Ch 5.2 understanding inheritance

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Transcript of Ch 5.2 understanding inheritance

Slide 1

Lesson 2 Reading GuideWhat determines the expression of traits?How can inheritance be modeled?How do some patterns of inheritance differ from Mendels model?

Focus Questions

2Mendel concluded that two factorsone from each parentcontrol each trait (called chromosomes).Chromosomes are made of coiled up DNAGenes are segments of DNA for 1 trait.Lesson 21. What determines the expression of traits?

3Lesson 2Remember that DNA stores genetic info.Alleles different forms of a geneEach chromosome has 1 allele for every gene on it.Ex: Color of pea plant is found in 1 gene, alleles are purple and whiteThe two chromosomes in an offspring cell may have the same or different alleles.

1. What determines the expression of traits? 4Lesson 2

211_links widow gene5

Lesson 2Phenotype how a trait physically appearsGenotype the 2 alleles (genes) that control the phenotype of a trait

1. What determines the expression of traits? 6Lesson 2What Controls Traits (cont.)phenotypefrom Greek phainein, means to show

7A pea plant that is YyGenotypePhenotype45

8A pea plant that is greenGenotypePhenotype

459The two allelesGenotypePhenotype

4510A fruit fly has curly wingsGenotypePhenotype

4511How the trait appearsGenotypePhenotype

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Lesson 2Homozygous = same alleles (ex: RR, rr)Heterozygous = different alleles (ex: Rr)

1. What determines the expression of traits? 13What is the genotype? RrHomozygous dominantHomozygous recessiveHeterozygous45

14What is the genotype? wwHomozygous dominantHomozygous recessiveHeterozygous45

15What is the genotype? CCHomozygous dominantHomozygous recessiveHeterozygous45

16What is the genotype? YyHomozygous dominantHomozygous recessiveHeterozygous45

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Lesson 2A Punnett square is a model used to predict possible genotypes and phenotypes of offspring.

2. How can inheritance be modeled?18Draw the following Punnett Squares

Yy x yyCC x ccYyyyYYyyyyyyCCccCCCCccccGenotype ratio:Genotype ratio:Phenotype ratio:Phenotype ratio:0:2:2 (0:1:1)2:2 (1:1)0:4:0 1:0

19Punnett Square Brain Pop

http://www.goldiesroom.org/Shockwave_Pages/REG-18-tnm--punnettsquares.htm

20Lesson 2A pedigree shows phenotypes of genetically related family members.

femalemaleMalefemaleMaleaffectedFemaleaffected

2. How can inheritance be modeled?21Lesson 2 ComplexSometimes traits appear to be blends of alleles.Complex Patterns of Inheritance

How do some patterns of inheritance differ from Mendels model?

27What color are Mrs. Calderons dads eyes?Mrs. CalderonMrs. Calderons family Pedigree for Blue eyes (bb)BlueDarkCant tell from the chart60

23How many brothers does Mrs. Calderons dad have?Mrs. Calderon1234567890Mrs. Calderons family Pedigree for Blue eyes (bb)60

24Does Mrs. Calderon carry the blue eye gene?Mrs. CalderonYesNoCant tell from the chartMrs. Calderons family Pedigree for Blue eyes (bb)60

25Does Mrs. Calderons mom carry the blue eye gene?Mrs. CalderonYesNoCant tell from the chartMrs. Calderons family Pedigree for Blue eyes (bb)60

26Lesson 2 Complex

How do some patterns of inheritance differ from Mendels model?28

Lesson 2 ComplexIncomplete Dominance: when the offsprings phenotype is a blend of the parents phenotypes.

How do some patterns of inheritance differ from Mendels model?Hair texture29

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Lesson 2 ComplexCodominance occurs when both alleles can be observed in a phenotype.How do some patterns of inheritance differ from Mendels model?

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cattle coat color (key below)CR = red CW = white CWCR or CRCW = roan (where both red and white are expressed

32Lesson 2Polygenic Inheritance: occurs when multiple genes determine the phenotype of a trait (ex: skin color, eye color).How do some patterns of inheritance differ from Mendels model?

33Lesson 2

3. How do some patterns of inheritance differ from Mendels model?

34Eye Color

Two layers to the eye, back and front. Back is blue (this is why babys have blue eyes) the front is controlled by pigment production (Brown/Green) if you have a G then your eyes will create a little pigment in the front layer and you will have green eyes.Example: 3 flasksAdd blue to all flasks2nd flask and a small amount of pigment (yellow) to make green3rd add more pigment to make brownhttp://youtu.be/yVLhDUYH_Dc 35

Lesson 2Multiple alleles: Some traits are determined by more than one allele; ex: Human ABO blood typesHow do some patterns of inheritance differ from Mendels model?

in human blood types there 3 possible alleles for the ABO blood typing systemIA = A antigen IB = B antigeni = no antigen " both IA and IB are dominant over i but," both IA and IB are codominant with each other (that means, they are both expressed equally)

36Lesson 2An organisms environment can affect its phenotype.Some examples of environmental factors that affect phenotype are soil type that a flower is growing in or time of year that a butterfly develops.Genes and the Environment

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What type of inheritance is it when the offsprings phenotype is a blend of the parents phenotypes? Incomplete dominanceCodominanceMultiple allelesPolygenic inheritance45

39What type of inheritance occurs when multiple genes determine the phenotype? Incomplete dominanceCodominanceMultiple allelesPolygenic inheritance45

40What occurs when both alleles can be observed in a phenotype?A.incomplete dominanceB.homozygousC.polygenicD.codominance45

413. All inherited traits follow Mendels patterns of inheritance.TrueFalse45

424.Scientists have tools to predict the form of a trait an offspring might inherit.TrueFalse45

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