Genotype of father – BbEe Genotype of mother – bbee Complete this warm-up while I come check your Spongebob sheet! Put the other dihybrid sheet in the INBOX! If you already turned in the Spongebob sheet, I already checked it!!! In polka-dotted monkeys, polka dots (P) are dominant and no dots (p) is recessive. If a heterozygous female mates with a recessive male, what are the chances that their offspring will have polka dots? Suppose that black hair (B) is dominant over blonde hair (b) and brown eyes (E) are dominant over blue eyes (e). The father has black hair (heterozygous) and brown eyes (heterozygous) and the mother has blonde hair and blue eyes. Genotype of father – BbEe Genotype of mother – bbee a. What percent of the offspring will be totally heterozygous (BbEe)? b. What is the phenotypic ratio? c. What percent of the offspring will have blonde hair and blue eyes (bbee)?  

Complex Patterns of Inheritance Exceptions to Mendel’s rules: not simple dominant/recessive inheritance

The phenotype of the heterozygote is INTERMEDIATE. Incomplete Dominance The phenotype of the heterozygote is INTERMEDIATE. Red + White = Pink

Red parent plant R R RR’ R’ White parent plant R’ All pink offspring!

Both alleles are expressed! Codominance Both alleles are expressed! Cross a Brown and White Cow! B=Brown W=White BW=Brown and White

Let’s See if you Understand! A cross between a Dook blue (B) bird and a white (b) bird produces a Carolina blue bird! Is this incomplete dominance or codominance? What are the genotypes of the parent birds? What is the genotype of the Carolina blue offspring? What would be the phenotypic ratio of offspring produced by 2 Carolina blue birds? RR=red hair; WW=white hair; RW=Roan (red and white together) Predict the phenotypic ratios of offspring when a homozygous white cow is crossed with a roan bull

Multiple Alleles When a gene has more than 2 forms of a gene; Example: blood type in humans has 3 alleles Blood Types: A, B, AB, O A and B are codominant O is recessive to both

Type A: has A protein; attacks cells with B protein Type B: has B protein; attacks cells with A protein Type AB: has both proteins A and B; accepts all blood types Type O: has no surface proteins; can be donated to all blood types, but only accepts type O

If you want to know more… http://learn.genetics.utah.edu/content/begin/traits/blood/

Pretend that Brad Pitt is heterozygous for the type B allele and Angelina Jolie is Type O. If they have a child, what are all the possible blood types of their baby? What if he is homozygous for type B?

Warm-Up: For each problem, draw/complete the Punnett square and give the % probability of each blood type (A, B, AB, O) Use a separate sheet of paper! Homozygous A x homozygous B Homozygous A x heterozygous B Homozygous B x AB Type O x Type AB

Sex-Linked Traits Traits that affect genes on the X chromosome Females: XX Males: XY There are X-linked dominant and X-linked recessive traits Males only have to inherit one version for it to show Females can have a copy of the affected allele on 1 X chromosome and NOT have the disorder (carrier) Examples of X-linked Dominant Disorders: Vitamin D Rickets Examples of X-linked Recessive Disorders: Male-Pattern Baldness, Color Blindness, Hemophilia, Duchenne Muscular Dystrophy Baldness

Vitamin D Rickets Vitamin D allows calcium to be absorbed. No calcium absorption = weak, flimsy bones

Are you colorblind??

Duchenne Muscular Dystrophy Lack of dystrophin (protein that builds muscle) Muscle Deterioration, leading to death No cure No known females with DMD Sex-linked recessive

Punnett Squares for the sex-linked trait hemophilia Cross a heterozygous (carrier) female for hemophilia with a normal male: XNXn x XNY N = Normal n = hemophilia

Colorblindness is inherited as a sex-linked recessive disease Colorblindness is inherited as a sex-linked recessive disease. An affected male marries a heterozygous female. Draw a punnett square of the possible offspring. What is the chance that they will have an affected child? Could any of their daughters be affected?

A certain form of muscular dystrophy is inherited as a sex-linked, recessive gene. Jack has muscular dystrophy. Jane, Jack’s wife, is a carrier for muscular dystrophy. What fraction of their daughters would you expect to have muscular dystrophy? Sons?

Warm-up! In a cross between a pure bred, red-eyed female fruit fly and a white-eyed male, what percent of the male offspring will have white eyes? (white eyes are X-linked recessive) 100% 75% 50% 25% 0% A white-eyed female fruit fly is crossed with a red-eyed male. Red eyes are X-linked dominant. What are the expected phenotypes of the offspring?

Polygenic Traits Trait controlled by two or more GENES (not alleles) AaBbCc x AaBbCc Skin Pigmentation Gene to make melanin Gene to bring nutrients to melanin-producing cells (melanocytes) Gene to turn on/off melanin when in continued presence of UV light Traits vary along a bell curve http://waynesword.palomar.edu/lmexer5.htm