Non-Mendelian Genetics

Non-Mendelian Genetics Inheritance patterns that are neither dominant nor recessive

Do Now: Take out homework. Then…clear desks. • Homework: finish practice sheets

Genetics: Dihybrid Crosses BbHh X bbhh (parents) • What gametes will each parent produce? • What will be the genotypes of their offspring? • What would be the phenotypes?

Easter Egg Genetics • PP=purple • pp=pink • Pp=orange • BB=blue • bb=yellow • Bb=green • Bp=red • BP=white • Pb=yellow spotted • bp=white spotted • Black=genetic mutation!!! An egg may be all purple, so it was PP crossed with PP. Or it may be orange and pink, meaning it was Ppxpp.

In Mendelian genetics (Complete dominance), there are only two possible phenotypes: dominant or recessive • Tall plant X Short plant = Tall plant (TT) (tt) (Tt)

But, not all inheritance is based on the rules of Complete Dominance!!

Other inheritance patterns include: • Incomplete Inheritance • Codominance • Multiple Alleles • Polygenic Traits • Sex-linked

1. Incomplete Inheritance: Blending traits • Neither trait is dominant • Hybrids BLEND to make a medium phenotype Red Flower X White Flower = Pink (RR) (WW) (RW)

Incomplete Inheritance Problem • What is the probability of pink flowers if pink flowers are bred with red flowers? R R 50% chance of Pink Flowers R RR RR W RW RW

2. CoDominance: Traits show up together as spots or stripes • Co = together • Black Cow X White Cow = SpottedCow (BB) (WW) (BW)

CoDominance Problem • What are all the possible phenotypes when two spotted cows are bred? B W Possible phenotypes are a black cow, 2 spotted cows, and a white cow B BB BW W BW WW

Below are imaginary organisms. Note horn shape, leg length, fur color and tail shape. Now determine the type of inheritance of the four traits by examining the genotypes of the parents and offspring.

3. Multiple Alleles: More than 2 types of alleles exist for a trait Rabbits have more than 144 alleles for coat color!

The same allele can be dominant or recessive depending on context: agouti > black > albino What will offspring look like if a heterozygous agouti/black rabbit was crossed with an albino rabbit?

Blood type is determined by Multiple alleles and Co-dominance • People have different blood types because of different carbohydrates on their surface.

Blood Type Inheritance Rules: • A person with the IA allele will have A carbohydrates. • A person with the IB allele will have B carbohydrates. • A person with the recessive i allele will have no carbohydrates. • Or a person with both IA and IB alleles will have both A and B carbohydrates on their cells.

Blood Type Problems If a woman with AB blood has children with a man who has type O, what will be the possible genotypes of their children? What will be their blood types? IA IB i IA i IB i i IA i IB i

Ever wonder why there are ranges of skin colors, or eye colors, or hair colors, or height?

4. Polygenic Traits: Require the interpretation of many genes

Parents: Ll Mm Nn X Ll Mm Nn This child received mostly dominant genes This child received mostly recessive genes This also explains why a couple with heterozygous genes can have children who look so different.

Why are some traits like color-blindness, ALD and hemophilia found mostly in boys?

5. Sex-linked: genes are found on the sex chromosomes (X or Y) • Most of these traits are recessive, the normal gene is dominant

Sex-linked inheritance rules • Heterozygous Females (XXc) are carriers. They do not show the trait, but carry a gene for the trait. • Homozygous Females (XcXc) have the trait • Males with the gene (XcY) have the trait.—They do not have another X to counterbalance the affected gene

If a heterozgous woman with normal vision has children with a man who is colorblind, what are the chances that their children will be colorblind? Will any children be carriers of the trait? Xc Y Y X XY XXc XY Xc XcY XcXc XcY

Non-Mendelian Genetics