Unit 7 Meiosis and Mendel

1. Quiz Date: Jan. 11 /12 Test Date: Jan. 18/19 Unit 7 Meiosis and Mendel Genetics and Inheritance

2. UNIT 8 - INTRODUCTION TO GENETICS • Although the resemblance between generations of organisms had been noted for thousands of years, it wasn’t until the 1800s that scientific studies were carried out to develop an explanation for this. Today we know that we resemble our parents because of _______________, which is the set of characteristics we receive from ______________________. The study of heredity is known as _________________. heredity our parents genetics

4. I. SEXUAL REPRODUCTION & MEIOSIS (pp. 275-278) • In sexual reproduction, an egg and sperm cell fuse together to create a fertilized egg or _______________. zygote

5. A. Chromosome Number Body 1. Somatic Cells - _____________ cells • Human somatic cells contain ________ chromosomes • ______________ or ________ meaning they contain a ____________ set of chromosomes, half ( _____ ) from _________ and half from ________. • “Matching” chromosomes known as ____________________. • made up of a copy of a chromosome from each parent, with the same ___________, but they are ____________________. • Somatic cells use ___________ for growth, development, renewal, and repair 46 Diploid 2n double 23 Mom Dad Homologous pairs not identical genes mitosis

6. Homologous Chromosomes

7. GAMETES Egg Sperm 2. Gametes - ___________ and _______________ cells • Human gametes contain ______ chromosomes. • ______________ or ______ meaning there is _____ set of instructions for each ______. • When gametes fuse together in _____________________, the ________________ produced is _____________ and has _______ chromosomes. • Gametes are produced by a process called __________, rather than mitosis 23 Haploid n gene one zygote fertilization diploid 46 meiosis

8. Haploid vs. Diploid Karyotypes

10. B.Meiosis • Special type of cell division that only occurs in specialized germ cells (sex cells) in ____________ of females and ______________ of males. • Before meiosis, DNA is replicated once (during ______ phase of ________________)… • …But during meiosis cell divides ________________, resulting in ______ cells with _______ the original chromosome number. • Unlike mitosis which produces identical cells, meiosis produces genetically _____________ cells. ovaries testes S interphase 2X, two times 4 1/2 non-identical

11. Identical somatic cells Unique gametes

12. Meiosis occurs in two stages:

13. 1. Meiosis I • Prophase I • Unlike in prophase of mitosis, In prophase I___________________________ come together and stick to each other to form a ______________. Homologous pairs tetrad

14. Meiosis I Sister chromatid • Crossing Over • Exchange of genetic information between a ________________________________ with its ___________________________________. • Occurs very frequently • Allows for __________________________. Non-sister homologue Genetic variation

15. Meiosis I Metaphase I • _____________________________ align in equator of cell • Each homologue consists of _______________________________________. • Anaphase I • __________________________________________ are pulled apart • _________________, _________________________ still intact Tetrads Two sister chromatids Homologous pairs Centromeres Sister chromatids

17. Meiosis I • Telophase I • Two cells are formed, each with _______ chromosomes • Each chromosome still composed of two ___________________ • Two cells produced at the end of meiosis I are _______________ because______________________ 23 Sister chromatids haploid There are no homologous pairs present

18. MEIOSIS II

19. 2. Meiosis II • Continues with the two cells formed moving directly into prophase II without any further _____________________ of DNA. • In anaphase II, ______________________ are pulled apart. • Two new cells are formed from each of the two cells formed in meiosis I, resulting in a total of ___________new cells, each with ____________the original number of chromosomes. • Cells produced are called ____________________. replication Sister chromatids 4 1/2 Gametes

20. MEIOSIS • In females, process is known as ________________________. • In males, process is known as _________________________. oogenesis spermatogenesis

21. 3. Oogenesis vs. spermatogenesis • Spermatogenesis: Males produce 4 viable sperm cells • Begins: ____________ • Ends: ___________ puberty death

22. 3. Oogenesis vs. spermatogenesis • Oogenesis: Females produce only one egg and 3 polar bodies • Begins: ___________ • Ends: ___________ Before birth menopause

23. II. HISTORY OF GENETICS (pp. 263-270) Genetics • A. Gregor Mendel • Known as the “Father of _______________” • Famous for his experiments with ________ plants. pea

24. Mendel pureline, purebred • Used true-breeding pea plants, which means ________________________; characteristics always show. Known as the ____________ generation. • Studied seven ______________, including plant height, seed color, flower color, etc. • A character is an ______________________________. • A trait is a variant of a character • Example: Eye color is a character, brown eyes or blue eyes are traits P characters Inherited characteristic

25. Mendel • Pea plants cross-pollinate, meaning pollen from one plant fertilizes an egg from another, but they can also self-pollinate, meaningpollen can fertilize egg from ______________ plant. Mendel controlled the fertilization process of the pea plants by preventing __________________________________ and controlling ___________________________________. same Self-pollination Cross-pollination

26. Pea Traits Studied

27. B. Mendel’s Results True-breeding • P generation – Crossed __________________ plants with one trait with ________________ plants with the other. • For example, _____________________________________________ • F1 generation – Offspring produced from _________________. In F1, one trait ____________. For example, tall plants X short plants = __________________________. • F2 generation – Offspring produced from _________________. In F2, trait that disappeared in F1 reappeared in __________ of the offspring; the other ¾ showed _____________________________. True-breeding TT (tall) x tt (short) P X P disappeared All tall plants F1 X F1 1/4 Dominant trait

