Heredity

1. Heredity Mutations & Genetic Engineering Indicator B – 4.8: Compare the consequences of mutations in body cells with those in gametes. Indicator B – 4.9: Exemplify ways that introduce new genetic characteristics into an organism or a population by applying the principles of modern genetics.

2. Key Concepts • Mutation: • mutagen, mutant cell, gene mutation, chromosomal mutation, nondisjunction • Beneficial mutations • Pedigree • Genetic Engineering: • gene map, genome, cloning, gene therapy, stem cells • Selective Breeding: • Inbreeding, hybridization

3. What you already know… Students have no previous knowledge of this concept. It has not been addressed in previous grades.

4. It is essential for you to know… • A mutation is an alteration of an organism’s DNA and can range in severity. • Most mutations are automatically repaired by the organism’s enzymes, but those that are not repaired may result in altered chromosomes or genes. • Mutant body cells are not passed on to offspring but mutant gametes may be inherited. • In some cases, mutations are beneficial to organisms. • A pedigree is a chart constructed to show an inheritance pattern within a family through multiple generations. • Genetic engineering is the process of replacing specific genes in an organism in order to ensure that the organism expresses a desired trait. • Cloning, gene therapy, and hybridization are applications of genetic engineering.

5. Objectives • Compare the consequences of mutations in body cells with those in gametes. • Recall the causes of mutations. • Classify mutations as resulting from sex cell or somatic cell alterations. • Classify mutations as genetic or chromosomal. • Exemplify genetic or chromosomal disorders. • Interpret a pedigree with regard to the nature of specific traits within a family. • Exemplify ways that introduce new genetic characteristics into an organism or a population. • Recognize types of genetic engineering and selective breeding. • Summarize the purposes of the various types of genetic engineering and selective breeding. • Compare selective breeding and hybridization. • Summarize the benefits & drawbacks of the types of genetic engineering & selective breeding.

6. Vocabulary Words • Mutation • Point mutation • Frameshift mutation • Mutagen • Clone • Genetic engineering • Recombinant DNA • Transgenic • Genomics • Human Genome Project • Gene therapy • Artificial selection (selective breeding)

7. Mutations A mutation is any change in the DNA sequence that causes a change in the amino acid sequence, thus a variation in the protein.

9. Mutations • Mutations can occur many ways: • They can be inherited from the parent(s). • They can occur in an egg or sperm cell just after fertilization. • They can be acquired during the organism’s lifetime.

10. Egg Sperm Mutation Occurs Fertilized Egg Mutation Body Cells of Offspring Reproductive Bone Brain Pancreas

11. Are mutations ALWAYS passed on to offspring? • Mutations in Gametes • Can be passed on to offspring. • May result in poorly formed or nonfunctional proteins. • May be lethal. • Mutations in Somatic Cells • Not passed on to offspring. • Can interfere with cell function. • Due to mitosis, the mutation will be passed on to other cells.

12. Mutations • Two types: • Gene Mutations • Chromosomal Mutations

13. Gene Mutations • Result from changes in a single gene. • Point mutation • Occur at a single point. • A nucleotide can be substituted for another and can change the entire sequence of amino acids therefore messing with the protein.

14. Point Mutation Example:Change in the Reading Frame Normal Reading Frame: THE FLY HAD ONE RED EYE Point Mutation on Reading Frame: THE FLY HID ONE RED EYE Remember: DNARNAAmino Acidsproteins.

15. Point Mutation Example:Sickle Cell Anemia • Due to a point mutation in the Beta Globin gene. • DNA should be C T C but is actually C A C. • RNA should be G A G but is actually G U G. • This change causes a change in the amino acid. Normal hemoglobin & RBC Sickled hemoglobin & RBC

16. Gene Mutations • Frame-shift Mutation • Involves deletions and insertions of nucleotides. • Can change the entire reading frame of the codon, thus causing problems with the protein.

17. Frameshift Mutation Example:Change in the Reading Frame Normal Reading Frame: THE FLY HAD ONE RED EYE Insertion: THE FLY QHA DON ERE DEY Deletion: THE FLH ADO NER EDE YE Remember DNARNAAminoAcidsproteins. video segment

18. Chromosomal Mutations • Involves changes in the number or structure of chromosomes. • May change the locations of genes on the chromosomes and even the number of copies of some. • Four types: • Deletion • Duplication • Inversion • Translocation

21. Nondisjunction May lead to genetic disorders

22. Chromosomal mutation disorders • There are many different chromosomal mutation disorders. The following slides highlight just a few of these. They do contain images that may be hard for some students to view, so please view them with caution.

23. Trisomy Disordershaving three copies of a chromosome • http://medgen.genetics.utah.edu/photographs/pages/trisomy_13.htm • http://www.plasticsurgery4u.com/klinefelters_xxy/index.html Down Syndrome is the most recognizable of these, but there are others.

