Bio 130 CH 14

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  1. A heritable change in the genectic material. Essential to continuity of life and a source of variation for natural selection.
  2. New mutations are more likely to be harmful that beneficial so hwat is in place to counter it?
    DNA repair systems.
  3. Gene mutations may affecr amino aciud sequences. What are the ways?
    Silent mutation, Missense mutation, nonsense mutaion, and frameshift mutation
  4. this mutation does not alter the maino acid sequence amd os due do degeneracu of genetic code.
    Silent mutation
  5. This mutation Changes a single amino acid in a polypeptide. May not alter function is substituted amino acid is similar in chemistry to original. ex Sickle cell
    Missense mutation
  6. This mustation is a change from a normal codon to a stop codon. Produces a truncated polypeptide.
    Nonsense mutation
  7. This mutation is an addition or deletion of nucleotides and creates a completely different amino acid sequence downstream from mutation.
    Framshift mutation
  8. A mutation may alter the sequence within a promoter and affect the rate of transcription. What will this cause?
    It may enhance or inhibit transcription
  9. Mutations may occur in other regulatory elements or operator sites. what does this cause?
    May alter DNA sequence of operator so that repressor protein does not bind
  10. What determines the severity and heritability of a mutation?
    Time and location
  11. these cells give rise to gametes
    germ-line cells
  12. These are all cells in the body
    somatic cells
  13. in Germ-line cells where does the mutation occur?
    In sperm, egg, or in gamete progenitor cells
  14. In somatic cells wher doe sthe mutation occur?
    early or late development. gives a genetic mosaic with patches of mutamt tissue
  15. These mutations are From abnormalities in biological processes. Rates vary species to species and gene to gene. Background mutation rate ~1 mutation / million genes
    Spontaneous mutations
  16. these mutations are caused by environmental agents
    Induced mutations
  17. chemical or physical agents that alter DNA
  18. How do mutagens work?
    They can disrupt base pairing by changing a c to u for ex. dsrupt replication by adding something between bases such has benzoyrene. also radiation causing deletions or gaps
  19. This radiation has high energy and penetrates deeply to create free radicals. X rays and gamma rays. Cause deletions or breaks in one or both DNA strands
    Ionizing radiation
  20. This radiation has less energy and can only penetrate the surface. UV rays can cause formation of thymine dimers, causing gaps or incorporation of incorrect bases
    Nonionizing raditation
  21. Uses Salmonella typhimurium that cannot synthesize histidine due to a point mutation. ? Test monitors rate at which second mutation occurs.
    Ames test
  22. All organisms require the ability to repair DNA. What are the two components?
    Detection of damage and repair of damage
  23. What are the types of repair?
    Direct repair, nucleotide excision repair, and methy-directed mismatch repair
  24. in this repair A repair enzyme recognizes an incorrect structure in the DNA and directly converts it back.
    direct repair
  25. in this repair portion of DNA strand containing an abnormal nucleotide is removed and replaced.
    Nucleotide excision repair. (NER)
  26. in this repair a base pair mismatch is detected and a stran of surrounding DNA is removed and replaced
    Methyl-directed mismatch repair
  27. What is the most common repair system?
    NER nucleotide excision repair
  28. What where the diseases that led to the discovery of NER?
    Xeroderma pigmentosum (XP), Cockayne’s syndrome (CS), PIBIDS
  29. 90% of cancers are due to exposure. About what percent is from carcinogens?
  30. Can migrate to other parts of the body
  31. An oncogene may promote cancer by keeping the cell division signaling pathway in a permanent
    on position
  32. Oncogenic mutations may decrease ability of Ras to hydrolyze GTP or exchange GDP/GTP faster. What does this cause?
    Both keep signaling pathways constantly open
  33. What is a proto-oncogene?
    A normal gene that, if mutated, can become an oncogene.
  34. What are the four common genetic changes?
    Missense mutations, gene amplifications, chromosomal translocations, and retroviral insertions.
  35. this mutation Increase in copy number results in too much protein
    Gene amplifications
  36. In this mutation Two chromosomes break and switch ends. Very specific translocations associated with certain types of tumors. Can create chimeric genes
    Chromosomal translocations
  37. What are the two ways that viruses cause cancer?
    modifying host dna and carry oncogenes
  38. What are the typical functions of tumor-supressor genes
    prevent cancerous growth, maintain genome integrity, and ihibitor of cell division
  39. Proteins called cyclins and cyclin-dependent protein kinases (cdks) are responsible for advancing a cell through the four phases of the cell cycle. what are these called?
    checkpoint proteins
  40. about 50% of all human cancers are associated with defects in this gene
  41. function as proteases that digest selected cellular proteins causing the cell to break down . It is beneficial for a multicellular organism to kill an occasional cell with cancer causing potential
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Bio 130 CH 14
2015-10-29 19:55:04
bio 130

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