Biology Chapter 11

1. Biology Chapter 11 Introduction to Genetics: Mendel and Meiosis

2. IQ #1 1. How many chromosomes would a sperm or an egg contain if either one resulted from the process of mitosis? 2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo? 3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have?

3. Section 11-4: Meiosis I. MEIOSIS A. Meiosis= process of _________________________ in which the number of chromosomes per cell is cut in 1/2 and the homologous chromosomes that exist in a diploid cell are separated. (and produce haploid cells) B. Purpose= Reduction Division Form gametes (egg and sperm)

4. II. DIPLOID AND HAPLOID CHROMOSOME NUMBER A. During ________________ the genetic material from one parent combines with genetic material from another Example: A fruit fly has 8 chromosomes A set of 4 came from the female fly A set of 4 came from the male fly fertilization B. The two sets of chromosomes are said to be homologous = a female chromosome has a corresponding male chromosome.

5. C. =contain both sets of homologous chromosomes D. = contain 1 set only Male gamete Female gamete Diploid (2n) Haploid (n) Sperm (n) = 23 chromosomes Egg (n) = 23 chromosomes

6. Question: If we start with a diploid cell, how do we get an organism that produces haploid gametes? Answer: Example: what if: Meiosis (aka: reduction division) 1 replication; 2 divisions 8 46 Human Fruit fly 16 92 8 Duplicated chromosomes 46 46 8 Duplicated chromosomes 4 4 4 4 23 23 23 23

7. PROCESS OF MEIOSIS (DIVIDED INTO 2 STAGES: MEIOSIS I & IIINTERPHASE: growth, DNA synthesis, protein production, organelle production A. Meiosis I     1. homologous chromosomes pair up (Form tetrads) 2. nucleoli disappear   3. nucleus disappears 4. crossing-over occurs: portions of chromatids exchange genetic material 2n (diagram 277) prophase I

8. Crossing-Over Crossing Over: exchange of genetic material between homologous chromosomes Go to Section:

9. Crossing Over Go to Section:

10. Crossing Over Crossing-Over Go to Section:

11. metaphase I 1. homologous pairs (tetrads) line up at the equator    2. spindles attach to chromosomes independent assortment occurs anaphase I 1. spindles pull the homologous chromosomes toward opposite ends of the cell Key point: homologous pairs separate, cell now haploid

12. n n Telophase I 1. Nuclear membranes reform 2. cell begins to separate into two new haploid cells     3. 2 haploid daughter cells

13. Figure 11-15 Meiosis Meiosis I Section 11-4 Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

14. Figure 11-15 Meiosis Meiosis I Section 11-4 Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

15. Figure 11-15 Meiosis Meiosis I Section 11-4 Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

16. Figure 11-15 Meiosis Meiosis I Section 11-4 Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

17. B. Meiosis II (similar process as mitosis; no replication) Prophase II Metaphase II Anaphase II Telophase II/ Cytokinesis n n n n ***RESULT: 4 haploid daughters that are genetically different!!

18. Figure 11-17 Meiosis II Meiosis II Prophase II Metaphase II Anaphase II Telophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Go to Section:

19. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II The chromosomes line up in a similar way to the metaphase stage of mitosis. Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Anaphase II Telophase II The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Go to Section:

20. Figure 11-17 Meiosis II Meiosis II Prophase II Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Metaphase II Anaphase II Telophase II The chromosomes line up in a similar way to the metaphase stage of mitosis. The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Go to Section:

21. Figure 11-17 Meiosis II Meiosis II Section 11-4 Prophase II Metaphase II Anaphase II The chromosomes line up in a similar way to the metaphase stage of mitosis. Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. Telophase II The sister chromatids separate and move toward opposite ends of the cell. Meiosis II results in four haploid (N) daughter cells. Go to Section:

22. Figure 11-17 Meiosis II Meiosis II http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html Section 11-4 Prophase II Metaphase II Anaphase II The chromosomes line up in a similar way to the metaphase stage of mitosis. Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original. The sister chromatids separate and move toward opposite ends of the cell. Telophase II Meiosis II results in four haploid (N) daughter cells. Go to Section:

23. IV. GAMETE FORMATION (refer to page 278) A. Males 1. 2. male gametes produced by a process called _________________ B. Females 1. 4 haploid cells are produced but only 1-haploid cell is a 3-produce 2. female gametes produced by a process called _______________ The 4 haploid cells (gametes) = sperm spermatogenesis viable egg polar bodies caused by uneven cytoplasmic division oogenesis

24. Chapter 18 Sexual Reproduction, Meiosis, and Genetic Recombination Figure 18-10 Gamete Formation (a) In the male, all four haploid products of meiosis are retained and differentiate into sperm. (b) In the female, both meiotic divisions are asymmetric, forming one large egg cell and three (in some cases, only two) small cells called polar bodies that do not give rise to functional gametes. Although not indicated here, the mature egg cell has usually grown much larger than the oocyte from which it arose.