24. MonosomyHaving one copy of a chromosome Turner Syndrome Cri du Chat Syndrome http://www.genome.gov/19519119 http://www.genome.gov/19517558

25. Polyploidyhaving multiple sets of chromsomes • Polyploidy usually leads to death in animals. • Some plants are successful with extra set(s) of chromosomes. http://waynesword.palomar.edu/hybrids1.htm#watermelon

26. Are all mutations bad? In some cases mutations are beneficial to organisms. Beneficial mutations are changes that may be useful to organisms in different changing environments. These mutations result in phenotypes that are favored by natural selection and increase in population. Antibiotic resistant bacteria is an example of a beneficial mutation-at least from the point of view from the bacteria.

27. Bad Mutations • Mutations can lead to genetic disorders. • By examining a pedigree, geneticists can also see the likelihood of an individual inheriting a genetic disorder.

28. Pedigree A pedigree is a chart constructed to show an inheritance pattern within a family through multiple generations. Through the use of a pedigree chart and key, the genotype and phenotype of the family members and the genetic characteristic can be tracked.

29. Parts of a Pedigree Unaffected Female Unaffected Male Mating Unaffected male Offspring Affected female offspring Offspring

30. pedigree

31. Why not more mutations? • Changes are possible that will NOT lead to a change in the protein…not a mutation. • Mutations occur about 1/100 000 000 bases. • Wobble position: 3rd base in codon provides protection against mutation. • Ex: CCA, CCG, CCC, CCU = proline • DNA has proofreading enzymes that can repair mismatches before transcription.

32. DNA Polymerase The role of DNA polymerase is to proofread a frame before it is ready to be translated. Often, this enzyme can catch a mutation before it goes through translation, but not always. If the mutation is caught and correct, the organism will never be affected. However, if it doesn’t then the organism will be affected.

33. What Causes Mutations? • Mutagens are factors such as radiation, chemicals, ultraviolet light, etc. that can cause changes in DNA. Some are natural, others are not. Check out some mutagens....and what they do!

34. Mutagens

36. How can we cause an organism to possess a trait of another organism? Since ALL living things use DNA as their genetic material, it is possible to insert DNA from one species to another, either through a cross if the organisms are of the same species, or through recombinant DNA if the organisms are dissimilar.

37. Manipulating DNA • Scientists are now able to manipulate, or handle and change, DNA within organisms. • They are able to examine DNA on an entirely new level because of increases in technology. • They are able to change DNA or extract DNA from one organism and place it in another. However, this is not always successful.

38. Genetic Engineering • Genetic engineering the process of replacing specific genes in an organism in order to ensure that the organism expresses a desired trait. • Accomplished by taking specific genes from one organism and placing them into another organism.

39. Gene Map Genetic engineering occurs when scientists know exactly where genes occur on chromosomes. A gene map shows this.

40. Human Genome Project • Genome refers to all the genetic material in an organism. • The Human Genome Projectthat mapped the DNA sequence of human genes is useful in identifying genes for specific traits.

41. Cloning In cloning, an identical copy of a gene or an entire organism is produced. Cloning brings benefits but may also result in genetic disorders or health problems.

42. Gene Therapy In gene therapy, scientists insert normal genes into absent or abnormal genes. Once inserted, the normal gene begins to produce the correct protein or enzyme, eliminating the cause of the disorder. However, gene therapy has had limited success because the hose often rejects the injected genetic material.

44. Results of Genetic Engineering • Plants that make natural insecticides, are higher in protein, or spoil more slowly. • Animals that are bigger, are faster growing, or are resistant to disease. • Bacteria that produce hormones such as human insulin or human growth hormones. • In humans, it is theoretically possible to insert copies of normal genes into the cells of people with different genetic disorders.

45. Let’s Think… • Why would you want to selectively breed an organism? • How is selective breeding done? • What are some organisms that are often products of selective breeding?

46. Selective Breeding • Selective breeding is the method of artificially selecting and breeding only organisms with a desired trait to produce the next generation. Almost all domesticated animals and most crops have been selectively bred.

47. Pug Beagle The puggle is NOT considered to be a breed of dog. Canis familiaris Canis familiaris ***What would have to be done to make the puggle a breed? ***What evidence would we have that a new breed had been created? Canis familiaris Puggle

48. Inbreeding • In order to keep lines of breeds pure, breeders will often interbreed their organism, called inbreeding. While the line will stay pure, it may also result in many genetic disorders and problems. The drawback being recessive gene defects often show up.

49. HybridizationA form of Selective Breeding Tiger + Lion = Liger Panthera tigris x Panthera leo Top 10 Animal Hybrids http://members.diaryland.com/edit/adclick.phtml?a=709142448 http://www.eriksaunders.com/archive.FEB05.htm

50. They say that the closest relative of humans is the chimpanzee. Would a hybrid be possible? K: Animalia P: Chordata C: Mammalia O: Primates F: Homindae G: Pan S: troglodytes K: Animalia P: Chordata C: Mammalia O: Primates F: Homindae G: ? S: ? K: AnimaliaP: ChordataC: MammaliaO: PrimatesF: HominidaeG: HomoS: sapiens http://www.primarilyprimates.org/videos/index.html