GENETICS

2. Heredity � the study of how genes/traits are passed along to offspring throughout generations.

4. �Looking at Your Traits� Number your paper 1-10 Beside each number, write the �Trait� we are looking at. Tell whether you are �dominant� or �recessive� for this trait. Lastly, write your �Genotype��which will be represented by given letters Ex. PTC-Dominant-TT or Tt Tongue Rolling-Dominant-RR or Rr

5. �Looking at Your Traits� 1. PTC is a chemical called phenylthio-carbamide and is harmless. It is used in medical genetics and as a diagnostic tool in medicine. The ability to taste the chemical is a dominant trait. People who cannot taste this chemical are recessive for the trait.

6. �Looking at Your Traits� 2. Tongue Rolling

7. �Looking at Your Traits� 3. Earlobes

8. �Looking at Your Traits� 4. Earbump

9. �Looking at Your Traits� 5. Widow�s Peak

10. �Looking at Your Traits� 6. Hitchhiker�s Thumb

11. �Looking at Your Traits� 7. Polydactyly

12. �Looking at Your Traits� 8. Syndactyly

13. �Looking at Your Traits� 9. Cleft Chin

14. �Looking at Your Traits� 10. Hair Whorl

15. I. Terms Trait � characteristic of an organism Gene � a heredity unit that codes for a trait. Allele � different gene forms Dominant � the gene that is expressed whenever it is present Recessive � the gene that is �hidden�. It is not expressed unless a homozygous condition exists for the gene.

16. I. Terms Homozygous � two identical (same) alleles for a given trait (TT). Heterozygous � two different (opposite) alleles for a given trait (Tt). Gamete � sexual reproductive cell. Fertilization � the fusion of two gametes. Phenotype � physical trait of an organism. Genotype � the genes present in the cell.

17. II. Gregor Mendel-�The Father of Genetics� A.*Mendel was the first to come up with rules regarding heredity-which formed the basis of genetics. Read Pages 162-169

19. B. Mendel�s Hypotheses For each inherited trait, an individual has two factors that control heredity (these �factors� are called genes) which are inherited from each parent.

20. B. Mendel�s Hypotheses There are alternative versions of genes�(each version is called an allele). Ex. Purple flowers or white flowers Brown eyes or blue eyes

21. B. Mendel�s Hypotheses When two different alleles occur together, one of them may be completely expressed, while the other may have no observable effect on the organism�s appearance. --Dominant or recessive Purple flowers are dominant to white flowers

22. B. Mendel�s Hypotheses 4. When gametes are formed, the alleles for each gene in an individual separate independently of one another. Thus, gametes carry only one allele for each inherited trait. When gametes unite during fertilization, each gamete contributes one allele.

23. C. Laws of Heredity Law of Segregation�the two alleles for a trait segregate (separate) during the formation of gametes (meiosis). Law of Independent Assortment�the alleles of different genes separate independently of one another during gamete formation. *Ex. The alleles for height separate independently of the alleles for flower color

24. III. Studying Heredity

25. A. Punnett Square Determine the traits used. Determine the dominant vs. recessive trait. Determine the letters for each trait. Express the cross and determine the gametes formed. Set up Punnett Square.

26. Punnett Square Place the two female gametes across the top Place the two male gametes down the side. Determine the offspring by filling in the squares.

27. Ex. Problem Trait-Eye Color Brown is dominant to blue B = Brown b = blue * Cross a homozygous brown eyed male with a blue eyed female.

28. Passing on of Traits IV. Sexual Reproduction-reproduction where two gametes unite.

29. Sexual Reproduction

30. A. MEIOSIS --A form of cell division that halves the number of chromosomes when forming specialized reproductive cells, such as gametes.

31. B. Chromosome Number in a Cell 1. Diploid number 2n�the number of chromosomes in a body cell of an organism. 2. Haploid number n�half of the diploid number. The diploid number for a human is 46 (humans have 46 chromosomes in each body cell) The haploid number for a human is ___ and is found only in the gamete cells (sperm/egg)

32. 2n n Homo sapiens (human) 46 23 Mus musculus (house mouse) 40 ___ Zea mays (corn or maize) 20 ___ Drosophila melanogaster (fruit fly) ___ 4 Xenopus laevis (South African clawed frog) ___ 18 Caenorhabditis elegans (microscopic roundworm) ___ 6 Saccharomyces cerevisiae (budding yeast) 32 ___ Canis familiaris (domestic dog) 78 ___ Arabidopsis thaliana (plant in the mustard family) 10 ___ Muntiacus muntjac (its Indian cousin) ___ 3 Myrmecia pilosula (an ant) ___ 1 Parascaris equorum var. univalens (parasitic roundworm) 2 ___ Cambarus clarkii (a crayfish) 200 ___ Equisetum arvense (field horsetail, a plant) 216 ___

