Example: TtRr X TtRr What is the probability of getting a short smooth offspring? Short? Smooth?

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1 ! Rule of Multiplication (aka Product Rule) how do we determine the chance that two or more independent events will occur together in a specific combination? Example: TtRr X TtRr What is the probability of getting a short smooth offspring? Short? Smooth?

2 ! The probability of getting a tall offspring is! The probability of getting a wrinkled offspring is! The probability of getting a tall wrinkled offspring is:! This is how scientists would determine the probabilities for trihybrid crosses and bigger:! (TtrrGG X TtRrgg)

3 Example:TtrrGG X TtRrgg What is the probability that you would get a Tall plant with Wrinkled Green seeds? T s = Tt X Tt = R s = rr X Rr = G s = GG x gg = Product is:

4 Codominance both alleles are expressed when a heterozygous genotype is present 1. Co means with, together, jointly 2. Black chicken (BB) x White chicken (bb) 100% Black and white checkered chicken (Bb) (some feathers are black and some are white)

5 Multiple Alleles 1. when a trait has more than 2 alleles 2. each organism still ends up with 2 alleles, but there are more alleles to choose from 3. Blood type there are three alleles: i O I A I B Phenotype Type O Type A Type B Type AB Genotype i O i O I A I A or I A i O I B I B or I B i O I A I B (This is an example of codominance as well.)

6 Pleiotropy 1. When a single gene controls more than one phenotypic characteristic 2. Cystic fibrosis and sickle cell disease in each, one gene has multiple effects

7 Polygenic inheritance 1. The additive effects of two or more genes on a single phenotypic character. 2. Examples: human skin color and height

8 ! When a gene hides, interferes with, or prevents expression of another gene! Example: Labrador retriever coat color is coded for by 2 genes: B codes for black, b codes for brown E codes for not yellow and e codes for yellow BBee and bbee and Bbe all give yellow hair. The yellow gene keeps the brown or black proteins from being made.

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12 !! Statistical test that compares the result you got with the ratios you expected Based on sample size with 1000 flips of a coin you are likely to be closer to 50% heads and tails than with only 10 flips

13 ! Use the formula to get a number! Compare that number to a standard chart! Chart tells you whether the difference between what happened and what you expected to happen could be due to chance

14 !! If the chart says difference from what you expected is not due to chance, you know there is something else going on Also called goodness of fit test how well does the data fit what s expected?

15 ! Use the following equation:

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18 ! We would use Chi Square of course!! To use it, we would have to toss the Super Bowl coin many times and record the results.! We would also need to determine the expected numbers.

19 Let s say we tossed the Super Bowl coin 1,000 times.! Results: 395 heads, 605 tails! Could the difference be due to chance or is there something fishy going on?

20 We would expect 1000 tosses to give us 500 heads and 500 tails.

21 ! The number to compare with the chart is X 2! X 2 = (observed heads-expected) 2 + expected (observed tails-expected) 2 expected = ( ) 2 ( ) = = 44.1

22 Compare the numbers above with is bigger than any of the numbers. That means there is less than a possibility that the Super Bowl coins heads and tails were so far from expected JUST BY CHANCE!

23 ! But if we had gotten 505 heads and 495 tails with the Super Bowl coin, our X 2 would equal 0.1.! That is much smaller than any of the numbers on the chart.! This means there is a very good chance that the difference between actual and expected is due to randomness and we shouldn t accuse anyone of trickery.

24 ! Pleiotropy! Polygenic inheritance! Epistasis Plus LINKAGE GROUPS and CROSSING OVER

25 ! Genes on the same chromosome are said to be linked! All the genes on a single chromosome make up a linkage group

26 ! Because they sort together, linked genes do not follow Mendel s Law of Independent Assortment! So you would expect 2 linked genes to always sort out together -- in the case below, getting A always means getting B

27 ! But crossing over means that every so often linked genes are split up and they sort out differently! Scientists can use this phenomena to map how far apart 2 genes are: Those further apart are split up more often than those close together.