Non-Mendelian Genetics Part 2: Non-Mendelian Genetics

Last week we learned about Mundelein Genetics This week we will learn about Complex patterns of Inheritance. Complex inheritance-does not follow the patterns that Mendel described. Review the Questions on board over what we did week one, explain that that was complete dominance

Exceptions to Simple Dominance 1. Incomplete dominance 2. Co dominance 3. Multiple alleles 4. Sex-linked

Incomplete dominance- When the heterozygous phenotype is intermediate (mix) between those of the two homozygous parents. Example AA=red Aa=pink aa=white

Incomplete dominance (one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype.) Genotype Phenotype Example Homozygous dominant Dominant Curly hair Heterozygous Intermediate (blend) Wavy hair Homozygous recessive Recessive Straight hair

Practice problem: Incomplete dominance A wildcat comes in three colors, blue, red, and purple. A homozygous (BB) individual is blue, a homozygous (bb) individual is red, and a heterozygous (Bb) individual is purple. What would be the genotypes and phenotypes of the offspring if a blue wildcat were crossed with a red one?

P1 Cross Blue X Red BB X bb F1 Genotype: Phenotype: Key: BB=blue Bb=purple bb=red BB X bb F1 Genotype: Phenotype:

Codominance- both alleles are expressed, neither allele is dominate over the other.

Sickle Cell

Codominance (forms of the gene are equally dominant to each other) Genotype Phenotype Example Homozygous dominant Dominant Red horse hair Heterozygous both Roan hair (red AND white) Homozygous recessive Recessive White horse hair

Practice Problem: Codominance In cattle, reddish coat color is not completely dominant to white coat color. Heterozygous individuals have coats that are roan colored (ie. reddish, but with spots of white hairs). Show a cross of a homozygous dominate red bull to a roan cow. (hint roan is heterozygous)

P1 Cross Red X Roan BB X Bb F1 Genotype: Phenotype: Key: BB= Red Bb= Roan (both of red and white) bb= White BB X Bb F1 Genotype: Phenotype:

Co-Dominance Vs. Incomplete Dominance Make a poster with a fictitious Animal or plant illustrating Co-Dominance and Incomplete Dominance. Give your new organism a name and title your poster “ Complex Inheritance pattern of ___________” Make a “key” with the genotypes and phenotypes listed. List the parents genotype as homozygous and draw a small image of each then draw one heterozygous offspring larger, list the genotype. (see example) List and Define the Vocab word at the bottom of poster Must be COLORED and NEAT!! You may NOT copy my example think of something on your OWN!! End Day whats not done is HW.

Review What is Complete/Simple dominance What is Incomplete Dominance? What's Co dominance? How are they different from each other? How are the different from Complete Dominance?

Can anyone remind me how the law of segregation helps us in making our punnet square? Remember the law of segregation is what tells us we get one allele from each of our parents. Law of Segregation –during meiosis the alleles separate from one another so that each gamete receives one allele

All along we have been talking about traits that have been determined by only two different alleles. Its true each of us have two alleles for each gene, but that there are more than two options for each allele.

Multiple alleles- having more than 2 alleles for a specific trait Remember a gene is a inherited trait (hair color) an allele is a form of that gene that codes for the phenotype (brown, blond, red, etc)

Multiple allele (Multiple alleles can demonstrate a hierarchy of dominance) in this example, there a 4 possible alleles: M, mb , mc , m Genotype Phenotype Example MM, Mmb, Mmc, Mm Dominant to all others Ace beats the King, Queen, Jack mbmb, mbmc, mbm Version b (dominant to mc & m) King beats the Queen & Jack mcmc, mcm Version c (dom. to rec.) Queen beats the Jack mm Recessive to all others Jack there are often hundreds of alleles for any particular gene.

Blood cells are an example of multiple alleles and Co-Dominance As you can count, there are 6 different genotypes & 4 different phenotypes for blood type.

Bottom line for Multiple alleles The presence of multiple alleles allows for an increased number of genotypes and phenotypes, thus creating more variation. Why might variation be a good thing????

Practice Problem: Multiple alleles A woman with Type O blood and a man who is Type AB have are expecting a child.  What are the possible blood types of the kid?

Type O X Type AB This Chart will Always be provided for you

Worksheet Multiple Alleles what’s not done is HW

Sex linked Traits

Male Genotype: XY Female Genotype: XX Sex linked Sex linked traits- characteristic controlled by genes that are on the X chromosome. *Remember* Male Genotype: XY Female Genotype: XX

Sex-linked (traits carried on sex chromosome, usually X-linked) Genotype Phenotype Example XHXH XHY Non-afflicted, not a carrier Normal female Normal male XHXh Carrier but not afflicted Carrier female *males cannot be carriers! XhXh XhY Both are afflicted Colorblind female & male

Why are more males affected by X-linked traits than females?

Why are more males affected by X-linked traits than females? Males have an XY genotype, since males have only one X chromosome, they are affected by recessive X linked traits more often than females. Females have an XX genotype and the other X chromosome would likely mask the recessive trait.

Sex-Linked Traits Can you see a number inside this circle? About 8% of males a color blind and only .5% of females

Punnett Square XB Y XBXB XB Y Xb XBXb Xb Y XB = Normal Xb = affected trait Y= Normal Y chromosome XB Y XBXB XB Y Xb XBXb Xb Y

Practice problem: Sex-linked Hemophilia is due to a sex-linked recessive gene (Xh) and the normal condition to the gene (XH). Show a cross between a hemophiliac man and a woman does not carry the trait.

hemophiliac man X normal woman Key XH = Normal Xh = Hemophiliac *Remember* Male Genotype: XY Female Genotype: XX

Sex linked traits WS what’s not done is HW

Lets review our new terms!! Sex linked traits- characteristic controlled by genes that are on the X chromosome. Incomplete dominance- When the heterozygous phenotype is intermediate between those of the two homozygous parents. Codominance- both alleles are expressed, neither allele is dominate over the other Multiple alleles- having more than 2 alleles for a specific trait