1. discovered how genes are inherited by using peas. 2. cross pollinated peas

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3 I. Mendel & the Idea of Alleles A. Gregor Mendel 1. discovered how genes are inherited by using peas 2. cross pollinated peas

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6 3. concentrated on 7 traits that did not fit blending theory 4. blending theory mixing of parents genes. Average of both. genes could not be passed down separately

7 P generation (parent): Took pollen from 1 plant & transferred it to another (true breeding) F 1 generation: offspring of the parent (p generation) hybrids a. hybrids offspring of 2 different true breeding organisms b. Allowed to self fertilize F 2 generation: offspring of F1 generation when crossed with each other.

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10 P generation True breeding F1 generation (hybrid) F2 generation Purple flowers X white flowers (cross fertilized) All Purple Flowers (self fertilize) ¾ purple flowers & ¼ white flowers 7. Monohybrid cross crossing only one kind of trait Ex:) seed shape

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12 B. Mendel s Findings 1. demonstrated both parents passed on genetic factors that remain separate (not blended) 2. Genes replace Mendel s idea of factors 3. Gene is NOW defined segment of DNA whose sequence of nucleotides code for a specific functional product. a. Products = ribosomal, transfer RNA & proteins.

13 4. Alleles 1, 2 or more forms of a gene a. Each allele of a particular gene has a diff. base sequence. b. All org. have genes that have several diff. alleles ex:) Gene for hairline: widow s peak, no widow s peak

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16 II. Mendelian Patterns of Inheritance A. Probability chance that a certain event will occur 1. Probability = # events of choice # events possible 2. Ex:) probability of drawing a spade out of a deck of card

17 a. 13 spades in deck 52 cards in deck =.25 or 25% b. 1 ace of diamonds 52 card in deck =.02 or 2% c. 40 red jelly beans, 32 blue, 12 green, 4 orange. Prob. Of grabbing a green? Red? Blue? Orange?

18 3. Flipping a Coin a. Chance of getting heads or tails? 2 sides = 50% chance each b. Tossed coin 5 times and got all heads. Chance of getting tails? still 50%

19 c. Prob. of getting all heads when tossing 4 coins simultaneously? multiply the changes of it occurring separately ½ x ½ x ½ x ½ = 1/16

20 d. 2 coins toss: Probability of: H/H, H/T or T/H, T/T toss 2 coins 100 times more likely land on H/T ½ X ½ = ¼, ½ X ½ = ¼ or ½ X ½ = ¼, ½ X ½ = ¼ ¼ (100) ¼ (100) or ¼ (100), ¼ (100) 25 H/H, 50 H/T or T/H, 25 T/T,

21 III. Genes and Chromosomes A. Eukaryotic Chromosomes 1. long molecules of DNA wrapped around proteins 2. Only part of this DNA codes for a protein (1.5%)

22 3. noncoding (junk) DNA is sometimes transcribed, but NOT translated a. Some = short seq. of bases repeated 1000 s of times b. importance for most is unknown c. some involved with gene expression & chrom. stability

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24 B. Sorting Chromosomes 1. staining chrom. creates banding patterns that are specific 2. sorted by size, shape, centromere location, banding patterns & painting

25 3. Karyotype sort chromosomes according to size, type and #. a. humans have 23 chromosome pairs B nd autosomal chromosomes b. 1 pair #23 sex chromosomes female: XX Male: XY (½ sperm X, ½ Y)

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31 The chromosomes were isolated from a cell taken from a patient with Werner Syndrome, a premature aging disease that is caused by the loss of the WRN gene. Painting each chromosome pair in a different color reveals the breakage and fusion of chromosomes (see chromosomes 6 and 10), which causes genomic instability and could explain the high incidence of cancer among individuals with Werner syndrome.

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33 The chromosomal fingerprint, or karyotype, of a normal human cell (left), includes 46 paired chromosomes. The distinctive karyotype of an aneuploid breast cancer cell, however, (right) includes duplicates of entire chromosomes, missing chromosomes, and chromosome stubs. The chromosome pattern also includes marker chromosomes seen in all the cancer's cells, indicating changes that originated in the cell that gave rise to the cancer. Numbers under each marker chromosome indicate the chromosome from which the fragment came; while plus and minus signs identify those that are larger or smaller than usual.