25. Mitosis Meiosis Number of daughter cells Type of cells produced Number of divisions Number of replications Purpose of division V. COMPARING MITOSIS AND MEIOSIS A.Mitosis results in the production of two genetically identical diploid cells, whereas meiosis produces four genetically different haploid cells.http://biologyinmotion.com/cell_division/ 4 haploid cells 2 diploid cells Body cells gametes 2 1 1 1 Sexual reproduction Growth, replacement, repair, asexual reproduction

26. Section 11-1 Standards addressed: CA 3.b. Students know the genetic basis for Mendel’s laws of segregation and independent assortment. National 7 2.c. Students know an inherited trait can be determined by one or more genes. 7.2.d. Students know plant and animal cells contain many thousands of different genes and typically have two copies of every gene. The two copies (or alleles) of the gene may or may not be identical, and one may be dominant in determining phenotype while the other is recessive. B1. 2.d. Students know new combinations of alleles may be generated in a zygote through the fusion of male and female gametes (fertilization). Key Ideas: What is the principle of dominance? What happens during segregation?

27. INTRODUCTION TO GENETICS I. The work of Gregor Mendel A. : the scientific study of heredity B. Heredity:  II. Gregor Mendel's Peas A. In the 1800's, _____________________________ (an Austrian Monk) conducted the first scientific study of heredity using pea plants. B. Pea plants contain both male (pollen:sperm) and female (eggs) reproductive parts. Genetics Passing genes from generation to generation Gregor Mendel

28. Flowering Plant Structures: Pea Plant C. _______________ = Joining of male and female reproductive cells Fertilization

29. D. _________________= a pea plant whose pollen fertilizes the egg cells in the very same flower.   1. Mendel discovered that some plants ___________ for certain traits 2. Trait= Example: seed color, plant height 3.True breeding (a.k.a. pure)= Example: Short plants that self pollinate for generations always produce offspring that were pure for shortness. Self-pollination “Bred True” Specific Characteristics Peas that are allowed to self-pollinate produce offspring identical to themselves

30. Cross Pollination Self pollination

31. E. _______________= male sex cells from one flower pollinate a female sex cell on a different flower. Cross-pollination F. Mendel manually cross pollinated pea plants, removing the male parts to ensure no self-pollination would occur. Through a series of experiments, Mendel was able to make discoveries of basic principles of heredity. 1. principle of 2. principle of 3. principle of Dominance Segregation Independent Assortment

32. III. Experiments Mendel performed A.Mendel studied __ different traits in pea plants each with 2 contrasting characters. (refer to page 264) B.Each trait Mendel studied was controlled by one gene. C.Different forms of a gene (trait) = Example: Gene for plant height has 2 alleles 7 Alleles Dominant: T = tall Recessive: t = short

33. Figure 11-3 Mendel’s Seven F1 Crosses on Pea Plants Mendel’s Seven Crosses on Pea Plants Section 11-1 Seed Shape Seed Color Seed Coat Color Pod Shape Pod Color Flower Position Plant Height Round Yellow Gray Smooth Green Axial Tall Wrinkled Green White Constricted Yellow Terminal Short Round Yellow Gray Smooth Green Axial Tall Go to Section:

34. Parent Offspring pure bred tall x pure bred tall TT X TT All plants are pure bred short x pure bred short tt X tt All plants are Pure bred tall x pure bred short X All plants are Mendel Experiment #1: TALL SHORT tt TT TALL

35. Conclusion: genes ·individual factors (now known as _________) ·the factors ________________________________= some alleles are dominant (expressed trait;written as a capital letter; ex. T) some are recessive (hidden/masked trait; written as a lower case letter; ex. t) From these conclusions, Mendel wanted to continue his experiments to see what happened to the recessive trait did not blend Principle of Dominance

