1. Cell Division Sexual Reproduction = egg & sperm OR Asexual Reproduction = single parent, no egg/sperm Cell Division: reproduction of cells; “cells come from cells” * Basis of all life 2 Main Roles: 1) development of fertilized egg 2) continuation of life (growth, repair)

2. Prokaryotes = binary fission (split in half) OR Eukaryotes = more complex; more genetic material chromosome: structure which contains DNA (deoxyribonucleic acid) chromatin: long, thin fibers of DNA & protein clumping together to form chromosomes

4. gene: specific region of DNA on chromosomes somatic cell: all body cells except egg & sperm; contain chromosomes (humans= 46) Human egg & sperm (gametes) have 23 chromosomes Prior to Cell Division… * All chromosomes duplicate…result in 2 identical parts = sister chromatids (X-shaped) * joined at centromere

5. When Cells Divide * sister chromatids separate..each goes to separate cell (daughter cell) * each daughter cell has complete set of chromosomes Overview of Cell Division * eukaryotic cells divide according to cell cycle cell cycle: sequence of events including time a cell divides until its daughter cell divide

7. Phases in the Cell Cycle 1) Interphase: most of cycle here - chromosomes duplicate - cell grows 2) Mitotic Phase: cell division phase Includes Mitosis & Cytokinesis * Mitosis unique to eukaryotes * Mitosis = continuous process but separated into defined stages

9. Stages of Mitosis 1) Prophase - chromatin fibers coil to form discrete chromosomes - sister chromatids - nuclear membrane breaks near end 2) Metaphase - sister chromatids line up along center of cell

12. Stages of Mitosis 3) Anaphase - sister chromatids separate & migrate to opposite ends of cell 4) Telophase - nuclear membrane reforms around chromosomes

14. Cytokinesis: division of cytoplasm - usually occurs along with telophase - daughter cells separate

15. -Certain drugs can stop cell cycle by preventing DNA synthesis, or inhibiting synthesis of necessary proteins Ex: cancer drugs target rapidly dividing cells – including hair follicles and digestive tracts

16. homologous chromosome: matched pair of chromosomes; same length, genes for same traits at same loci e.g., each chromosome has gene for hair color at same loci, but the gene may be for any color of hair … impt pt = gene results in some color of hair locus (loci = plural): specific location of a gene on a chromosome

19. homologous chromosomes have matching loci & One chromosome of each pair inherited from mother & father Human Example Somatic cells = 46 chromosomes 23 pairs of homologous chromosomes 22 pairs = autosome chromosomes (F & M) 1 pair = sex chromosomes; specific to the sex (M or F)

20. Sex Chromosomes Human females 1 pair (2 XX) Human male 1 pair (1X, 1Y) Are human male sex chromosomes homologous? diploid cells: cells with 2 homologous sets of chromosomes in nucleus total # chromosomes = diploid # = 2n human diploid # = 46 (2x23=46)

21. Humans = diploid animals because most of our cells = diploid (e.g., somatic cell) But, eggs & sperm are not diploid gametes: egg & sperm cells (sexual reproduction only) haploid cells: cells with 1 homologous set of chromosomes haploid # = n human haploid # = 23 Human gametes are haploid Fertilized egg = zygote = ????

22. Why is there so much variety among species? (e.g., diversity in humans) 1)Independent orientation of chromosomes -in Metaphase I --- way that tetrads line up is due to chance (random) -Results in different possible combinations of chromosomes in gametes -For humans = 8 million possible combos.!

24. 2) Random fertilization (1 egg & 1 sperm) What is probability that 1 of 8 million possible sperm fertilizes 1 of 8 million possible eggs???? Humans = (8 M) * (8 M) = 64 trillion possible combinations of chromosomes due to random fertilization!

25. 3) Crossing Over - can result in genetic recombination genetic recombination: producing gene combinations different from those carried by original chromosomes * During synapsis, tetrad formed – crossing over possible 1) homologous chromatids break at similar locations & chromatids join 2) h. chrom. separate at Anaphase I – crossing over 3) Meiosis II, sister chromatids separate

28. Mendelian Genetics genetics = science of heredity gene: specific region of genetic material (DNA) that provides provides the cell with a “map” Goal: determine patterns of inheritance Mendelian Genetics Gregor Mendel – 1860’s monk significant findings = offspring obtain discrete heritable factors (genes) from their parents

29. Mendelian Genetics Gregor Mendel – 1860’s monk -carefully chose organisms to study (garden pea), controlled pollinations, chose traits that were easy to observe, used statistical methods to analyze data -significant findings = offspring obtain discrete heritable factors (genes) from their parents

30. Terms self-fertilization: plant’s egg fertilized by it’s own pollen cross-fertilization: plant’s egg fertilized by another plant’s pollen (hybridization) P generation: parental generation F1 generation: filial generation; hybrid offspring of the P generation F2 generation: offspring produced by F 1 generation via self-fertilization