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37 IV. Human Genome Project (HGP) A. Objective 1. Determine sequence of 3 bill. bp of DNA 2. Started in 1988: projected: 15 yrs to do and cost 3 bill. completed 2003 and cost little more than 1 bill! 3. Mapped where on our chrom. 35,000 genes were located

38 4. Also provided complete DNA seq. of EACH chrom. 5. have now seq. over 100 sp. of bacteria and dozens of eukaryotes

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40 B. Inheritance of Alleles 1. Dominant trait that is visible or expressed 2. recessive trait that is MASKED by a dominant but still present 3. homozygous 2 identical alleles for a trait Ex:) RR rr

41 Dominant Recessive

42 4. heterozygous 2 different alleles for a trait Ex:) R r 5. genotype alleles that are the genetic make up 6. phenotype observable trait of the genetic make up

43 Ex:) Rr = round Phenotype Genotype BB = brown hair 7. Principle of Segregation In meiosis, chromosome pairs separate & go to 2 different gametes.

44 C. Punnett Squares diagram that shows all possible outcomes of a genetic cross Examples: R r Rr Rr r R Rr Rr RR = 0% round rr = 0% wrinkled Rr= 100% round

45 Problem: Cross a homozygous dominant puppy with a homozygous recessive puppy B = brown b = blue If they have puppies, what % of puppies will be: Brown Blue Homozygous Heterozygous

46 R r R RR Rr RR = 25% round rr = 25% wrinkled r Rr rr Rr= 50% round

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49 D. Dihybrid Cross crossing 2 characteristics of an organism 1. Principle of Independent Assortment genes for 2 different traits DO NOT influence each others inheritance.

50 P Generation Gametes 2. Dihybrid cross assort in a 9:3:3:1 ratio RRYY RY X rryy ry F1 Generation F2 Generation RrYy (all round/yellow) 4 Phenotypes 9: 3: 3: 1

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52 V. Many Variations of Inheritance A. Incomplete Dominance heterozygotes have phenotype intermediate between 2 homozygotes 1. Ex:) black chicken X white (C B C B ) (C W C W ) B. Multiple Alleles blue chicken (C B C W ) several known alleles for 1 gene

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56 What is in blood? White blood cells Platelets Plasma Red Blood Cells

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58 1. 4 blood types : A B AB O TYPE A I A I A ALLELE or I A i B I B I B or I B i AB O I A I B - codominant ii 2. Codominance a heterozygote that expresses BOTH traits

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62 Who Can Receive Whose Red Blood Cells: O - can only use O - O + can use O + or O - A - can use A - or O - A + can use A +, A -, O + or O - B - can use B - or O - B + can use B +, B -, O + or O - AB - can use AB -, A -, B - or O - AB + can use All Blood Types

63 Rh Factor If your blood does contain the Rh protein, your blood is said to be Rh positive (Rh+) If your blood does NOT contain the Rh protein, your blood is said to be Rh negative (Rh-)

64 Agglutination

65 3. Type AB = rarest. can accept any blood type 4. Type O = most common blood type Only can accept O blood Give to any blood type 5. antibodies defensive proteins found in blood a. Causes clumping if 2 non compatible blood types mix

66 C. Linked Genes genes on same chromosome are said to be linked 1. Often inherited together 2. farther apart 2 genes are on chrom. more likely a break will occur between them may assort independently

67 D. X linked traits (Sex linked) 1. gene for a trait carried only on the female X chromosome 2. NO genes carried on Y chromosome except the male reproductive genes traits found Ex:) hemophilia, color blindness, muscular dystrophy, baldness

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69 The Y chromosome likely contains between 70 and 400 genes. Because only males have the Y chromosome, many of the genes on this chromosome are involved in male sexual determination and development.

70 4. Barr Bodies a. In females: 1 X chromosome becomes inactivated in each body cell The Barr, or sex chromatin, body is an inactive X chromosome. It appears as a dense, dark-staining spot of the nucleus of each somatic cell in the human female.

