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Genetics II Modes of Complex Inheritances and Pedigrees Nancy Dow Jill Hansen Tammy Stundon February 23, 2013 Gulf Coast State CollegePanhandle Area Educational Consortium 5230 West Highway 98753 West Boulevard Panama City, Florida 32401Chipley, Florida 32428 850-769-1551877-873-7232 www.gulfcoast.edu Biology Partnership (A Teacher Quality Grant)

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Pre-test Q and A board Was Mendel wrong? Why arent humans as simple as tall or short? Why are most colorblind people males?

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B ENCHMARK SC.912.L.16.2* Discuss observed inheritance patterns caused by various modes of inheritance, including dominant & recessive which are simple inheritance & codominant, sex-linked, polygenic, and multiple alleles (complex inheritance). (HIGH) Florida Next Generation Sunshine State Standards

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Benchmark Clarifications Students will identify, analyze, and/or predict inheritance patterns caused by various modes of inheritance. Content Limits Items referring to general dominant and recessive traits may address but will not assess the P and F1 generations. Items addressing dihybrid crosses or patterns that include codominance, incomplete dominance, multiple alleles, sex- linkage, or polygenic inheritance may assess the P and F1 generations

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Florida Next Generation Sunshine State Standards Stimulus Attributes Inheritance outcomes may be expressed in percent, ratios, or fractions. Scenarios may refer to codominance or incomplete dominance but not both codominance and incomplete dominance. Punnett squares may be used to predict outcomes of a cross. Response Attribute Options may include codominance or incomplete dominance but not both.

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Mendels Results CharacterDominant x RecessiveF1F1 F 2 Generation Dominant Form: Recessive Form Ratio Flower Color purple x whiteall purple 705 purple: 224 white2.96 Seed Coloryellow x greenall yellow 6022 yellow: 2001 green3.01 Seed Shaperound x wrinkledall round5474 round: 1850 wrinkled2.96 Pod Color green x yellowall green428 green: 152 yellow2.82 Pod Shapeinflated x pinchedall inflated 882 inflated: 299 pinched2.95 Flower Position axial x terminalall axial651 axial: 207 terminal3.14 Plant Height tall x shortall tall787 tall: 277 short2.84

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Ways to inherit traits Simple inheritance the present of a dominant or two recessive alleles will express the trait Dominant simple Recessive simple Sex-linked (x-linked) where the 23 rd chromosome work on different rules Complex inheritance the most common Multiple Allele Co-dominance Polygenetic inheritance Incomplete dominance

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Simple inheritance (single gene) 1. Dominant Inheritance Rr or RR Traits include widows peak, hitchhikers thumb, etc.. Capital letter = Dominant trait When just one dominant gene is present, the trait will be shown Two dominant alleles does not enhance the trait For a recessive trait to be expressed both parents MUST pass on the recessive allele for this trait to be present Which genotype would be the carrier for the recessive trait?

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EXAMPLES OF SINGLE-GENE TRAITS Widows peak is Dominant Straight hairline is recessive Tongue rolling is Dominant Not able to roll the tongue is recessive Regular thumb is Dominant Hitchhikers is recessive Six digits (D)

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EXAMPLES OF SINGLE-GENE TRAITS Cleft chin = rNon-cleft chin =D Unattached earlobes = D Attached earlobes = r Autosomal Simple Inheritance lab

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Simple Dominant Inheritance Disease Huntingtons Disease Chromosome #4; gene makes the brain cells to basically commit suicide neurological spasms, mental problems, motor function problems no treatment CAG is repeated too many times; the number of repeats predicts the age of onset; 40 reps = late middle age

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Carriers Only the genotype Ff is considered to be a carrier If (F) = freckles, what is this persons phenotype? What type of simple inheritance are they expressing? Effect if this was a disorder and not a trait? Why wouldnt the other simple inheritance genotype be considered as a carrier?