35. GENDER & AUTOSOMES/SEX CHROMOSOMES Gender is determined by the combination of sex chromosomes inherited in the zygote. It is the sex chromosome within the sperm that is the determining factor (it provides either an X or Y). Also, it has been discovered that the Y chromosome carries a single gene, TDF (Testis Determining Factor) that determines maleness. (Girl= XX, Boy= XY) There are 23 pairs of chromosomes in humans. 22 pairs are autosomes(body) 1 pair is the sex chromosome(gender) The X chromosome is larger than the Y and it has extra genes on it that code for regular body traits.

36. Inheritance of Sickle-cell Anemia An amino acid substitution results in the sickle shape of the red blood cells. This causes the red blood cells to have low oxygen carrying capacity, and deprive tissues of oxygen. This can be fatal. The cell shape is elongated and curved, hence the �sickle� name instead of biconcave disk shape of normal cells. This disease is found almost exclusively in the African-American population and affects about 1 out of every 623 A.A. infants born in the U.S. The disease exists in Homozygous (ss) individuals. Heterozygous (Ss) individuals do not exhibit symptoms of the disease, but are considered carriers and have a resistance to malaria

37. Distinguish between sex-linked and autosomal disorders, Incomplete dominance, and Codominance Sex-linked diseases are inherited through one of the "sex chromosomes" -- the X or Y chromosomes. Autosomally inherited diseases are inherited through the non-sex chromosomes (autosomes), pairs 1 through 22. Dominant inheritance occurs when an abnormal gene from ONE parent is capable of causing disease even though the matching gene from the other parent is normal. The abnormal gene dominates the outcome of the gene pair. Recessive inheritance occurs when BOTH matching genes must be abnormal to produce disease. If only one gene in the pair is abnormal, the disease is not manifest or is only mildly manifest. However, the genetic predisposition to disease can be passed on to the children. Examples: (X-linked recessive),Color blindness�, �hemophilia A , Duchenne muscular dystrophy, (X-linked dominance): Retinitis pigmentosa , Rett syndrome , Vitamin D resistant rickets

38. X-linked diseases usually occur in males. Males have only one X chromosome, so a single recessive gene on that X chromosome will cause the disease. Although the Y chromosome is the other half of the XY gene pair in the male, the Y chromosome doesn't contain as many of the genes of the X chromosome and therefore doesn't protect the male. This is seen in diseases such as hemophilia and Duchenne muscular dystrophy. Females can get an x-linked recessive disorder, although it would be very rare. An abnormal gene on the X chromosome from each parent would be required, since a female has 2 X chromosomes. For an autosomal dominant disorder: If one parent has an abnormal gene and the other parent a normal gene, there is a 50% chance each child will inherit the abnormal gene, and therefore the dominant trait. Examples: Achondroplasia (dwarfism), Huntington disorder, neurofibromatosis, Polydactyly, Marfan syndrome

39. For an autosomal recessive disorder: When both parents are carriers of an autosomal recessive trait, there is a 25% chance of a child inheriting abnormal genes from both parents, and therefore of developing the disease. There is a 50% chance of each child inheriting one abnormal gene (being a carrier). Examples:� Galactosemia (the inability to metabolize lactose), cystic fibrosis, phenylketonuria, xeroderma pigmentosa, Tay-Sachs disease, Sickle cell disease INCOMPLETE DOMINANCE:� A heterozygous condition in which both alleles are partially expressed, often producing an intermediate phenotype. (sometimes called partial dominance) For example, when a snap dragon with red flowers is crossed with a snap dragon with white flowers, a snap dragon with pink flowers is produced�.OR�Like in Caucasians, the child of straight haired parents and a curly haired parent will have wavy hair� Straight and curly hair are homozygous dominant traits and wavy hair is heterozygous and is intermediate between straight and curly

40. CODOMINANCE:� In codominance, neither phenotype is completely dominant. Instead, the heterozygous individual expresses both phenotypes. A common example is the ABO blood group system. The gene for blood types has three alleles: A, B, and ii causes O type (ii) is recessive to both A and B. The A and B alleles are codominant with each other. When a person has both A and B, they have type AB blood.

