at St. Thomas Monastery  He studied.

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Presentation on theme: "Mendel’s Genetics Monohybrid Cross. Gregor Mendel  As discussed last class, he was an Austrian monk  He worked at St. Thomas Monastery  He studied."— Presentation transcript:

1 Mendel’s Genetics Monohybrid Cross

2 Gregor Mendel  As discussed last class, he was an Austrian monk  He worked at St. Thomas Monastery  He studied both mathematics and botany

3 Why did he actually Succeed?  He chose the appropriate organism to study  He designed and performed his experiments correctly  Analysis of the data was done properly

4 The Patient  The common ______ also known as Pisum sativium  It was chosen for 4 reasons  It was _________ available  Easy to _____and mature  The sex organs are entirely ________ in the flower  Different varieties had different ________

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6 Purebred  What is a purebred organism?  _____________________________ _____________________________  Why was this important to Mendel and his pea plants?  This is because he used purebred plants to conduct all of his experiments

7 How did he make sure?  How did Mendel make sure that his organisms (pea plant) were pure bred?  He bred them as everyone else bred plants, and he looked at _____ ______ at a time  He selected from the ________, only the plants that had the trait that he was looking for  He then bred them together (________) and then he continued this for several generations until no more of the other trait showed up

8 What happened Next?  He repeated this for all the other traits until he had pure bred plants with each trait.

9 The first of the Crosses  So what did he end up doing next?  He started to _______________  He designated the parents as the ____ generations and crossed a true- breeding _____pea plant, with a true- breeding ______ pea plant  The offspring were of course the F1 generation and he also denoted them as __________

10 That F1 Generation  What do you think he saw?  What was the phenotype of the plants?  ____________________________  What is this type of crossing called?

11 Creatively  Creatively the name given to this type of cross is _____________  It is a _______ cross between two purebred plants giving us a hybrid species

12 What did his experiment look like?

13 That’s the Phenotype  We have now seen the phenotype  All of the F1 generations plants were _____  What do you think the genotype must be of the offspring?  First we have to learn some more terms

14 Terms  ___________________ (TT) – Two alleles for a trait that are the same as a result of pure breeding  ___________________ – Having two alleles for a trait that are different  ___________________ - Two alleles for a trait that are the same as a result of pure breeding

15 The First Cross P  F1 Short Tall

16 Lets back track  Yesterday we looked at the different combinations of alleles that an individual can have  We also talked about dominance and recessiveness  What did we say the dominant allele was?  What about the recessive allele

17 What were the parents?  The parent that was tall had a double _______ allele  The parent that was short had a double _______ allele  Both of these parents were homozygous were homozygous

18 When he Crossed  When the parents were crossed, the F1 generation was completely ____________  They all expressed the dominant trait, but why?  _____________________________ _____________________________

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

20 Second Cross Genotype

21 Mendelian Ratio  As Mendel completed the experiment, he found that ____of the offspring of the F1 cross were the ________ (tall) and ____ were the _______ (short)  The Ratio of _____ is known as the _________________

22 Based on observations, Why did this happen?  Each parent in his F1 Generation starts with two hereditary “factors.” One factor is _______ and the other ________  The factors separate out in the and only one of the two factors contribute to the phenotype of the offspring

23 Why did this happen?  The offspring inherit ____ factor from ____ and ____ from ____. If the dominant factor is present, it will be _______, even if the recessive one is present  The recessive factors will be expressed ___ if the recessive factors are present

24 The first Law of heredity  His results gave rise to his first law The law of Segregation

25 The law of segregation  His law of segregation states: __________ _________________________________  These factors segregate in the gametes (after meiosis)  Mendel did not know that his factors were actually genes, we know this today

26 What do we call this?

27 Punnett Square

28 What do they do for us?  Well, they are used by geneticists so that they can _________ the expected ratio (__________) and to suggest possible combinations of _______ in the offspring  They also tell us something about the __________ (the appearance of a trait in an organism)

29 So we saw TT x tt  And for that cross we ended up having a ratio of?  All were Heterozygous (100% - 0%)  What about when we cross the F1 x F1 generations?

30 F1 X F1  What’s the ratio when we are talking about phenotype?  3:1 as well, three of the offspring will present the dominant gene while the fourth will present the recessive gene  What about the genotype ratio?  _____________________________ _____________________________ _____________________________

31 Example

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


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