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Simple inheritance (single gene) 2. Recessive Inheritance rr Disorders Tay-sachs Jewish, C#15 Cystic Fibrosis Caucasians, C#7 PKU C#12, metabolic disorder Why certain disorders have appeared?....... Lack of genetic variation ? Adaptation?

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A SINGLE BAD GENE WHICH WILL NOT PRODUCE THE ENZYME TO CONVERT PHENYLALANINE TO TYROSINE (BOTH AMINO ACIDS). THIS CAUSES A CONDITION CALLED PKU. THIS CAN CAUSE A BUILD- UP OF PHENYLALANINE IN THE BRAIN WHICH CAN CAUSE MENTAL RETARDATION---CAN BE TREATED WITH DIET AVOIDING THIS AMINO ACID.

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Higher order thinking questions! They have to know what type of inheritance the disorder is in order to answer the question (by either doing a Punnett square or pedigree.) Many test bank questions will indicate the inheritance of a trait; Freckles are dominant. Why cover disorders?

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Human Autosomal Trait Lab Refer to the slides with the simple inheritance traits!

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Mendelian genetics describes inheritance patterns based on complete dominance or recessiveness. There are other types of inheritance that Mendel never considered: Incomplete Inheritance Codominance Multiple Alleles Polygenic Traits Sex-linked Non-Mendelian Genetics

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The relationship between genotype and phenotype is rarely simple

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Many researchers have encountered exceptions to Mendelian Principles so was he wrong? Majority of heritable characters not as simple as peas Phenotypes affected by: many alleles or many genes, environmental factors, sex chromosomes, etc. Non-Mendelian Genetics

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Phenotype can depend on interactions of alleles. In incomplete dominance, neither allele is completely dominant nor completely recessive. Heterozygous phenotype is intermediate between the two homozygous phenotypes Homozygous parental phenotypes not seen in F 1 offspring

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Incomplete Dominance If you cross a RED flower with a WHITE flower, you will get a PINK flower. NOTICE: the RED genotype is RR the WHITE genotype is WW the PINK genotype is RW INcomplete is INbetween If this was blended inheritance pink pink would only make what?

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Lets Practice! Cross a BLACK chicken (BB) with a WHITE chicken (WW). These alleles show INCOMPLETE DOMINANCE BB W W BW What percent is black? White? Gray? Black: 0% White: 0% Gray: 100%

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Cross a BLACK chicken (BB) with a WHITE chicken (WW). These alleles show INCOMPLETE DOMINANCE BB W W BW Genotype: BW Phenotype: Gray What is the genotype and phenotype of the F1 generation? Lets Practice!

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What would the cross look like if you crossed two GREY chickens (BW). These alleles show INCOMPLETE DOMINANCE. BW B W BBBW WWBW Genotype: 1 BB 1 WW 2 BW Phenotype: 1 Black 1 White 2 Gray What is the genotype and phenotype of the F2 generation? Lets Practice! PTC Testers

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CoDominance Both traits are dominant, and show up in the phenotype together. Co means together Black Cow X White Cow = Spotted Cow (BB) (WW) (BW)

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Both alleles are expressed in the heterozygous condition Both alleles contribute to the phenotype. For Example: In chickens, the allele for black feathers is co- dominant with the allele for white feathers. These chickens will have BOTH black and white feathers. COdominant alleles COllaborate together CoDominance

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Cross a Black chicken (BB) with a White chicken (WW). These alleles show CO-DOMINANCE. BB W W BW How many chickens in the F1 generation are completely black? White? Black and white? Black: 0% White: 0% Both: 100% Lets Practice!

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Cross a Black chicken (BB) with a White chicken (WW). These alleles show CO-DOMINANCE. BB W W BW What is the genotype and phenotype of the F1 generation? Genotype: BW Phenotype: Black and white or checkered. Lets Practice!

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Cross two Black and White (checkered) chickens (BW). These alleles show CO-DOMINANCE BW W B WW BW BB List all possible genotypes and phenotypes of the F2 generation. Genotype: 1 BB 1 WW 2 BW Phenotype: 1 Black 1 White 2 Checkered Lets Practice!

