Number of Chromosomes

1. Number of Chromosomes • Organisms have 2 different types of cells • Body (somatic) cells: skin, liver, brain • Sex cells (gametes): sperm and egg • Because sperm and egg need to meet and combine their chromosomes to form a new individual, they have ½ the number of chromosomes as body cells • http://www.twigcarolina.com/films/glossary/zygote-4254/

2. Structure of DNA • DNA is made up of nucleotides. Each nucleotide of DNA consists of: • A sugar “deoxyribose” • A phosphate • A nitrogenous base: • Adenine Thymine • Cytosine Guanine http://www.twigcarolina.com/learning-materials/cells-and-dna-dna-89/ PLEASE SKETCH THIS IN YOUR NOTES

3. When nucleotides are bonded, they compose a DNA molecule PLEASE SKETCH THIS IN YOUR NOTES • Double-helix/spiral ladder • Sugar-phosphate “backbone” • Bases are rungs of ladder • Long sequences of bases make up gene

4. DNA in the Cell nucleus • DNA is located in the ________ of a cell. • While in the nucleus it is in the form of chromosomes . • Chromosomes contain the genes • Different species have different amounts of chromosomes. Humans = 46 http://www.twigcarolina.com/films/glossary/chromatin-4283/ http://www.twigcarolina.com/films/glossary/chromosome-4284/

6. Cells are formed by Mitosis and Meiosis • Mitosis is the division of a cell into body cells. http://www.twigcarolina.com/films/glossary/mitosis-4313/ http://www.twigcarolina.com/films/glossary/mitosis-4313/ http://www.twigcarolina.com/films/cell-division-mitosis-3197/ http://www.lpscience.fatcow.com/jwanamaker/animations/mitosis.html • Meiosis is the division of a cell into sex cells. http://www.twigcarolina.com/films/cell-division-meiosis-3349/ http://www.twigcarolina.com/learning-materials/cells-and-dna-the-cell-86/ http://www.lpscience.fatcow.com/jwanamaker/animations/meiosis.html http://cellsalive.com/meiosis.htm

7. Please Sketch

8. Mitosis/Meiosis Animation http://www.pbs.org/wgbh/nova/miracle/divi_flash.html

9. How does mitosis make more cells with the same DNA? • http://www.twigcarolina.com/films/glossary/dna-replication-4298/ • http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

10. n=23 human sex cell sperm n=23 2n=46 haploid (n) n=23 diploid (2n) n=23 Spermatogenesis Crossing-over occurs at this stage 4 genetically different gametes are produced

14. Karyotype Performance Assessment Preparation Homework: Briefly (total of 30 min) research Karyotyping, Amniocentesis, Chorionic Villi Sampling and the following conditions: • Down Syndrome – Trisomy 21 • Turner Syndrome – Monosomy (X0) • “Supermale” – Trisomy XXY • PatauSyndrome – Trisomy 13 • Edwards’ Syndrome – Trisomy 18 The goal is to become familiar with these terms so that you are able to delve deeper into understanding them throughout the course of this assignment.

15. CHROMOSOME NUMBERS sex cells/haploid (N) Body cells/diploid (2n) • 23 • 12 • 4 • 20 • 10 • 22 • 46 • 24 • 8 • 40 • 20 • 44

17. eye color locus eye color locus hair color locus hair color locus From Dad From Mom Homologous Chromosomes PLEASE SKETCH THIS IN YOUR NOTES

18. Tetrad homologous pairs Crossing Over = Variationhttp://www.twigcarolina.com/films/glossary/recombination-4747/ Tetrad, homol. pairs together This causes genetic variation PLEASE SKETCH THIS IN YOUR NOTES

19. Cell Reproduction Videos • http://education-portal.com/academy/lesson/the-genome.html#lesson • http://www.watchknowlearn.org/Video.aspx?VideoID=39312 • http://www.watchknowlearn.org/Video.aspx?VideoID=31175&CategoryID=7580

20. Chromosomes are counted on karyotypes Normal Human Karyotype: • 46 chromosomes • 23 pairs • 44 autosomes • 22 pairs • 2 sex chromosomes • 1 pair • XX = female • XY = male

21. Nondisjunction causes errors in chromosome numbers • Nondisjunction is when the chromosomes don’t split evenly in meiosis, resulting in too many or too few chromosomes in the sperm or egg. • Examples of diseases/conditions caused by non-disjuction: • Down’s Syndrome = 47 • Turner’s Syndrome = 45 • Klinefelter’s Syndrome = 47 http://www.biostudio.com/d_%20Meiotic%20Nondisjunction%20Meiosis%20I.htm