71 Calico Cat Is there a human calico cat? Lionization in a Calico cat. The random pattern of orange and black fur is due to the random inactivation of the X chromosomes 2001 Lee Bardwell

72 Lionization in a human female. The pink areas represent patches of skin that have no sweat glands, a condition known as dermal displasia. The gene controlling dermal displasia is located on the X chromosome

73 Lyon hypothesis 1. One X chromosome in each cell becomes inactivated early in development a. The one that is deactivated is random b. All cells derived from cell with deactivated chromosome will have that chromosome deactivated c. This results in genetic mosaics 1. Examples a. Calico cats b. Sweat gland distribution in females heterozygous for extodermal dysplasia

74 COLORBLINDNESS C= non colorblind c= colorblind Cross: X C Y = non colorblind X C X c = non colorblind (carrier) X C X c X C X C X C X C X c Y X C Y X c Y

75 Results: X C X C /X C X c = 100% non colorblind F X C Y= 50% non colorblind M X c Y= 50% colorblind Male

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77 E. Nondisjunction homologous chromosomes fails to separate during meiosis 1. Down Syndrome a. Trisomy 21 3 chromosomes on 21 st pair. (2= normal) b. 47 chromosomes c. Limited mental ability, heart defects, short stature etc. d. 95% reach adulthood, 80% live into early 50

78 2. Too few or too many chromosomes 3. Extra autosomal chromosomes= death (miscarriage)

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83 F. Sex Chromosome Error 1. offspring can survive 2. Turner Syndrome X NO Y a. Female 45 chromosomes b. Short, underdeveloped, sterile 3. Trisomy X- XXX a. Female- 47 chromosomes b. Physically normal c. slightly below average intelligence

84 Turner's Syndrome characteristics. Webbing of the neck, barrel chest, appendence of secondary sex characteristics in an eighteen-year-old female

85 Turner's Syndrome (XO)

86 Turner Syndrome = 45, X (female, sterile) 0.5% female births

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88 4. Klinefelter Syndrome = XXY a. Male- 47 Chromosomes b. Tall, not fully sexually developed 5. XYY or XYYY a. Male Taller than average b. Slightly lower intelligence c. study done 1970 s- super male aggressive/violent- never been confirmed

89 47, XYY males: Individuals are somewhat taller than average and often have below normal intelligence. At one time (~1970s), it was thought that these men were likely to be criminally aggressive, but this hypothesis has been disproven over time.

90 Characteristics of Klinefelter's Syndrome

91 Klinefelter Syndrome = 47, XXY (male, sterile) 0.1% male births

92 Chromosome Abnormalities and Pregnancy Loss About 1/3 of human pregnancies are lost spontaneously after implantation Chromosome abnormalities are the leading known cause of pregnancy loss A minimum 10-15% of conceptions have a chromosome abnormality At least 95% of these conceptions spontaneously abort 1999 Lee Bardwell

93 Fragile X: the most common form of mental retardation. The X chromosome of some people is unusually fragile at one tip - seen "hanging by a thread" under a microscope. Most people have 29 "repeats" at this end of their X-chromosome, those with Fragile X have over 700 repeats due to duplications. Affects 1:1500 males, 1:2500 females.

94 Pictures of Developmental Abnormalities Sex Chromosome Error Questions Human Genetics ppt. Karyotype Lab

95 Hermaphrodites - Have both ovaries and testes - External genitalia are ambiguous - Generally, true hermaphrodites are sterile but not always (at The American Society of Human Genetic meeting in Vancouver, B.C) a case was reported in which a 25 yr old hermaphrodite delivered a stillborn after 30 weeks of gestation - True hermaphrodites are genetic mosaics some cells are XX, while others are XY

96 G. Multifactorial (Polygenic Inheritance) 1. when 2 or more genes affect a single characteristic & environment 2. Ex:) height, skin color, weight, intelligence, hair, eye color 3. skin pigment melanin: controlled by 4 different genes & light exposure

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101 B. Pedigrees family tree that records & traces traits C.

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106 Achondroplasia is the most common of the many types of short-limbed dwarfism. Achondroplasia is characterised by abnormal bone growth that results in short stature with disproportionately short arms and legs, a large head, and characteristic facial features. Intelligence and life span are usually normal, although an increased risk is present for death in infancy from compression of the spinal cord and/or upper airway obstruction. Achondroplasia is the most common form of inherited disproportionate short stature. It occurs in one in 15,000 to one in 40,000 live births.