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UNDERSTANDING HEREDITY

UNDERSTANDING HEREDITY. GENETICS AND MUTATIONS. Genetics. Part One. Genetics is…. The scientific study of heredity. A gene is…. A sequence of DNA that codes for a protein and determines traits. What is an allele?.

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UNDERSTANDING HEREDITY

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  1. UNDERSTANDING HEREDITY GENETICS AND MUTATIONS

  2. Genetics Part One

  3. Genetics is… • The scientific study of heredity

  4. A gene is… • A sequence of DNA that codes for a protein and determines traits

  5. What is an allele? • One of two or more alternative forms of a gene that are found at the same place on a chromosome.

  6. What does the term heterozygous mean? • The organism has two different alleles for a trait. • Example: Tt Bb

  7. What does the term homozygous mean? • The organism has two of the same alleles for a trait. • Example: TT or tt BB or bb

  8. Complete section determining heterozygous or homozygous genotypes

  9. What is a genotype? • The actual genetic makeup of an organism.

  10. What is a phenotype? • The physical characteristics of an organism.

  11. Complete section on phenotype/genotype

  12. Who was Gregor Mendel? • The “Father” of genetics

  13. What was his contribution? • His experiments laid the foundation of the science of genetics. • He noticed that traits could disappear in one generation and reappear in later generations.

  14. Gregol Mendel Born July 20, 1822 HeinzendorfbeiOdrau, Austrian Empire (now Hynčice, Czech Republic) Died January 6, 1884 (aged 61) Brno (Brünn), Austria-Hungary (now Czech Republic) Nationality Empire of Austria-Hungary Fields Genetics Institutions St Thomas's Abbey Alma mater University of Olomouc University of Vienna Known for Creating the science of genetics

  15. Complete section on monohybrid crosses • Now start “Practice with Crosses”

  16. Genetics Part Two

  17. Define Independent Assortment • Independent segregation of genes during the formation of gametes. • Remember: Meiosis is the formation of gametes.

  18. Define Law of Segregation • Separation of alleles during gamete formation. • Example: 1 of 2 alleles for eye color will go to each sperm or egg

  19. Define Co-dominant • Both alleles of a gene contribute to the phenotype • Examples: Type AB blood; 1 blue eye and one green eye; speckled chickens

  20. Define Incomplete Dominance • One allele cannot dominate another; the final phenotype is a blend of the 2 alleles • Example: cross a red carnation with a white carnation makes a pink carnation

  21. Co-dominance Incomplete Dominance

  22. Redefine genotype and phenotype

  23. Co-Dominance How many phenotypes are there? Three: AA,BB, AB Three How many genotypes are there?

  24. Complete examples of incomplete dominance.

  25. Incomplete dominance How many phenotypes are there? Three: RR-red rr-white Rr-pink Three How many genotypes are there?

  26. Complete examples of co-dominance.

  27. Genetics Part Three

  28. Sex chromosomes What are the male sex chromosomes? XX XY What are the female sex chromosomes?

  29. What does it mean for a trait to be sex-linked? • It is carried on one of the sex chromosomes, most likely the X

  30. Examples of sex-linked traits would be… • The ability to see color (color blindness) • Having a full head of hair (baldness) • Blood clotting properly (hemophilia)

  31. What is a di-hybrid cross? • A cross between two individuals with two different traits that you are studying • Complete examples and problems

  32. Mutations

  33. What is a mutation? • Genes code for… • Mutations are… • Proteins • Mistakes in genetic code that affect the final protein

  34. What is a point mutation? A mistake in one nitrogen base of an mRNA codon

  35. Types of point mutations: • Substitution – 1 nucleotide is switched for another Example: CAT GCA CAT GCG • Insertion or deletion – 1 nucleotide is inserted/deleted in sequence Example: CAT GCA CAT GAC A Example: CAT GCA CAT CA

  36. Effects of point mutations • Substitution • Insertions/deletions • Might have no effect on/or will only effect one amino acid • Change how the sequence is read – called a frameshift mutation

  37. epidermolysisbullosa

  38. What is a chromosomal mutation? A change in the number or structure of chromosomes.

  39. Types of chromosomal mutations • Deletion - entire gene(s) deleted • Duplication – an extra copy of gene(s) added • Inversion – segment of chromosome is flipped over and reversed in place • Translocation – segment of chromosome breaks off/relocates to another

  40. Result of: Duplication Can be the result of: Inversion, deletion or translocation

  41. When mutations go… Right Disruption of biological activities Disability Death Source of genetic variation May allow some members of a species a better chance to survive Wrong

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