29. Mendel’s Principles • C. Mendel’s Principles – After analyzing his results carefully, Mendel formed conclusions that increased understanding of inheritance and opened the door for the study of genetics. • Individual units called ___________ determine inheritable characteristics. A gene is a portion of ___________ that codes for a specific ____________. genes DNA trait

30. Alleles and Genes

31. Mendel’s Principles • For each gene, an organism inherits two alleles, one from each __________________. Alleles are different forms or ____________________ of a ___________. For any given trait, • If an organism is ___________________, its alleles are the same and the trait will be expressed. • If the alleles differ, the organism is said to be ___________________ for that character and only one allele will be expressed. The expressed allele is the ______________ allele, designated by an __________-case letter. The allele that is not expressed in a heterozygous trait is _________________, designated by a _____________-case letter. A recessive allele is only expressed when an organism is ________________. parent gene versions homozygous heterozygous dominant upper recessive lower homozygous

32. Mendel’s Principles • Principle of Segregation - In meiosis, the two alleles for a trait segregate (_______________). Each egg or sperm cell receives a copy of one of the two alleles present in the somatic cells of the organism. There is a _________ chance that a copy of that allele will end up in the gamete produced. • Principle of Independent Assortment – The way one pair of alleles segregates has no influence on any other pair of alleles. separate 50%

33. Independent Assortment

35. D. Genetics Terminology Physical • 1. Phenotype - ________________ description of trait; for example, ______________ • 2.Genotype – Genetic make-up of an organism or set of alleles; for example, ____________________. Tall, short TT, Tt, heterozygous, etc..

36. Genetics Terminology • 3. Application of Terminology - If round pea seeds are dominant to wrinkled pea seeds, round is designated _____ and wrinkled is designated ______. • a. Homozygous dominant • Genotype = ________; Phenotype = ________ • b. Heterozygous • Genotype = ________; Phenotype = ________ • c. Homozygous recessive • Genotype = ________; Phenotype = ________ R r RR round round Rr rr wrinkled

38. III. ANALYZING INHERITANCE (pp.135-137) segregation • A. Probability Due to the law of_______________, if you know the genotype of the parents, you can predict the likelihood of a trait occurring in the offspring. Probability can be written 3 ways. The probability of a coin coming up heads after being flipped is (fraction) _____, (ratio) ________, or (percent) _______. 1/2 50% 1:1

39. B. Punnett Squares meiosis • A Punnett square is a tool used to predict the possible outcomes of _______________ and ____________________; in other words, a Punnett square is used to determine the probability of certain traits appearing in offspring. fertilization

40. Punnett Practice Monohybrid crosses A-D • Must have a key • And Cross with • Each problem • For full credit

41. A: Construct a Punnett square to determine the probability of white flowers is a heterozygous purple flower (Pp) is crossed with a homozygous white flower (pp) P=purple, p=white 1. Key:________________________ 2. Cross:________________ Pp X pp P p 50% Probability of White flowers:___________ p p Pp pp Pp pp

42. B: Construct a Punnett square to determine the probability of short pea plants if a homozygous tall plant (TT) is crossed with a heterozygous tall plant (Tt) T=tall, t=short 1. Key:__________________ 2. Cross:________________ TT X Tt T T 0% T t Probability of short pea plants:___________ Probability of tall pea plants:___________ 100% TT TT Tt Tt

43. C: If round peas are dominant over wrinkled peas, make a Punnett square to determined the genotype and phenotype ratios of the offspring if a heterozygous plant is crossed with a homozygous recessive plant R=round, r=wrinkled 1. Key:__________________ 2. Cross:________________ Rr X rr R r RR:Rr:rr 0:2:2 Genotypic ratio:__________________ Phenotypic ratio:_________________ r r Rr rr Rr rr 2:2

44. D: Use a Punnett square to determine the genotype and phenotype ratios of the offspring from a cross between a homozygous dominant yellow pea plant and a homozygous recessive green pea plant Y=yellow, y=green 1. Key:__________________ 2. Cross:________________ YY X yy Y Y YY:Yy:yy 0:4:0 Genotypic ratio:________________ Phenotypic ratio:_________________ y y Yy Yy Yy Yy 4:0

45. Dihybrid crosses The punnett squares we have been doing are known as ____________________ crosses, meaning that only one traits has been considered at a time. In a dihybrid cross, __________ different ______________ on 2 different _____________ are analyzed. monohybrid 2 genes chromosomes

46. Punnett Practice dihybrid crosses A-B • Key • Cross • Punnet square

47. A. Peas homozygous for round shape and heterozygous for color are crossed with heterozygous yellow peas, heterozygous for shape Key: R=round, r=wrinkled Y=yellow, y=green Cross: _____________________ Genotypic ratio:___________________________________________________________ Phenotypic ratio: _____________________________________________________

48. B. Key: G= gray body, g= black body; R=red eyes, r =black eyes Cross: GGRr X Ggrr What are the phenotypes of the parent fruit flies: ___________________________________________________ Genotypic ratio: ___________________________________________________ Phenotypic ratio: _____________________________________________________

49. Incomplete Dominance • Neither allele has “complete” dominance over the other; heterozygous phenotype is a blendof the 2 homozygous phenotypes • Ex: snapdragons R = red W = white RW = pink

50. Incomplete Dominance: cross a pink snapdragon with a white snapdragon 1. Key: _________________________ 2. Cross: ________________________ Phenotypic ratio:___________________ Genotypic ratio:____________________