Understanding Complex Inheritance and Human Heredity

2. Chapter 11 Complex Inheritance and Human Heredity Section 1: Basic Patterns of Human Inheritance Section2: Complex Patterns of Inheritance Section 3: Chromosomes and Human Heredity

3. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Recessive Genetic Disorders • A recessive trait is expressed when the individual is homozygous recessive for the trait.

4. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Cystic Fibrosis • Affects the mucus-producing glands, digestive enzymes, and sweat glands • Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat. • Without sufficient chloride ions in the cells, a thick mucus is secreted.

5. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Albinism • Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes • White hair • Very pale skin • Pink pupils

6. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Tay-Sachs Disease • Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides • Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration.

7. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Galactosemia • Recessive genetic disorder characterized by the inability of the body to digest galactose.

8. These diseases are caused when an individual is homozygous dominant or heterozygous In order to NOT HAVE THESE DISEASES the normal person is homozygous recessive Dominant Genetic Disorders

9. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Dominant Genetic Disorders • Huntington’s disease affects the nervous system. • Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short. (this is a type of dwarfism)

10. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance

11. Complex Inheritance and Human Heredity Chapter 11

12. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Pedigrees • A diagram that traces the inheritance of a particular trait through several generations of the same family

13. Complex Inheritance and Human Heredity Chapter 11 11.1 Basic Patterns of Human Inheritance Inferring Genotypes • Knowing physical traits can determine what genes an individual is most likely to have. Scientists can determine if a trait is dominant or recessive Predicting Disorders • Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.

14. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Incomplete Dominance • The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes. (it is a mix of physical appearance between the dominant and the recessive)

15. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Codominance • Both alleles are expressed in the heterozygous condition.

16. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sickle-cell Disease Normal red blood cell • Changes in hemoglobin cause red blood cells to change to a sickle shape. • People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell 7766x

17. In Africa there is a high number of people who have the sickle-cell allele. People who are heterozygous for sickle-cell have a higher resistance to malaria. They go on to reproduce and pass on the sickle-cell trait. Sickle-cell disease and Malaria

18. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Multiple Alleles • Blood groups in humans (this shows both multiple alleles and codominance) • ABO blood groups have three forms of alleles.

19. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Coat Color of Rabbits • Multiple alleles can demonstrate a hierarchy of dominance. • In rabbits, four alleles code for coat color: C, cch, ch,and c. • C>cch> ch>c (this shows that one is dominant to the next with “c” being least dominant) • There are 10 possible genotypes and four phenotypes for rabbit fur color

20. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Coat Color of Rabbits Chinchilla Albino Light gray Dark gray Himalayan

21. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Epistasis • Variety is the result of one allele hiding the effects of another allele. eebb eeB_ E_bb E_B_ Dark pigment present in fur No dark pigment present in fur

22. There are two sets of alleles (“E” and “B”) that determine whether the fur will be dark or not. If the dog has Ee or EE it will make the fur color dark (it is written as Eebb or EEbb) If the dog has ee then the fur coat will be light (eebb, eeBb, eeBB) and produce a yellow coat Labrador Coat Color

23. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sex Determination • Sex chromosomesdetermine an individual’s gender. • Autosomes are all the other chromosomes that determine everything else. (ie. Body cells)

24. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Dosage Compensation • The X chromosome carries a variety of genes that are necessary for the development of both females and males. (Thus, it is larger than the Y chromosome) • The Y chromosome mainly has genes that relate to the development of male characteristics.

25. Chromosome inactivation Coat color of the calico cat is determined by which X chromosome is deactivated. If the X chromosome that carries the dark coat color is inactivated, the cat will have orange coloring. If the X chromosome that carries the orange coat color is inactivated, the cat will have black spots. Barr bodies: the inactivated X chromosome in females

26. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sex-Linked Traits • Genes located on the X chromosome that control traits • Since males have only 1 X chromosome they are affected by recessive X-linked traits • Females are less likely to express a recessive trait because she has two X chromosomes. One of the X chromosomes can mask the affect of the trait. Sex-Linked Traits

27. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Sex-Linked Traits • Red-green color blindness This is a recessive X-linked trait. A male only needs one copy of this allele in order to be colorblind. A female would need to have two copies of the recessive allele. Thus it is very rare to find a color blind female. Sex-Linked Traits

28. Another recessive sex-linked disorder characterized by delayed clotting of the blood. Very rare in females because she would need to have both X chromosomes with the recessive trait. Hemophilia

29. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Polygenic Traits • Polygenic traits arise from the interaction of multiple pairs of genes. This is really how height, eye color and fingerprints are inherited.

30. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Environmental Influences on phenotype • Environmental factors • Diet and exercise • Sunlight and water (flowering in plants) • Temperature (arctic fox)

31. Complex Inheritance and Human Heredity Chapter 11 11.2 Complex Patterns of Inheritance Twin Studies • Helps scientists separate genetic contributions from environmental contributions • Traits that appear frequently in identical twins are at least partially controlled by heredity. • Traits expressed differently in identical twins are strongly influenced by environment.

32. Complex Inheritance and Human Heredity Chapter 11 11.3 Chromosomes and Human Heredity Karyotype Studies • Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size. • Images of chromosomes stained during metaphase • Chromosomes are arranged in decreasing size to produce a micrograph.

33. Complex Inheritance and Human Heredity Chapter 11 11.3 Chromosomes and Human Heredity Telomeres • Telomere caps consist of DNA associated with proteins. • Serves a protective function for the structure of the chromosome • They might also be involved in aging and cancer

34. Complex Inheritance and Human Heredity Chapter 11 11.3 Chromosomes and Human Heredity Nondisjunction • Cell division during which sister chromatids fail to separate properly • If this occurs during Meiosis I or II then the resulting gametes will not have the correct number of chromosomes • Down syndrome: nondisjunction occurred on chromosome 21. • The result is short stature, heart defects, and mental disability

35. Nondisjunction occurs in both autosomes (body cells) and in gametes Nondisjunction

36. 0 Centromere Sister chromatids Pair of homologous chromosomes 5

37. 0

38. Complex Inheritance and Human Heredity Chapter 11

39. Complex Inheritance and Human Heredity Chapter 11 Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding feature.

40. A B C D Complex Inheritance and Human Heredity Chapter 11 CDQ 1 Chapter Diagnostic Questions Identify the disease characterized by the absence of melanin. albinism cystic fibrosis galactosemia Tay-Sachs

41. A B C D Complex Inheritance and Human Heredity Chapter 11 CDQ 2 Chapter Diagnostic Questions An individual with Tay-Sachs disease would be identified by which symptom? excessive mucus production an enlarged liver a cherry-red spot on the back of the eye vision problems

42. A B C D Complex Inheritance and Human Heredity Chapter 11 CDQ 3 Chapter Diagnostic Questions Under what circumstances will a recessive trait be expressed? A recessive allele is passed on by both parents. One parent passes on the recessive allele. The individual is heterozygous for the trait. There is a mutation in the dominant gene.

43. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 1 11.1 Formative Questions Which of Dr. Garrod’s observations about alkaptonuria was most critical to his determination that it is a genetic disorder? It appears at birth and runs in families. It is linked to an enzyme deficiency. It continues throughout a patient’s life, affecting bones and joints. It is caused by acid excretion and results in black urine.

44. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 2 11.1 Formative Questions Which is the genotype of a person who is a carrier for a recessive genetic disorder? DD Dd dd dE

45. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 3 11.1 Formative Questions Albinism is a recessive condition. If an albino squirrel is born to parents that both have normal fur color, what can you conclude about the genotype of the parents? at least one parent is a carrier both parents are carriers both parents are homozygous recessive at least one parent is homozygous dominant

46. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 4 11.2 Formative Questions When a homozygous male animal with black fur is crossed with a homozygous female with white fur, they have offspring with gray fur. What type of inheritance does this represent? dosage compensation incomplete dominance multiple alleles sex-linked

47. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 5 11.2 Formative Questions Of the 23 pairs of chromosomes in human cells, one pair is the _______. autosomes Barr bodies monosomes sex chromosomes

48. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 6 11.2 Formative Questions Which is an example of a polygenic trait? blood type color blindness hemophilia skin color

49. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 7 11.3 Formative Questions What does a karyotype show? The blood type of an individual. The locations of genes on a chromosome. The cell’s chromosomes arranged in order. The phenotype of individuals in a pedigree.

50. A B C D Complex Inheritance and Human Heredity Chapter 11 FQ 8 11.3 Formative Questions What is occurring in this diagram? multiple alleles nondisjunction nonsynapsis trisomy