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11.1 BASIC PATTERNS OF HUMAN INHERITANCE

11.1 BASIC PATTERNS OF HUMAN INHERITANCE. WHAT YOU WILL LEARN -How to determine if an inherited trait is dom/rec -Examples of DOMINANT/RECESSIVE disorders -Construct / Interpret PEDIGREES. READING Q ’ s. 1-IDENTIFY

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11.1 BASIC PATTERNS OF HUMAN INHERITANCE

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  1. 11.1 BASIC PATTERNS OF HUMAN INHERITANCE WHAT YOU WILL LEARN -How to determine if an inherited trait is dom/rec -Examples of DOMINANT/RECESSIVE disorders -Construct / Interpret PEDIGREES

  2. READING Q’s 1-IDENTIFY -Check the term that describes the genotype of a person who expresses a recessive trait -HOMOZYGOUS: organism with 2 of the same alleles for a particlular trait -aa

  3. READING Q’s 2-CATEGORIZE: The following genetic disorders as RECESSIVE or DOMINANT a-albinism recessive dominant b-Huntington's recessive dominant c-cystic fibrosis recessive dominant

  4. READING Q’s 3-EXPLAIN -For what purpose is a genetic pedigree used? -study genetic relationships -trace inheritance of a trait generation to generation

  5. READING Q’s 4-DRAW The symbols that are used to represent a male AND female in a pedigree MALE- FEMALE-

  6. READING Q’s 5-EVALUATE -Circle the carriers in the second generation

  7. READING Q’s 6-CALCULATE -What percentage of the children in this family inherited Tay-Sachs disease? -1/4=25%

  8. READING Q’s 7-IDENTIFY -Do any grandchildren in this family have polydactyly? -NO

  9. READING Q’s 8-EXPLAIN -Why are recessive traits difficult to study? -Not all people who carry the recessive allele have the trait

  10. GROUP WORK: APPLICATION NOTES -As a group complete the areas below using your knowledge from the reading/discussion. MAIN IDEA REVIEW VOCAB RECESSIVE / DOMINANT GENETIC DISORDERS VOCAB -carrier -pedigree

  11. MAIN IDEA -PEDIGREESinheritance of traits over several generations

  12. REVIEW VOCAB DEFINE: gene -segment of DNA on chromosome DEFINE: homozygous -2 identical alleles [TT / tt] DEFINE: heterozygous -2 different alleles [Tt]

  13. RECESSIVE/DOMINANT GENETIC DISORDERS COMPARE/CONTRAST: recessive and dominant genetic disorders RECESSIVE -expressed when indv HOMO recessive [tt] DOMINANT -expressed when indv HOMO dominant [TT] or HETERO [Tt]

  14. RECESSIVE/DOMINANT GENETIC DISORDERS EXPLAIN why recessive disorders are more common than dominant disorders. -DOMINANT: only one allele must be inherited to be affected -if DOM trait interferes w/ survival- no pass on -RECESSIVE: carriers do NOT display the disorder -many carriers are unaware they carry an affected gene

  15. RECESSIVE/DOMINANT GENETIC DISORDERS IDENTIFY: the disease for each dominant/recessive disorders -caused by altered genes; results in lack of skin pigmentation -ALBINISM -RECESSIVE -characterized by body’s inability to tolerate galactose -GALATOSEMIA -RECESSIVE -gene found on chromosome 15;characterized by lack of enzyme that breaks down fatty acids -TAY SACHS -RECESSIVE

  16. RECESSIVE/DOMINANT GENETIC DISORDERS IDENTIFY: the disease for each dominant/recessive disorders -affects the nervous system; no treatment; breaks down part of brain -HUNINGTON’S -DOMINANT -affects mucus-producing glands, digestive enzymes, sweat glands -CYCTIC FIBROSIS -RECESSIVE -affects height and body size -ACHONDROPLASIA -DOMINANT

  17. F f RECESSIVE/DOMINANT GENETIC DISORDERS F f FF Ff PREDICT: what are the chances of 2 carriers of cystic fibrosis having a child with cystic fibrosis? ¼= 25% Ff ff

