Dragonfly Chapter 14

1. Dragonfly Chapter 14 The Human Genome

2. Section 14-1: Human Heredity Key Concepts: How is sex determined? How do small changes in DNA Cause genetic disorders? • Human Chromosomes • A. Karyotype: A picture of chromosomes taken during mitosis and cut out and arranged into homologous pairs.

3. Diploid Cell: ________ of homologous chromosomes • Human diploid cell has ____ chromosomes arranged in ____ pairs • The 46 chromosomes contain Two sets 46 23 • 6 billion nucleotide pairs Mendelian genetics requires that organisms of gene from each parent inherit a single copy • In humans, _______________ (reproductive cells of egg and sperm) contain a single copy of each gene (one set of genetic information). the gametes

4. testes Gametes are formed in the __________ (sperm) and __________(egg) by meiosis. Each gamete contains 23 chromosomes (one set) or __________________ (N) of chromosomes. ________________ requires the egg and the sperm to join and produce a ______________ (fertilized egg) that contains 46 chromosomes (two sets) or _____________________ (2N). ovaries haploid number Fertilization zygote diploid number

5. Humans have 46 total chromosomes • 44 _____________ follow regular Mendelian genetics • 2 _________________ (X and Y) are sex-linked autosomes sex chromosomes • Pedigree Chart: A pedigree chart shows the _________________ within a family and can be useful to help with __________________________ within families. It is another __________________ • _________ of a particular cross and the genotype of the family members. relationship genetic inheritance problems way to predict the outcome

6. Figure 14-3 A Pedigree Pedigree Section 14-1 A circle represents a female. A square represents a male. A vertical line and a bracket connect the parents to their children. A horizontal line connecting a male and female represents a marriage. A half-shaded circle or square indicates that a person is a carrier of the trait. A circle or square that is not shaded indicates that a person neither expresses the trait nor is a carrier of the trait. A completely shaded circle or square indicates that a person expresses the trait.

7. Human Traits • Phenotypes are determined by genotype as well as ________________________________. • ________________________________ on gene expression are not inherited, but genes are. environmentally influenced Environmental influences

8. III. Human Genes The __________________: Complete set of genetic information Composed of about 30,000 genes human genome • Blood Group Genes • Human Blood comes in a variety of genetically determined blood groups • There are many different types of blood groups but the ones associated with the ABO blood group and the Rh blood groups are best known. • .

9. Rh blood groups is controlled by single gene with ________________. It is another antigen in blood, first discovered in Rhesus monkeys. The arrangement of the alleles determines only _______ possible types _____________ (+) contains the antigen, or ___________ (-) doesn’t contain the antigen. Positive is ______________ over negative. Rh-positive is identified with two genotypes: Rh+/Rh+ or Rh+/Rh- Rh-negative is identified with one genotype: Rh-/Rh- Two alleles two positive negative dominant

10. ABO Blood Groups: Discovered in 1900 by Karl Landsteiner. He realized that all blood is classified into four types: ____, ____, ____, and _____ due to the presence of or absence of specific __________ in the blood. • Alleles IA and IB are __________________ and io is ________________ to both IA and IB A O B AB antigens codominant recessive • Antigens are ______________________ used by the immune system. When an unrecognized antigen is present an immune response takes place and the cells ____________________________. chemical markers _ clump or agglutinate

11. Figure 14-4 Blood Groups Blood Type and Antigen Interactions Section 14-1 Safe Transfusions Antigen on Red Blood Cell Phenotype (Blood Type Genotype From To Go to Section:

12. only if both alleles are recessive B. Recessive Alleles: Trait controlled by a recessive allele. This results in the disorder being present ___________________________. • Examples include: PKU (Phenylketonuria), Tay Sachs disease and Cystic Fibrosis, Albinism, and Galactosemia (See chart on page 345)

13. only one allele is present C. Dominant Alleles: Traits controlled by a dominant allele. This results in the disorder being present when __________________________. • Examples include: Achondroplasia (dwarfism), Hypercholesterolemia, and Huntington’s Disease

14. Codominant alleles Recessive alleles Dominant alleles Tay-Sachs disease Huntington’s disease Sickle cell disease Galactosemia Albinism Cystic fibrosis Hypercholes- terolemia Phenylketonuria Achondroplasia Autosomal Disorders Section 14-1 Autosomol Disorders caused by include include include

15. Huntington Disease: • It is controlled by a _________________________. The gene is located on Chromosome #4. single dominant allele • Genetic degenerative disease that shows no symptoms until a person is in their ____________________. It progresses with gradual degeneration of their nervous system leading to loss of muscle control and mental function until death occurs. thirties or forties

16. Question? Would you want to know now if you could potentially get Huntington’s disease when you are older? Would you want to know if you could pass the gene on to your offspring before you have children? A. Codominant Alleles: controlled by _______________________________________. Sickle Cell Anemia is such a disorder. (This will be discussed in detail later) two alleles that share dominance

