Logic Problem:

• You have 4 cards (on next slide) and need to make as many combinations of them as possible.

• Each resulting combination must have one king and one queen.

One of these: One of these:

How many did you get?

Single Factor Punnetts

• We know how to cross one trait in a Punnett square. (ex. Tall plants x short plants)TT x tt

• What do we do if we want to cross more than one trait at atime? (ex. roundness AND pea color)

Bigger Punnett Squares:•Instead of having only 4 boxes to fill out for 1 trait, now we’ll have 16 boxes for 2 traits.

•How many boxes for 3 traits?

•We need to put the letters on the top and side of the Punnett square, just like a single, normal one!

•How do we do that?

FOIL (like in math class!)

Simplify this equation: (x + 2)(x + 3)First, OuterInner, Last

Now do the same for RrYy.

Each result must have one of each letter.

RrYy x RrYy •Each parent’s gametes must include both roundness and pea color.

•Hint: Draw a circle around the genotypes for roundness and a square around the genotypes for color.

•Use arrows to combine gametes for each box on the top and side.

•There should be one of each letter above the top boxes and one of each on the left of the boxes.

Filling out the Punnett• Complete the cross for RrYy x RrYy. • Each box should have 4 letters in it…two for roundness

and two for color.• Find your four possible phenotypes. (round and yellow,

round and green…)• Determine the genotypes to look for for each

phenotype. (RR/Rr YY/Yy)• Search through your Punnett to find the numbers of

each.• Check on page 271 of your textbook to see if you were

correct!

Independent Assortment

• Genes for different traits can segregate (or assort) independently during the formation of gametes. • Just because you got your brown eyes from your mom,

doesn’t mean you also have to get her blond hair!

• This adds to genetic variation in offspring!

Summary of Mendel’s Principles• Inheritance is determined by genes passed down from parents

to their offspring.

• Some alleles (forms of genes) are dominant while some are recessive.

• Each parent has two copies of a gene. These genes are segregated from each other when gametes form.

• Alleles for different genes can segregate independently from each other.

Homework

• Problems 10, 11, and 13• Rabbit worksheet