36. Principles of Dominance Section 11-1 P Generation F1 Generation F2 Generation Tall Short Tall Tall Tall Tall Tall Short Go to Section:

37. Principles of Dominance Section 11-1 P Generation F1 Generation F2 Generation Tall Short Tall Tall Tall Tall Tall Short Go to Section:

38. Principles of Dominance Section 11-1 P Generation F1 Generation F2 Generation Tall Short Tall Tall Tall Tall Tall Short 3 tall : 1 short Go to Section:

39. Conclusion: ·___________________________: The reappearance of the recessive allele indicated that at some point the allele for shortness separated from the allele for tallness. Mendel suggested that the alleles separated during the formation of the sex cells (gametes)….During meiosis. Principle of Segregation

40.  IV. PROBABILITY AND PUNNETT SQUARES The likelihood that a particular event will occur     A. Probability =      B. Probability= Example #1: If you flip a coin, what is the probability of landing on heads? Probability= (side that has a head on it) ( opportunities on a coin; head or tails) Example #2: If you flip a coin 3 times what is the probability of landing on heads? Probability= # of times a particular event occurs # of opportunities for the event to occur (# of trials) 1 2 2 ½ x ½ x ½ = 1/8

41. A.Each flip is   B.The   C.The principles of probability can be used to independent of the next. Past outcomes do not affect future ones. Similar to alleles that segregate randomly, like a coin flip. larger the number of trials the closer you get to the expected outcomes predict the outcomes of genetic crosses.

42. IV.PUNNETT SQUARES Use of Punnett squares help determine the probable outcomes of genetic crosses. · New vocabulary to help with Punnett squares  -Homozygous =  -Heterozygous= -Genotype= -Phenotype= -Hybrids= Having 2 identical alleles (TT, tt) Having 2 different alleles (Tt) Genetic makeup of an organism (TT, tt, Tt) Physical appearance (tall or short) The offspring resulting from a cross between parents of contrasting traits

43. ·Example of a Punnett square: Parent (P) cross homozygous tall( ) x homozygous short( ) tt TT t t T Tt Tt T Tt Tt F1 offspring Probability of producing homozygous tall offspring? Probability of producing hybrid? 0/4 4/4

44. IV.PROBABILITY AND SEGREGATION • For fun, lets cross F1’s to see if Mendel’s assumptions about segregation are correct: • Tt x Tt T t T TT Tt t tt Tt If the alleles segregate during meiosis, then the probable outcomes will be: TT= Tall= Tt= Short= tt= Ratio tall:short= 1/4 3 2/4 1 3:1 1/4

45. Mendel was correct in his assumptions about Segregration Conclusion: IV.PROBABILITY AND INDEPENDENT ASSORTMENT A.Mendel wondered if one pair of alleles affected the segregation of another pair of alleles.  B.The two factor cross: Mendel crossed RRYY x rryy (P)(aka:two trait cross) All offspring are Do round seeds have to be yellow? Hybrid (RrYy) (F1)

46. A.Then he crossed the hybrids (F1): RrYy x RrYy · Punnett square formatting rules for 2 trait crosses 1. Determine the possible gametes produced by the parents. 2 methods: a.F- RrYy O- I- L- irst two (RY) (Ry) utside two (rY) nside two (ry) ast two

47. a.Use a punnett square. One trait on top and the other trait on the side. Parent 1: RrYy Parent 2: RrYy Y y y Y R RY Ry Ry R RY r ry rY r rY ry Possible gametes Possible gametes

48. 2. Place one parent’s gametes at the top of a 16-Punnett square and the other parent’s gametes on the side of the 16-Punnett square. RY Ry ry rY RRYY RRYy RrYY RrYy RY RRYy RRyy RrYy Rryy Ry rY RrYY rrYy RrYy rrYY rryy rrYy Rryy ry RrYy

49. Section 11-3 Probability: RY (round and yellow)= Ry (round and green = rY (wrinkled and yellow)= ry (wrinkled and green)= Phenotype Ratio=   Conclusion= 9/16 3/16 3/16 1/16 9:3:3:1 Alleles for seed shape independently assort. Go to Section:

50. Independent assortment Genes for different traits can segregate independently during the formation of gametes ****This is true if the traits you are studying Just by chance all 7 of Mendel’s traits were on different chromosomes. are located on different chromosomes