Chapter 14

1. Chapter 14 • Key Concepts: • How is sex determined? • How do small changes in DNA Cause genetic disorders? The Human Genome

2. Human Chromosomes • A. Karyotype: A picture of chromosomes taken during mitosis and cut out and arranged into homologous pairs.

3. Let us review what we have previously learned

4. A Diploid Cell has ________ of homologous chromosomes. A human diploid cell has ____ chromosomes arranged in ____ pairs. two sets 46 23 Mendelian genetics requires that organisms inherit ____________of a gene from each parent. 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

5. 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). testes ovaries haploid number Fertilization zygote diploid number

6. Humans have 46 total chromosomes: 44 _________ (body) that follow regular Mendelian genetics, and 2 ________________ (X and Y). autosomes sex chromosomes

7. A pedigree chart shows the __________ within a family and can be useful to help with genetic __________ problems within families. • It is another way to _______ an outcome of a particular cross and the ________ of the family members. relationship inheritance predict genotype

8. Pedigree Figure 14-3 A 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.

14. Video Notes Worksheet: What are Pedigree Charts?

15. Video Notes Worksheet: Pedigree Analyses Guided Practice

16. Video Notes Worksheet: Pedigree Summary

17. Human Genes The ______________: Complete set of genetic information that is composed of about 30,000 genes. human genome

18. Human Traits • Phenotypes are determined by __________as well as ______________ influenced. • _____________ influences on gene expression are not ________, but genes are. genotypes environmentally Environmental inherited

19. both alleles Atrait controlled by a recessive alleleresults in adisorder being present only if _____________ are present. • Examples include: PKU (Phenylketonuria), TaySachs, Cystic Fibrosis, Albinism, and Galactosemia.

20. one allele A trait controlled by a dominant allele results in the disorder being present when only ________ is present. • Examples include: Achondroplasia (dwarfism), Hypercholesterolemia, and Huntington’s Disease

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

22. 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

23. 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

24. Codominant Alleles: controlled by _____________________________. • Sickle Cell Anemia is an example. two alleles that share dominance

25. sickle Sickle Cell Anemia The patient’s blood cells were found to be irregularly shaped, like a _____, and this is how the disease got its name. In normal red blood cells ___________carries _________and distributes it around the body. In sickle cell disease, the red blood cells are sickle–shaped, causing hemoglobin to no longer carry oxygen as well and disrupts the normal functioning of cells. hemoglobin oxygen

26. Cystic Fibrosis or “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

27. Figure 14-8 The Cause of Cystic Fibrosis Chromosome # 7 Section 14-1 CFTR gene 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. 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.

28. 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

29. 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 GUG GAG Val – His – Leu – Thr – Pro – VAL – Glu… 1 2 3 4 5 6 7 …146

30. 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

31. Sickle Cell Anemia is a __________ that has provided an _________ in Malaria prone areas. • In these areas it is _________________________ and therefore Sickle Cell Anemia persists in many heterozygous individuals since the homozygous recessive condition is lethal. mutation advantage favored by natural selection HS HA HS HS HS HA HS HA HS HA HA HA

32. 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?

33. gametes Male 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% 50% males determine the sex X Y X XX XY X XX XY

34. 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

35. 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

36. Colorblindness Figure 14-13 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. Colorblindness Figure 14-13 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:

38. 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”.

40. Royal Family and Hemophilia

41. 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

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 Homologous chromosomes fail to separate Meiosis I: Nondisjunction Meiosis II Go to Section:

44. Nondisjunction

45. 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

46. 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

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

48. 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.

49. Klinefelter’s Syndrome: Nondisjunction of the sex chromosomes in which an _____________________ is present. • They have the chromosome makeup of ________. They are ___________ in appearance and are also sterile. May also be 48 XXXY or 49 XXXXY extra X chromosome 47XXY male No nondisjunctions of the sex chromosomes have ever produced and survived without an ______________. This is because the X chromosome carries many genes X chromosome essential for life.

50. XXY condition • Results mainly from nondisjunction in mother (67%) • Phenotype is tall males • Sterile or nearly so • Feminized traits (sparse facial hair, somewhat enlarged breasts) • Treated with testosterone injections