22. Down’s Syndrome Karyotype

23. Practice w/Karyotypes

24. PHENOTYPE – the physical characteristics of an organism (an adjective) • Brown, black, blue, pink, tall, short, round, wrinkled • GENOTYPE – the genes of an organism as represented by letters: • Homozygous dominant (BB) • Heterozygous (Bb) • Homozygous recessive (bb)

25. Homozygous – an individual who has the same alleles for a trait. Ex. 2 genes for cystic fibrosis • Heterozygous – an individual who has different alleles for a trait. Ex. One gene for cystic fibrosis, one for normal

26. If an organism is heterozygous, it is showing the dominant phenotype. Cross a heterozygous gray squirrel with a black squirrel:

27. Genetics Terminology • Genes – segment of DNA that codes for a trait • Alleles – different versions of a gene: • Allele for brown eyes, allele for blue eyes • Both genes code for hair color, but have different versions • Letters are used to indicate alleles. Ex. B, b

28. Dominant – The allele that is expressed • Recessive – The allele that is not expressed when paired with a dominant. Only expressed when paired with another recessive gene Ex) Heterozygous brown mouse (Bb) 1. how do you know brown is the dominant phenotype? 2. How do you know to use the letter “B” or “b”

29. Generations • Parent generation = P • Offspring of P generation = F1 • Offspring of F1 generation = F2 1. Cross a homozygous dominant purple flower with a homozygous recessive white flower. Give the F1 genotype and phenotype percents. Purple = PP, white = pp 2. Give the F2 geno/phenopercents

30. Practice Crosses • Cross Bb x Bb (black and white) • Give the F2 of BB x bb (black and white) • Cross a heterozygous black mouse with a white mouse. Give the F1 • Cross a homozygous dominant black mouse with a white mouse. Give the F2. • Cross two carriers (Nn) for cystic fibrosis • Cross a normal/unaffected (NN) with an affected (nn) for cystic fibrosis. • Cross a normal/unaffected with a carrier for tay-sachs *When finished with correct answers checked by a teacher, pair up with someone who needs help.

31. Phenotype: _______ % ___________ _______ % ___________ Genotype: ________% Hom. Dom. ________% Het. ________% Hom. Rec.

32. Sex-linked inheritance • Males and females inherit some diseases with different frequency. • This is because the Y-chromosomes have fewer genes • Examples: hemophilia and color-blindness • Punnett squares that separate the chances of males and females getting diseases How males and females inherit: XN Y or Xn Y XNXN or XNXn or XnXn

33. Oogenesis – eggs can only have X as 23rd b/c females are XX • Spermatogenesis – sperm can make X or Y sperm b/c men are XY

34. SOME GENES ARE ONLY ON THE X AND THEREFORE INHERTED ONLY FROM MOM If females inherit one “bad” recessive gene from their mom (X c-some), they will typically inherit a “good” dominant gene from the dad. Males don’t have that option b/c they only get 1 gene. So if that 1 gene they receive is “bad,” it can’t be negated by a “good” gene from the other parent. Ex) if a mom is color-blind, her sons will all be colorblind b/c the dad can’t give a color-vision gene.

35. How to set-up the “stats” for sex-linked crosses Female: Phenotype: Genotype: _______% unaffected _______% normal _______% affected _______% carrier _______% diseased Male: Phenotype: Genotype: _______% unaffected _______% normal _______% affected _______% diseased

36. Cross a colorblind woman with a normal-visioned man

37. Cross a female carrier of hemophilia with a normal male Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

38. Cross a female hemophiliac with a normal male Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

39. Cross a carrier with a hemophiliac Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

40. #5 Cross a normal female with a colorblind man Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

41. 6. Cross a colorblind woman with a normal-visioned man Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

42. 7. Cross a colorblind carrier with a normal visioned person Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

43. 8. Cross a hemophilia carrier with an unaffected person. Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

44. 9. An affected female with a non-hemophiliac male. Female: Phenotype: _______% unaffected _______% affected Genotype: _______% normal _______% carrier _______% diseased Male: Phenotype: _______% unaffected _______% affected Genotype _______% normal _______% diseased

45. Suppose that a man with hemophilia marries a woman whose father had hemophilia. show the genotypes of the man and the woman. What are the chances that their daughters will have hemophilia? What are the chances that their sons will have hemophilia?

49. Pedigree Charts • Pedigree charts follow a genetic mutation/disease through several generations of a family. • You can determine what chance offspring has of having a disease based on family history and Punnett Square. • The main diseases that are tracked this way are: • Tay-sachs, Cystic Fibrosis and Sickle-cell (autosomal recessive – NN, Nn, nn) • Huntingtons (autosomal dominant – HH, Hh, hh) • Colorblindness and Hemophilia (sex-linked/X-linked)

50. Basic Symbols