17. genetics and phenotype IV. From Gene to Molecule The link between ______________________ is not easily determined but for several diseases we have been able to make the connection. For both _____________ and ________________ a small change in the DNA of a _____________ affects the ______________________, causing a serious genetic disorder. Cystic fibrosis Sickle cell disease single gene structure of a protein

18. A.Cystic Fibrosis: (See figure 14-8 p. 347) Cystic Fibrosis a.k.a. “CF” is a common genetic disease. It is most common in people of Northern European decent. It is a _______________________ of a gene found on the # 7 chromosome and affects the______________________________ Recessive disease digestive and respiratory systems

19. deletion of 3 bases abnormal It is caused by the____________________ in the middle of a sequence for a protein and causes the protein to be ______________ and doesn’t allow Chloride ions to transport across the membrane, as they should. This causes the cells in a person’s airways to be unable to transport chloride ions and become __________________. clogged with mucus

20. Figure 14-8 The Cause of Cystic Fibrosis Section 14-1 Chromosome # 7 CFTR gene The most common allele that causes cystic fibrosis is missing 3 DNA bases. As a result, the amino acid phenylalanine is missing from the CFTR protein. Normal CFTR is a chloride ion channel in cell membranes. Abnormal CFTR cannot be transported to the cell membrane. The cells in the person’s airways are unable to transport chloride ions. As a result, the airways become clogged with a thick mucus.

21. like a sickle B. Sickle Cell Anemia The patient’s blood cells were found to be irregularly shaped, ____________________, and this is how the disease got its name. In normal red blood cells the ____________________ carries ___________ and distributes it around the body. In sickle cell disease, the red blood cells are sickle–shaped, causing the blood hemoglobin to no longer carry oxygen as well and _____________________ oxygen hemoglobin molecule disrupts the normal functioning of the bodies cells, tissues and organs

22. This person is deprived of oxygen and the result is physical weakness, and damage to the brain, heart, spleen. It may be fatal. The cause: A _________________ in the DNA that codes for Hemoglobin polypeptides is changed. This substitutes Valine for glutamic acid. This change makes the hemoglobin less soluble in blood. This will cause the hemoglobin to come out of the blood and _______________. This crystallization causes the ________________ of the blood cells and the medical consequences. single base crystallize sickle shape

23. The genetics: The allele for sickle cell (HS) is ___________ with the allele for normal hemoglobin (HA). codominant • Heterozygotes (HS HA) are said to be ____ ____ __________ and have some effects of the disorder because they have both normal and sickle cell blood hemoglobin. Sickle cell carriers

24. DNA normal hemoglobin CAC GTG GAC TGA GGA CTC CTC Messenger RNA sequence GUG CAC CUG ACU CCU GAG GAG Normal hemoglobin amino acid sequence Val – His – Leu – Thr – Pro – Glu – Glu… 1 2 3 4 5 6 7 …146 DNA Sickle Cell Anemia CAC GTG GAC TGA GGA CAC CTC Messenger RNA sequence GUG CAC CUG ACU CCU GAG Val – His – Leu – Thr – Pro – – Glu… 1 2 3 4 5 6 7 …146

25. The distribution: Sickle Cell anemia is most prevalent in people of __________________. • 10% of African Americans and 40% of populations in Africa and Asia carry the gene for Sickle cell anemia. • Why? The carriers for the disease have a ___________________, a dangerous disease caused by a blood parasite found in tropical areas of the world. African descent resistance to Malaria

26. Sickle Cell Anemia is a __________ that has provided an ____________ in Malaria prone areas and in these areas it is _______________________ and therefore Sickle Cell Anemia persists. mutation advantage favored by natural selection HS HA HS HS HS HA HS HA HS HA HA HA

27. Section 14-2: Human Chromosomes Key concepts: Why are sex-linked disorders more common in males than in females? What is nondisjunction, and what problems does it cause?

28. 6 billion base pairs Small part I. Human Genes and Chromosomes Human diploid cell contains ______________________ of DNA. All neatly packed into the 46 chromosomes. __________________ of the DNA actually functions as genes. Genes are located on the chromosomes and each gene occupies a ______________________ on a chromosome. Genes may exist in ____________________ (alleles) Each chromosome contains ______ of the alleles for each of its genes Chromosome #21 and 22 are the ____________ of the human autosomes. These were the first two chromosomes whose sequences had been determined. specific place several forms one smallest

29. Leukemia and Amyotrophic Lateral Sclerosis (ALS) Both also contain genes for some genetic disorders like ________________________ ___________________________ We also discovered that there are many _________________________ segments of DNA Human chromosomes also have ________________ that can cross over just as we saw in the fruit fly. non-coding, repeating Linked genes

30. Sex Chromosomes differ same II. Sex-linked Genes 1. _______________________ are the ones that __________ in males and females 2. Chromosomes that are the ________ in male and females = _______________ 3. In humans: females = ____ and Males = ____ 4. The Y chromosome is smaller than the X autosomes XY XX

