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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.
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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.
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 a time? (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, Outer Inner, 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.
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