O T T F F S S E __ What comes next?

O T T F F S S E __ It’s EASY if you know the PATTERN! (Just like Punnett Squares) NENE WOWO HREEHREE OUR OUR IVEIVE IXIX EVENEVEN IGHTIGHT 9 NINENINE

C HAPTER 11-2: PROBABILITY & PUNNETT SQUARES

Go to Section: Tossing Coins If you toss a coin, what is the probability of getting heads? Tails? If you toss a coin 10 times, how many heads and how many tails would you expect to get? Working with a partner, have one person toss a coin ten times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 10 tosses. Section 11-2 Interest Grabber

Go to Section: Interest Grabber Answers 1.Assuming that you expect 5 heads and 5 tails in 10 tosses, how do the results of your tosses compare? How about the results of your partner’s tosses? How close was each set of results to what was expected? 2.Add your results to those of your partner to produce a total of 20 tosses. Assuming that you expect 10 heads and 10 tails in 20 tosses, how close are these results to what was expected? 3.If you compiled the results for the whole class, what results would you expect? 4.How do the expected results differ from the observed results? Results will vary, but should be close to 5 heads and 5 tails. The results for 20 tosses may be closer to the predicted 10 heads and 10 tails. The results for the entire class should be even closer to the number predicted by the rules of probability. The observed results are usually slightly different from the expected results.

It can be written as a: Fraction ____ Percent ____ Ratio ____ 1/4 25% 1:3 Probability is the likelihood that a particular event will occur.

E X : C OIN FLIP There are 2 possible outcomes: or The chance the coin will land on either one is: ____ ____ ____ 1/250%1:1 Alleles segregate randomly just like a coin flip... So we can use probability to predict outcomes of genetic crosses.

PROBABILITY Past outcomes do not affect future ones. Probability works best predicting a large number of events. The more flips…the closer results will be to the expected 50:50 average. If last coin flip was heads… there is still a 50/50 chance the next flip will be heads too.

Dominant allele is represented by a capital letter. (usually the first letter of the trait) Recessive allele is represented by the SAME lower case letter. Ex: Tall = T Short = t M ENDEL ’ S P RINCIPLE OF DOMINANCE

When both alleles in the pair are the same, the organism is homozygous (purebred/truebred) EX: TT or tt When both alleles in the pair are different, the organism is heterozygous (hybrid) Ex: Tt H OMOZYGOUS VS. HETEROZYGOUS

Genotype: The genetic makeup of an organism Phenotype: The expressed trait of an organism or its appearance. P HENOTYPE VS. GENOTYPE

M ONOHYBRID CROSS : C ROSSING A ONE GENE TRAIT. A Punnett square for a monohybrid cross looks like this:

Punnett squares are used to show possible offspring from a cross between 2 parents. o Parent alleles go at top and on left side o Boxes show possible combinations T TtTt

1. Figure out what parent alleles are 2. Choose correct Punnett square size 3. Put in possible parent gametes 4. Fill in boxes with offspring combinations 5. Determine probabilities of phenotypes & genotypes S TEPS FOR MAKING CROSSES

M ONOHYBRID CROSS IN PEA PLANTS Tall is dominant over short TALL = ____ SHORT = ____ T t Let’s make a cross! PURE TALL pure short X

PURE TALL PARENT W HAT ARE THE PARENT ALLELES ? T T _________   T T HOMOZYGOUS dominant What gametes can it make?

PURE SHORT PARENT W HAT ARE THE PARENT ALLELES ? t t _________   t t Homozygous recessive What gametes can it make?

GENOTYPE _____ PHENOTYPE _______ _____ of the offspring ____ % ___/4 will be tall TT tt T tT tT tT t T tT tT tT t TtTt TALL ALL 100 4

L ET ’ S TRY ANOTHER : H YBRID X H YBRID

HYBRID TALL PARENT W HAT ARE THE PARENT ALLELES ? T t _________   T t HETEROZYGOUS HETEROZYGOUS What gametes can it make?

GENOTYPES ¼ = _____ ½ = _____ ¼ = _____ Tt T t T T tT t T tT t t PHENOTYPES ____ or ____% _________ ____ or ____% _________ TT 75 TtTt tt 3/4 1/4 SHORT TALL 25

PRACTICE MAKING GAMETES FOR A MONOHYBRID CROSS Tall = ____ Round seeds = ___ Short = ____ Wrinkled seeds = ___ T t R r

W HAT ARE THE POSSIBLE GAMETES ? Homozygous Tall parent = What gametes can it produce?   T TT

W HAT ARE THE POSSIBLE GAMETES ? PURE wrinkled parent = What gametes can it produce?   rr rr

W HAT ARE THE POSSIBLE GAMETES ? Heterozygous Round parent = What gametes can it produce?   R r Rr

W HAT ARE THE POSSIBLE GAMETES ? Hybrid Tall parent = What gametes can it produce?   Tt T t

Thomas Hunt Morgan applied Mendel’s principals to fruit flies to see if he would get the same results in an animal.