31. gametes Male 50% A. Sex Determination 1. Female _________ carry an X chromosome 2. _________ gametes can carry either an X or Y (meiosis segregates the chromosomes; _______ of the sperm carry X and ______ of the sperm carry Y) 3. In humans, _____________________________ of an offspring Female: XX male: XY 50% males determine the sex X Y X XX XY X XX XY

32. differing In some animals such as birds, butterflies, and some fish, the female determines the sex because she has the __________ chromosomes. Sex-linked Genes 1. In addition to determining the sex of an individual, the sex chromosomes carry genes that ____________________ affect other traits.

33. Sex-linked Genetic Disorders • May be on the X or Y chromosome, but •  Most often expressed in ____________because they only have one X chromosome and thus all the alleles are expressed even if they are recessive. usually on the X because the Y has very few genes. males • Colorblindness is a recessive disorder in which people can’t distinguish between certain colors. ____________________ colorblindness is most common. • XC and Xc are ________________ for normal and colorblind vision. Red-green the alleles

34. XC XC and XC Xc are • XC Xc is a _______________________ and can pass the gene on to her sons. • Xc Xc is a • XC Y is a • Xc Y is a both normal vision females. carrier for colorblindness colorblind female. normal male and colorblind male. http://www.toledo-bend.com/colorblind/Ishihara.html

35. Figure 14-13 Colorblindness Colorblindness Section 14-2 Father (normal vision) Normal vision Colorblind Male Female Daughter (normal vision) Son (normal vision) Mother (carrier) Daughter (carrier) Son (colorblind) Go to Section:

36. Figure 14-13 Colorblindness Colorblindness Section 14-2 Father (normal vision) Normal vision Colorblind Male Female Daughter (normal vision) Son (normal vision) Mother (carrier) Daughter (carrier) Son (colorblind) Go to Section:

37. Hemophilia is a __________________________ in which one is unable to clot their blood. • Also known as • Hemophilia is caused by a defect in a gene and the protein for normal blood clotting is missing. recessive sex-linked disorder “bleeders disease”.

39. Royal Family and Hemophilia

40. Muscular Dystrophy is another • Here the affected individual inherits a degenerative __________disorder. • The gene that codes for a _____________ is defective. They rarely live past early adulthood. • Treatments are being explored that ___________ the defective gene. sex-linked recessive disease. muscle muscle protein replace

41. shut one off III. X-Chromosomes Inactivation Males survive with only one X chromosome so, what do females do with 2? They ___________; it becomes inactive. This creates a dense region in the nucleus known as a ______________. This is seen in coat color in cats. The cells will randomly shut off the coat color allele in one X chromosome and turn them off in the other X chromosome in other cells and this leads to some areas that are spotted orange and some spotted black, creating a tricolor cat, ________. This only happens in __________ because males only have one X chromosome. Barr body calico females

42. IV. Chromosomal Disorders • Whole/sets of chromosome mutations • _______________ = failure of homologous chromosomes to separate normally during meiosis • This results in a disorder of __________________ • 2. Examples of disorders include Down’s Syndrome, Klinefelter’s, and Turner’s Syndrome Nondisjunction chromosome number

43. Nondisjunction Section 14-2 Homologous chromosomes fail to separate Meiosis I: Nondisjunction Meiosis II Go to Section:

44. Nondisjunction Section 14-2 Homologous chromosomes fail to separate Meiosis I: Nondisjunction Meiosis II Go to Section:

45. Homologous chromosomes fail to separate Meiosis I: Nondisjunction Meiosis II Nondisjunction Section 14-2 Go to Section:

46. Nondisjunction

47. 2. Examples of disorders include Down’s Syndrome, Klinefelter’s, and Turner’s Syndrome Nondisjunction disorders: Disorders in which the failure of _____________________ during one of the stages of meiosis causes a gamete to have _______________________________. Nondisjunction can occur in ___________________________. chromosome separation too few or too many chromosomes autosomes or sex chromosomes

48. Down’s Syndrome: Down’s syndrome is an example of ____________________________, specifically chromosome 21. In Down’s syndrome there is an ___________ of chromosome 21 (trisomy 21). Doing a _____________ (display of all the chromosomes in a cell nucleus) and looking at the chromosomes under a microscope detect the extra chromosome. Characteristics of Down’s syndrome include _________________, physically challenged, facial irregularities, and often heart defects. nondisjunction of an autosome extra copy karyotype mental retardation

49. Incidence of Down’s Syndrome and mother’s age

50. Turners Syndrome: Nondisjunction of the sex chromosomes in which • They have the chromosome makeup of _________ where “O” represents the missing chromosome. a chromosome is missing. 45 XO • This individual is female in appearance but does not develop the female sex organs during puberty and is ________. sterile.