General Biology 2

2. General Biology 2 A. Roll B. Personal Introduction C. Statement about disabilities D. Course Policies and Schedule E. Class room management 1. cell phones 2. timeliness 3. questions

3. I. Brief review of meiosis-corner stone of Mendelian genetics • A. Relevant terms to be used • 1. diploid vs. haploid • 2. chromosome versus chromatin • 3. chromatid, monad, dyad, tetrad • 4. homologous chromosomes • 5. synapsis and chiasmata

4. B. Events of meiosis I • 1. prophase I • 2. metaphase I • 3. anaphase I • 4. telophase I

5. C. Interkinesis • 1. some textbooks call this interphase II • 2. lousy name • 3. no DNA replication • 4. pretty much resting stage • 5. some species meiosis is arrested at this stage • 6. human egg is released after meiosis I and meiosis II does not occur unless fertilization happens

6. D. Meiosis II • 1. prophase II • 2. metaphase II • 3. anaphase II • 4. telophase II

7. Biology Happens Around the World

8. II. Early Mendel • A. Biography • 1. 1822-1883 • 2. Moravia-Silesia • 3. 1851-1853 Univ of Vienna • 4. age 29 years • 5. left after two years-epilepsy • 6. entered monastery-safe environment for health reasons • 7. first organism honey bee-practical application • German and italian races

9. B. Qualities of pea plant • 1. who pollinates this flower? • 2. arrangement of petals promotes self-pollination • 3. usually true breeding

10. 4. true breeding = homozygous • 5. easily recognized traits • 6. distinct traits-not intermediate phenotypes • 7. easy to generate large numbers • 8. short generation time • 9. can easily manipulate flowers breeding partners

11. C. Not first to study genetics • 1. earlier geneticists studied multiple traits at one time • 2. did not look at large numbers • 3. did not choose traits that had distinct forms • 4. did not follow through successive generations • 5. predominant conclusions of time-blending theory of inheritance-fusion of inheritance particles • -some factor from male and female mix -analogous to mixing paints -would result in identical offspring -not true

12. III. Mendel’s first cross • Tall vs. short 1. parental generation 2. next generation all tall 3. allowed self-pollination 4. mixed bag 787 tall: 277 short 5. allowed this generation to self pollinate 6. all short true breeding 7. 1/3 tall true breeding-2/3’s of tall were not true breeding

13. B. Explanation • 1. Law of particulate inheritance • a. Each trait or characteristic is influenced by two particles or factors • b. One particle/factor comes from dad and one from mom • c. Particles remain separate and distinct in cells of offspring

14. 2. Law of segregation • a. Independent factors separate during gamete formation • b. These factors come in more than one flavor-one factor may overshadow the second • c. Each gamete receives one of the two factors that an individual carries in its cells • d. Mendel knew nothing of chromosomes or of meiosis

15. C. Mendel’s cross with traits on chromosomes • 1. Parental generation forming offspring of first generation

16. 2. First generation meiosis • Notice separation of factors influencing height in gametes • Basically two flavors of gametes being produced

17. 3. Punnett square for second generation • a. Notice outcome of random mating/self pollination • b. All of short plants will be true breeding • c. 1/3 of tall will be true breeding • d. 2/3’s of tall will produce a mixture as their parents did

18. Vocabulary of monohybrid cross • 1. gene • 2. allele • 3. dominant vs. recessive • 4. phenotype vs. genotype • 5. heterozygous vs. homozygous • 6. monohybrid vs. dihybrid • 7. P, F1, and F2

19. E. Sample problem • In humans, freckles are dominant to no freckles. Mary, who has no freckles, is planning on having children with Paul. Paul, who has freckles, was born to a freckless woman. Mary wants to know the probability of her in utero son has of having freckles. • How do we start? • List the symbols to be used to represent the alleles. • What is the mother’s phenotype? Genotype? • What is the father’s phenotype? What does his genotype have to be? • What alleles are carried in the eggs and sperm of the couple? • Create the punnett square. • What will be the name of the son which is not born yet?

20. F. An analysis of Mendelian ratios • 1. ratios almost too good • 2. discussion in the literature that the numbers should not come out as closely to theoretical as they do • 3. statistical probability of such a good fit is low • 4. other writers come to his defense • 5. will see other results that look very close when we get to the dihybrid crosses.

21. G. Generalizations about Mendelian monohybrid crosses. • 1. three crosses to remember • 2. hetero X hetero • 3. hetero X homo rec • 4. hetero X homo dom

22. H. Chi square analysis • 1. in lab you are going to play Mendel counting the number of kernels of corn that display certain phenotypic ratios • 2. trying to verify Mendelian theoretical ratios • 3. doubtful that you will come as close as Mendel did in your actual ratios • 4. when will close enough be considered close enough to agree with theory • 5. need a statistical test to decide • 6. the statistical test needs to be tied to sample size

23. 7. Background information • tossing a coin 100 times • Expect to get 50:50 • Not going to happen very often • There will be chance variation • How close to predicted results do the actual results have to be to accept that the coin is behaving as you predicted • Is 70:30 close enough or do you need 60:40 • Imagine doing the coin tossings is sets of 100 • The ratios obtained will vary around the 50:50 expected

24. 7. Background information continued • i. one set of tosses by chance alone might come out with 80:20 • j. It is not mathematically impossible that this would happen • k. if this result occurred of 80:20 occurred 1/10th of the time, it would be more significant than if it occurred 1/20th of the time • l. in the first case we might have doubt about the coin itself • m. 1/20 or .05 is where we draw our mathematical line between models that fit theoretical predictions and models that don’t • n. the number of .05 has to do with the number of “experiments” and means that one time out of twenty the experiment will not turn out as predicted by the hypothesis-the results will vary by chance alone

25. 8. Example • a. case one 40 tosses 30T:10H • b. case two 200 tosses 90T:110H • c. each case has a deviation of ten from expected • d. more acceptable in the second case due to sample size • e. chi square test determines the level of acceptability of results • f. chi square = (obs-exp)2/ exp

26. 9. Chi square calculations

27. 10. Compare values to chi square table • a. case one chi square value = 10 • b. case two chi square value = 2

28. I. Test Cross-allows determination of an unknown genotype • 1. You are a breeder of beagles. Barking in beagles is a highly prized trait and is dominant over nonbarking. • 2. Neighbor has a beautiful beagle, but wants to get rid of animal due to a nasty habit • 3. You own a beagle kennel-but don’t know if you want to allow the neighbor’s beagle into your breeding stock • 4. Don’t know his background-where he came from • 5. Perform a test cross • Unknown genotype X homo. recessive

29. J. Intermediate inheritance/incomplete dominance • 1. Not all traits are inherited in Mendelian simple dominance/recessive fashion • 2. In some cases the hybrid heterozygote shows an intermediate phenotype between the two extremes • 3. Don’t confuse this with blending • 4. Example of red and white four o’clock flowers • 5. Heterozygote is pink • 6. What would you expect if two pink four o’clock flowers had offspring?