Review: Dominant/Recessive A dominant allele is capable of masking, or covering up, a recessive allele. PP = purple Pp = purple pp = white This slide hidden. Not strictly necessary. But if you think your students could use some more practice, un-hide it.

Review: Dominant/Recessive In pea plants, purple flowers (P) are dominant over white flowers (p). Show the potential offspring between two heterozygous plants. P p GENOTYPES: P p PP Pp PP: 25% Pp: 50% pp: 25% This slide hidden. Not strictly necessary. But if you think your students could use some more practice, un-hide it. Pp pp PHENOTYPES: Purple: 75% White: 25%

Agenda Notes Coin flipping!!!! Worksheet Exit slip Homework: Worksheet Reminders: Make up test by Friday OR it is a ZERO

Incomplete Dominance Key Point #1: In incomplete dominance, one allele does not mask the other. In heterozygotes, the dominant and recessive alleles BLEND TOGETHER. Example: In snapdragon flowers, red (r) and white (w) are incompletely dominant. During this slide, early finishers should get whiteboards + markers for their tables.

Incomplete Dominance Genotype Phenotype rr (homozygous red) red rw (heterozygous) pink ww (homozygous white) white

Incomplete Dominance

Incomplete Dominance rr rw ww

In carnations (a type of flower), color is an incompletely dominant trait. Red (r) is NOT dominant over white (w). Create a Punnett square showing the potential offspring of two heterozygous carnations. Heterozygous= DIFFERENT Parent 1: rw Parent 2: rw

Incomplete Dominance w r r r r w r r w w w w

Co-Dominance AA = normal cells SS = sickle cells AS = half of each Key Point #1: In co-dominance, both alleles are dominant. In heterozygotes, both alleles are expressed EQUALLY. NOTICE – ALL GENOTYPES HAVE CAPITAL LETTERS BECAUSE ALL TRAITS ARE DOMINANT, NOTHING IS RECESSIVE! Example: Sickle cell anemia in humans AA = normal cells SS = sickle cells AS = half of each

CO-DOMINANCE This is the ONLY kind of inheritance where you use two DIFFERENT CAPITAL letters!!!!!!!!

Sickle Cell Anemia

Sickle cells easily get stuck in the circulatory system.

Sickle Cell Anemia A S A A AA AA AS AS GENOTYPES: PHENOTYPES: AA: 50% Being normal (A) and having sickle cell anemia (S) are co-dominant. Show the potential offspring of a normal father and a heterozygous mother. Fill in percents for genotype and phenotype. A A GENOTYPES: AA: 50% AS: 50% SS: 0% A S AA AA PHENOTYPES: AS AS Normal: 50% Some normal, some sickle: 50% Sickle Cell: 0%

GP 4 GENOTYPES: PHENOTYPES: In cows, color is co-dominant. Show the potential offspring between a red bull (RR) and a white cow (WW). Fill in percents for genotype and phenotype. GENOTYPES: PHENOTYPES:

Codominance ROAN COW RED COW

If you’re a little confused Some ways you can remember… If you’re not confused then you don’t have to listen

Regular dominance

Incomplete dominance- blend! You can have the banana smoothie! Banana and ice cream together!

Co-Dominance: Both at once! The banana split! Banana AND ice cream in one bowl. Separate but together!!!!

Practice Which type, Mendelian (normal), incomplete domianance, or codominance? Rats can be white or have color. If you mate a homozygous dominant brown mouse with a white mouse, you get all brown mice. A man with green eyes and a woman with brown eyes have a baby. The baby has eyes that are brown with bits of green in them. In rabbits, if the genotype is bb it is black, ww is white and bw is grey.

End of class In your folder Grade sheet Quiz Independent practice Widget Planning Exit slip Homework: Lion King Worksheet!!!!!