31. Mendel’s Principles 1) Principle of Segregation – pairs of genes segregate during gamete formation; fertilization pairs genes again monohybrid cross: cross of 2 individuals that differ in 1 trait allele: alternate form of a gene found at same loci of homologous chromosomes

32. 1) Principle of Segregation Ex: Flower color (P = purple, p = white) P = 1 Purple (PP) & 1 white (pp) F 1 = all Purple (Pp) F 2 = ¾ Purple (PP & Pp) ¼ white (pp) homozygous: identical pair of alleles heterozygous: 2 different alleles for a trait

34. phenotype: physical trait; appearance of organism; expressed as phenotypic ratio genotype: genetic makeup of organism; expressed as genotypic ratio In the flower color example….. What is the phenotypic ratio? What is the genotypic ratio? ** For monohybrid cross… phenotypic ratio is always 3:1 & genotypic ratio is always 1:2:1

36. 2) Principle of Independent Assortment each pair of alleles segregates independently during gamete formation dihybrid cross: cross of 2 individuals that differ in 2 traits

39. 2) Principle of Independent Assortment Example P generation: Round (RR) & Yellow (YY) seeds = RRYY Wrinkled (rr) & Green (yy) seeds = rryy Gametes = RY and ry F1 gen: All RrYy (Round & Yellow seeds) Gametes = RY, Ry, rY, ry Female Male RY ryRrYy

40. 2) Principle of Independent Assortment Example (continued) F2 gen:(Do Punnett Square Female Male RYryRyrY RY Ry rY ry

41. 2) Principle of Independent Assortment Example (continued) F2 gen:(Do Punnett Square Female Male RYryRyrY RY Ry rY ry RRYY

42. 2) Principle of Independent Assortment Example (continued) F2 gen:(Do Punnett Square Female Male RYry RRYy RyrY RY Ry rY ry RRYY RrYYRrYy

43. 2) Principle of Independent Assortment Example (continued) F2 gen:(Do Punnett Square Female Male RYry RRYy RyrY RY Ry rY ry RRYY RRYy RrYYRrYy RRyy RryyRrYy RrYY rryyrrYyRryyRrYy rrYyrrYYRrYy

45. Probabilities Probability (chance) of an event occurring ranges from 0 to 1 Probability = 0 = event will not occur Probability = 1 = event will occur always Tossing a Coin What is the probability of getting a “tails”? = 0.5 (1/2) What is the probability of getting a “heads”? = 0.5 (1/2) What is the probability of getting a “heads” or a “tails”? = P(heads) + P(tails) = 0.5 + 0.5 = 1.0

46. Tossing 2 Coins What is the probability of getting a “heads” on both coins? = P(heads) x P (heads) = (0.5)*(0.5) = 0.25

48. Flower Color Example F1 = Pp = 0.5 P & 0.5 p gametes F2 = Pp x Pp 1 P (female) x 1 P (male) = 0.5 * 0.5 = 0.25 PP 1 P (female) x 1 p (male) = 0.5 * 0.5 = 0.25 Pp 1 p (female x 1 P (male) = 0.5 * 0.5 = 0.25 Pp 1 p (female) x 1 p (male) = 0.5 * 0.5 = 0.25 pp What is the probability of getting a heterozygote? What is the probability of getting a homozygote?

49. Why are some flowers pink? Complete dominance = dominant & recessive alleles Incomplete dominance = F1 offspring have phenotype somewhere between that of the 2 parents = both alleles expressed Ex: Flower color (R = red, r = white) P = 1 Red (RR) & 1 white (rr) F 1 = all Reddish-White = Pink (Rr) F 2 = ¼ Red (RR), ¼ white (rr), ½ pink (Rr)

50. Incomplete Dominance

51. Pleiotropy vs. Polygenic Inheritance pleiotropy = 1 gene influence many traits e.g., sickle-cell anemia = homozygous recessive disease sickle-cell gene influences: - shape of RBC’s - health of heart, brain, spleen, kidneys polygenic inheritance = many genes influence 1 trait, e.g., skin color - many genes interact to give diverse skin color ranging very dark to very light

54. Chromosomal Basis

55. Review Problem / “Test-Like Question” Cross the following (assume complete dominance) AABbCC X AabbCc Where:A = no anemiaa = anemia B = brown eyesb = blue eyes C = climb treesc = don’t climb trees

56. 1)Find genotypes & phenotypes of F1 offspring & express in ratio format 2)Do a F1 X F1 cross using the AABbCC (one of the F1 offspring) & find the genotypes and phenotypes of the F2 offspring; express in ratio format 3)What is the probability of a F1 offspring having anemia, brown eyes, and tree-climbing abilities?