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Blood type displays both co-dominance and complete dominance Blood types are different based on the presence or absence of certain antigens on the red blood cells (RBCs) The presence of a antigen (I) is dominant to the absence of an antigen (i). There are two types of antigens that may exist on the surface of RBCs called A (I A ) and B (I B ). Cell surface antigens A and B are codominant, which means they could also show up at the same time on an RBC.

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Matching compatible blood groups is critical for blood transfusions because a person produces antibodies against foreign blood factors. Blood type displays both co-dominance and complete dominance

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Blood type also demonstrates inheritance through multiple alleles Multiple alleles: When more than 2 varieties exist in a trait. In this case, blood can be A/B/O

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Multiple AllelesABO Blood Groups Possible alleles from female Possible alleles from male IAIA IBIB i IAIA IAIAIAIA IAIAIAIA IAiIAi IBIB IAIBIAIB IBIBIBIB IBiIBi iIAiIAiIBiIBiii Blood Types AABBO At any one time, a parent can only have TWO alleles for blood

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The Genetics of Blood Lab

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The inheritance pattern is controlled by two or more genes (each with two alleles) Order of dominance: brown/amber > green/hazel > gray/blue. Polygenic Inheritance At the present, three gene pairs controlling human eye color are known (two on chromosome 15 and one on pair 19).

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Two or more genes work together to create a single phenotype Example: Height is controlled by anywhere from 7 20 different genes (and the environment!) Polygenic Inheritance Wilt Chamberlin stood 71 tall, neither of his parents was over 59 Creates a bell curve distribution

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Polygenic Inheritance Activity Skin color is determined by (at least) 3 genes. Imagine that each gene has two alleles, one light and one dark, that demonstrate incomplete dominance. An AABBCC individual is dark and aabbcc is light. Polygenic Inheritance

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Sex Linked Traits When a trait is carried on the X or Y chromosomes, it is called a sex-linked trait These not only carry the genes that determine male and female traits but also those for some other characteristics as well Dont confuse this with linked genes = when 2 genes are on the same chromosome

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Gene that controls this is on the X chromosome Who is more likely to be color blind men or women? Men: only 1 X chromosome If they have the recessive allele they dont have another X to make up for it. Sex Linked Traits Red Green Color Blindness

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Sex Linked Traits If there is not a normal gene present to offset the defective, recessive gene, the disorder will be present.

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Gene linkage was explained through fruit flies Attention to detail, accurate lab records were critical Different than sex influenced genes

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Females can carry sex-linked disorders. Males (XY) express all of their sex linked genes. Expression of the disorder depends on which parent carries the allele and the sex of the child. X Y

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Question: If a normal male (do those even exist?) has a child with a woman who carries the blindness allele, what are the chances that their children will be colorblind? Will any children be carriers of the trait? XY XcXc X XX c XX X c Y XY

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Pedigrees A diagram that traces the inheritance of a particular trait through several generations.

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Chart showing the genetic connections among individuals in a family Especially useful in following recessive alleles that are not visible in the heterozygote Pedigrees

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Royal Pedigrees Im my own grandpa Royal Pedigrees

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The environment interacts with genotype. Height is a example of a phenotype strongly affected by the environment. diet/exercise sunlight/water (if youre a plant) Phenotype is a combination of genotype and environment. Nature vs. Nurture Virtually all human diseases have some genetic component

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15 minutes!!

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Eye Color and Polygenic Inheritance/Pedigree Lab

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Follow up Q & A Post Test

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Everything Mendel Didnt KnowEverything Mendel Didnt Know a review of the more complex inheritance patterns The Ghost in Your GenesThe Ghost in Your Genes a video with a focus on epigenetics, it should prompt some discussion. Eye Color and GenesEye Color and Genes a simple visual for the variety of melanin present in eye colors