41. Genetic Disorders

43. Pedigrees Pedigree help determine the inheritance and probability of human genetic disorders. Completely Affected individuals are shaded in, and Carriers are shaded only HALF of square or circle Square represents=male, circle represents= female Parental generation is at the top of pedigree, connected together with a horizontal line that signifies marriage/union Offspring are on the next lines, connected by a line that drops down

45. Karyotypes --A picture of the paired chromosomes, arranged in order from largest to smallest. Karyotypes can be obtained by blood samples or by amniocentisis. Amniocentesis detects or rules out Down's syndrome and other genetic malfunctions. If a pregnancy is complicated by a condition such as rh-incompatibility, your doctor can use amniocentesis to find out if your baby's lungs are developed enough to endure an early delivery.

47. NORMAL KARYOTYPES

50. Nondisjunction- the failure of chromosomes to separate properly during meiosis. Karyotypes can also detect other chromosomal abnormalities such as: Down�s Syndrome �an extra #21 autosome. Klinefelter�s Syndrome �an extra sex chromosome Turner�s Syndrome �a missing sex chromosome

51. DOWN�S SYNDROMEORTRISOMY 21

53. DOWN�S SYNDROME: Most common chromosome defects Occurs in 1 out of every 700 births Involves the autosomes� can affect either sex 47 total chromosomes, extra 21st chromosome (Trisomy 21) Produces mental impairments Distinctive facial characteristics, thick necks, short stocky bodies, thick tongue resulting in speech impediments, upper eyelids have extra folds of skin giving that heavy appearance, heart problems, decreased resistance to disease, and decreased life expectancy May develop Alzheimer�s as they age

54. KLINEFELTER�S SYNDROME

56. XXY sex chromosome condition produces Klinefelter�s syndrome 47 total chromosomes, including (2-X), and (1-Y) =XXY External Male genitalia appearance underdeveloped testes and do not produce sperm Partial breast development; or enlarged breasts usually sterile often mentally challenged; the more X�s present, the more physically and mentally defective these individuals are (XXXY, XXXXY) Occurs about 1 in every 1000 male births

57. TURNER�S SYNDROME

59. Turner's Syndrome 45 total chromosomes due to a single X sex chromosome rather than the usual 2 Rare chromosomal disorder of Females 1 IN EVERY 5000 FEMALE BIRTHS External Female genitalia, but breasts underdeveloped Lack functional ovaries, so no menstruation,and are sterile Short stature (less than 5 ft.) and the lack of sexual development at puberty� Other physical features may include a webbed neck/shoulders, heart defects, kidney abnormalities, and/or various other malformations. Usually Normal intelligence Normally, females have two X chromosomes. � Karyotype link �

60. Identify advances in genetic technology and the ethical responsibilities that follow With the increasing strides in genetic engineering comes more responsibility and ethical concerns involving the safety with this type of advancement in altering both plant and animal genetic make-up. There are many benefits and risks involved In the twentienth century, advances in plant breeding started using the principles of genetics to select plants. Today, genetic engineers can change/add favorable characteristics to a plant by manipulating the plant�s genes� such as: developing bigger/tastier crops, being able to tolerate drought and different climates, heat/cold, adapting to different soils, resistant to insects, and improving the nutritional values of the crop plants, etc� Soon after the advances with crop plants, farmers started using genetic engineering to improve and modify the farm animals. Altering growth hormone amounts in the animals diet increased many things such as weight, milk production, etc� Another way gene technology is used with animals is adding in human genes to farm animals in order to get human proteins produced in their milk. The proteins are then sold for pharmaceutical purposes. These animals are called transgenic animals because they have foreign DNA in their cells.

61. Cloning is also a very controversial topic in this field. Scientists turn to cloning as a way to create herds of identical animals that can make medically useful proteins. They have successfully cloned animals since 1996, but most have not survived due to many different technical complications�because of these technical and ethical problems, efforts to clone humans are illegal in most countries. Launch of Human Genome Project (1988) First mammal cloned (sheep, in Scotland, by Ian Wilmut) (1996) Legislation to ban cloning dies in US Senate after heavy lobbying by the biotech industry. Senators are told that human cloning wouldn't be technically possible for "at least 10 years (1998) A child conceived in part to provide therapeutic tissues for an earlier-born sibling is born. Techniques of preimplantation genetic diagnosis are used to ensure that the child does not itself carry the disease. The press erroneously hails the child as the world's first "designer baby (2000)

63. US congressional hearings begin on legislation banning human cloning(2001) Scientists at Texas A & M University announce that they cloned a cat in December, the first cloning of a house pet(2002) The first complete sequence, accurate to 99.999%, of the genetic code of a single human is announced (2003) A horse is cloned(2003) Korean researchers announce that they have succeeded in cloning human embryos and extracting stem cells from them. A mouse is born with two female parents and no male parent (2004) Use of preimplantation genetic diagnosis (PGD) to provide stem cells for children suffering from non-genetic diseases.(2004)