1. Copyright © 2009 Pearson Education, Inc. © 2013 Pearson Education, Inc. PowerPoint Lecture prepared by Jill Feinstein Richland Community College Fourth Edition BIOLOGY Science for Life | with Physiology Colleen Belk Virginia Borden Maier Chapter 6 DNA Detective Complex Patterns of Inheritance, and DNA Fingerprinting

2. © 2013 Pearson Education, Inc. 1 Extensions of Mendelian Genetics  Incomplete Dominance is when a heterozygote expresses a phenotype intermediate between both alleles.  For example, RR produces red flowers, Rr produces pink flowers and rr produces white flowers  Codominance is when two alleles are expressed at the same time.  ABO blood type is an example of this with both the dominant A and B being expressed in a type AB person.  Multiple allelism occurs when there are more than two alleles of a gene.  ABO blood types exhibit this.

3. © 2013 Pearson Education, Inc. 1 Extensions of Mendelian Genetics  ABO blood group has three alleles of one gene:  I A and I B are codominant to each other; i is recessive to both other alleles.  An individual will have two of these alleles.

4. © 2013 Pearson Education, Inc. 1 Extensions of Mendelian Genetics  Another blood group is called the Rh factor.  Rh + is caused by a dominant allele.  Rh + Rh + or Rh + Rh -  Rh - is caused by 2 recessive alleles.  Rh - Rh -  Blood typing can be used to exclude potential parents.  E.g., an AB parent can never have an O child and two Rh - parents can never have a Rh + child.  See Table 8.2 for compatibilities of blood types.

5. © 2013 Pearson Education, Inc. 1 Extensions of Mendelian Genetics  Pleiotropy is the ability of a single gene to cause multiple effects on the individual’s phenotype.  Hemophilia is an example of pleiotropy.  The inability to clot blood normally due to the absence of a clotting factor  Gene for this clotting factor is on the X chromosome  Prince Alexis suffered from this and inherited the hemophilia allele from his mother

6. © 2013 Pearson Education, Inc. 2 Sex Determination and Sex Linkage  Humans have 22 pairs of autosomes and one pair of sex chromosomes  Women: two X chromosomes  Men: one X and one Y chromosome

7. © 2013 Pearson Education, Inc. 2 Sex Determination and Sex Linkage  Sex-linked genes: genes located on the sex chromosomes  X-linked: located on the X chromosome  Y-linked: located on the Y chromosome  SRY gene which leads to the development of the testes  Males always inherit their X from their mother  Males are more likely to express recessive X-linked traits than females due to carrying only 1 X.  Females are less likely to express X-linked traits since they have to have 2 copies of the bad X’s.

8. © 2013 Pearson Education, Inc. 2 Sex Determination and Sex Linkage  Only females can be carriers of X-linked recessive traits.  Carriers express the normal trait but are heterozygous, so they carry the allele for the recessive trait.  Hemophilia, red-green color blindness, and Duchenne Muscular dystrophy are example of X-linked traits.

9. © 2013 Pearson Education, Inc. 2 Sex Determination and Sex Linkage  X inactivation guarantees that all females receive only 1 dose of the proteins by the X chromosomes.  Inactivation is irreversible and inherited during cell division.  It is caused by RNA wrapping around the X chromosome.

10. © 2013 Pearson Education, Inc. AnimationAnimation: X-Linked Recessive Traits Click “Go to Animation” / Click “Play”

11. © 2013 Pearson Education, Inc. 3 Pedigrees  Pedigree: a family tree, showing the inheritance of traits through several generations  Symbols commonly used in pedigrees are circles and squares

12. © 2013 Pearson Education, Inc. 3 Pedigrees  Pedigrees reveal modes of inheritance  Pedigree for an autosomal dominant trait:

13. © 2013 Pearson Education, Inc. 3 Pedigrees  Pedigree for an autosomal recessive trait:

14. © 2013 Pearson Education, Inc. 3 Pedigrees  Pedigree for an X-linked trait:

15. © 2013 Pearson Education, Inc. 3 Pedigrees

16. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  No two individuals are genetically identical except for identical twins.  Small differences in nucleotide sequences of their DNA  This is the basis for DNA fingerprinting  Unambiguous identification of people  When sample size is small it is necessary to copy the genetic material to increase the quantity available for testing.

17. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  Small amounts of DNA can be amplified using PCR (polymerase chain reaction)  DNA is mixed with nucleotides, specific primers, Taq polymerase, and then is heated  Heating splits the DNA molecules into two complementary strands  Taq polymerase builds a new complementary strand  DNA is heated again, splitting the DNA and starting a new cycle.

18. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  Each cycle, the amount of DNA doubles.

19. © 2013 Pearson Education, Inc. AnimationAnimation: Polymerase Chain Reaction (PCR) Click “Go to Animation” / Click “Play”

20. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  DNA is cut into fragments using restriction enzymes, which cut around DNA sequences called VNTRs (variable number tandem repeats).

21. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  Gel electrophoresis separates DNA fragments on basis of their sizes Gel electrophoresis  Electric current is applied to an agarose gel  Smaller fragments run faster through the gel  Fragments are transferred to a sheet of filter paper  Labeled probe reveals locations of fragments containing VNTRs

22. © 2013 Pearson Education, Inc. 4 DNA FingerprintingDNA Fingerprinting  Each person’s set of fragments is unique.  All of a child’s bands must be present in one or both of the parents.

23. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  Pedigree of Romanov family

24. © 2013 Pearson Education, Inc. 4 DNA Fingerprinting  To see if parents and their children were Romanovs, DNA fingerprints were prepared for relatives of tsar and tsarina.  Adult male skeleton (related to the children) was related to George, the tsar’s brother.  Adult female skeleton (related to the children) was related to Prince Philip, the tsarina’s grand- nephew.  Conclusion: the grave contained the tsar, tsarina, three of their children, and four servants.

25. © 2013 Pearson Education, Inc. Which forensic technique was used to determine the identity of the Romanovs?  examining fingerprints  ballistic (firearm) evidence  DNA fingerprinting  toxicology

26. © 2013 Pearson Education, Inc. Which forensic technique was used to determine the identity of the Romanovs?  examining fingerprints  ballistic (firearm) evidence  DNA fingerprinting  toxicology

27. © 2013 Pearson Education, Inc. Snapdragon color is an example of incomplete dominance. If you cross a red snapdragon with a white snapdragon, what will the offspring look like?  All of the offspring will be red.  All of the offspring will be white.  All of the offspring will be pink.  Half the offspring will be red and half will be white.

28. © 2013 Pearson Education, Inc. Snapdragon color is an example of incomplete dominance. If you cross a red snapdragon with a white snapdragon, what will the offspring look like?  All of the offspring will be red.  All of the offspring will be white.  All of the offspring will be pink.  Half the offspring will be red and half will be white.

29. © 2013 Pearson Education, Inc. Coat color of cattle displays codominance. A red coated cattle is bred with a white coated cattle. What color coat will their offspring have?  Red coatC. Pink coat  White coatD. Red and white coat

30. © 2013 Pearson Education, Inc. Coat color of cattle displays codominance. A red coated cattle is bred with a white coated cattle. What color coat will their offspring have?  Red coatC. Pink coat  White coatD. Red and white coat

31. © 2013 Pearson Education, Inc. Which genetic term best describes how the ABO blood system is inherited?  codominance  incomplete dominance  pleiotropy  X-inactivation

32. © 2013 Pearson Education, Inc. Which genetic term best describes how the ABO blood system is inherited?  codominance  incomplete dominance  pleiotropy  X-inactivation

33. © 2013 Pearson Education, Inc. Who is more likely to suffer from colorblindness, a disorder caused by a recessive allele on the X- chromosome?  males  females  babies  the elderly

34. © 2013 Pearson Education, Inc. Who is more likely to suffer from colorblindness, a disorder caused by a recessive allele on the X- chromosome?  males  females  babies  the elderly

35. © 2013 Pearson Education, Inc. Which of the following disorders is carried on the X chromosome and is considered pleiotrophic?  Huntington's disease  Cystic Fibrosis  Hemophilia  Tay-Sachs

36. © 2013 Pearson Education, Inc. Which of the following disorders is carried on the X chromosome and is considered pleiotrophic?  Huntington's disease  Cystic Fibrosis  Hemophilia  Tay-Sachs

37. © 2013 Pearson Education, Inc. What type of trait does this pedigree show?  recessive trait  sex-linked trait  dominant trait  codominant trait

38. © 2013 Pearson Education, Inc. What type of trait does this pedigree show?  recessive trait  sex-linked trait  dominant trait  codominant trait

39. © 2013 Pearson Education, Inc. Why is Taq polymerase used instead of human DNA polymerase?  Taq polymerase is resistant to high temperatures.  Taq polymerase is resistant to high pH levels.  Taq polymerase is resistant to low temperatures.  Taq polymerase is resistant to low pH levels.

40. © 2013 Pearson Education, Inc. Why is Taq polymerase used instead of human DNA polymerase?  Taq polymerase is resistant to high temperatures.  Taq polymerase is resistant to high pH levels.  Taq polymerase is resistant to low temperatures.  Taq polymerase is resistant to low pH levels.

41. © 2013 Pearson Education, Inc. Gel electrophoresis separates DNA fragments based on _______.  Shape  pH  Number of strands  Size

42. © 2013 Pearson Education, Inc. Gel electrophoresis separates DNA fragments based on _______.  Shape  pH  Number of strands  Size

43. © 2013 Pearson Education, Inc. ______ is used to amplify DNA.  PCR  Gel electrophoresis  RFLP  VNTR

44. © 2013 Pearson Education, Inc. ______ is used to amplify DNA.  PCR  Gel electrophoresis  RFLP  VNTR