  18. RECESSIVE/DOMINANT GENETIC DISORDERS Positive Exposure Positive exposure video clip Rick Guidotti - PART 2 Positive Exposure Inside Edition Part I - YouTube

  19. PEDIGREE BASICS [the FAMILY TREE of genetics] WHAT is it: -diagram explaining genetic history WHO uses it: -scientist -genetic counselors WHY use it: -probability of child having disorder/condition -determine disorder/condition as autosomal/sex linked

  20. MALE -sqaure - FEMALE -circle - AFFECTED MALE -shaded square - AFFECTED FEMALE -shaded circle - CARRIER -half shaded symbol - / PARENTS/OFFSPRING -line down from parent, circles/squares on second row PARENTS -circle joined to square - GENERATIONS -I, II , III, IV, V PEDIGREES SUMMARIZE: pedigree symbols

  21. STEPS for INTERPRETING PEDIGREES 1- DETERMINE if the pedigree chart is showing: AUTOSOMAL or X-LINKED disorder -autosomal: -If it is a 50/50 ratio between men and women -x-linked: -If most of the males in the pedigree are affected 2- DETERMINE if disorder is DOMINANT or RECESSIVE -dominant: -one of the parents must have the disorder. -recessive -neither parent has to have the disorder because they can be heterozygous.

  22. Connecting Pedigree Symbols • Married Couple • Siblings

  23. EX- PEDIGREE CHART

  24. PRACTICE INTERPRETING • Determine if the pedigree chart shows an autosomal or X-linked disease. -If most of the males in the pedigree are affected the disorder is X-linked -If it is a 50/50 ratio between men and women the disorder is autosomal.

  25. PRACTICE: Interpreting • Is it Autosomal or X-linked?

  26. Answer • Autosomal

  27. Interpreting a Pedigree Chart • Determine whether the disorder is dominant or recessive -If the disorder is dominant, one of the parents must have the disorder. -If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.

  28. PRACTICE: Interpreting • Dominant or Recessive?

  29. Answer • Dominant

  30. PRACTICE: Interpreting • Dominant or Recessive?

  31. Answer • Recessive

  32. ANALYZING PEDIGREES EVALUATE: the inheritance of achondroplasia shown in the pedigree -parent w/ disorder -father -#children with disorder -1 / 1st born son -genotype of younger son -homozygous recessive / aa

  33. ANALYZING PEDIGREES X ANALYZE and RESPOND: -RECALL if the trait is rec or dom based on the following information: -individuals I-1 and I-2 are unaffected but have affected child RECESSIVE DOMINANT -SPECIFIY if parents II-1 and II-2, who have an affected child, are carriers of that trait CARRIER NOT A CARRIER -TELL whether there is a dominant gene in the genotype of II-4 NONE A LEAST ONE -Individual II-1is in generation 2 TRUE FALSE X X X

  34. X ANALYZING PEDIGREES MANY X THINK BACK and RESPOND: -A scientist uses a pedigree to study family history TRUE FALSE -A pedigree traces the inheritance of a particular trait through only two generations TRUE FALSE -In a pedigree, one who does not express the trait is represented by a darkened circle/square TRUE FALSE -In a pedigree, a horizontal like between 2 symbols shows that these individuals are the parents of the offspring TRUE FALSE X X

  35. ANALYZING PEDIGREES DIAGRAM: Suppose both parents can roll their tongues but their son cannot. [TONGUE ROLLING = DOMINANT / T] DRAW a pedigree showing this trait LABEL each symbol with the appropriate genotype What was the probability that they would have a non-tongue roller offspring? (hint: punnet square) -both parents carry recessive gene -parent genotype Tt -son genotype tt -probability of child tt= 25%

  36. PEDIGREE CHART PRACTICE

  37. PEDIGREE PRACTICE A

  38. PEDIGREE PRACTICE B

  39. PEDIGREE PRACTICE C

  40. PEDIGREE PRACTICE D

  41. INVESTIGATING HUMAN PEDIGREES -USE the information provided in the transcript to construct a pedigree showing hairy earlobes* in a family *HE -DETERMINE the oldest couple in the family -DRAW their pedigree symbols—include names -CONTINUE with other members in the family -DETERMINE genotypes as you gather enough information

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