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Flashcards

Th2L02 DNA damage and mutations

Usuário eliminado O usuário eliminou as informações de disciplina Inglês 42 flashcards

Th2L02 DNA damage and mutations

Flashcards do conjunto (42)

  1. 1What are the 3 forms of induced mutation and what are their main mechanisms of actionPhysical (ionising radiation) ( single or double strand breaks), UV light (causes thymine dimers) and chemical (agents that react with nuclear bases)
  2. 2What is UV-C (180-290 nm)Light found in daylight as it is absorbed by the ozone layer; the most energetic and lethal
  3. 3What is UV-B (290-320 nm)The major mutagenic fraction of sunlight
  4. 4What is damage causes by UV irradiationchemical bonds between adjacent thymines distorting DNA and causing problems during DNA replication, often resulting in point mutations
  5. 5What is Nitrous acid an example ofChemical agent that results in (CG > TA) point mutation
  6. 6What is Alkylating agents an example ofChemical agent that results in guanine modification, GC > AT
  7. 7What are Free radicals examples of (strand breaks and base modification)Chemical agent
  8. 8What are free radicals○ Unstable, highly-reactive molecules created during normal metabolism and in response to environmental factors
    ○ May play a role in the development of cancer, cardiovascular disease, and other diseases of aging by reacting with and damaging DNA and other parts of cells.
  9. 9What is Xeroderma pigmentosum (XP)a mutation that results in defects in a single strand nucleotide excision repair (NER) gene (XP-D), which prevents repair of thymidine dimers as it encodes for helicase required for NERWhat is Xeroderma pigmentosum (XP)
  10. 10What are the symptoms of Xeroderma pigmentosum (XP)Dry skin w/ melanoma and other cancers by about 1000x ("children of the night")What are the symptoms of Xeroderma pigmentosum (XP)
  11. 11What are the general characteristics of cancer cellsDo not grow old and die
    No reproductive limit
  12. 12How many mutations are sufficient to turn healthy somatic cell to a cancerous cell To the point where DNA polymerase will not recognise mutated strand5-6 mutations
  13. 13How many (%) of human primary tumours test positive for telomerase activity85%
  14. 14What kind of point mutations are there (4)• Silent (synonymous)
    • Missense (non-synonymous)
    • Nonsense
    • Indels    What kind of point mutations are there (4)
  15. 15What is a silent mutationa single point mutation that doesn't change the coded amino acid
    e.g. CGA (Arg) -> CGG (Arg)
  16. 16What is a missense (non-synonymous)a single point mutation that DOES change the coded amino acid
    e.g. Sickle cell anaemia (GAG (Glu) > GTG (Val))
    N-Ras (CAA (Gln) > CAC (His))
  17. 17What is a nonsense mutationa single point mutation that does not coded for an amino acid e.g. a STOP or START codon instead where there shouldn't be one
    TGC (amino acid codon) > TGA (stop codon) resulting in trunkated polypeptides
  18. 18What are indels (mutations)small scale insertions and deletions
  19. 19What kind of indels exist (2)Insertions/deletions with multiple of 3 that maintain of reading frame
    Insertions/deletions NOT with multiple of 3
  20. 20loss of 508th codon in CFTR > cystic fibrosis when homozygous is an example of what kind of mutationInsertions/deletions with multiple of 3 that maintain of reading frame
  21. 21Which mutation results in frame shifts resulting in non-native polypeptides which can be catastrophicInsertions/deletions NOT with multiple of 3
  22. 22What is Huntington's disease an example ofSerious consequences of small scale insertion/deletion
    namely:
    Trinucleotide CAG (glutamine) repeat on huntingtin gene (from 10-34) to (36-121) > neuronal decay
  23. 23What happens as a result of loss of 32bp in CCR5Individuals homozygous for change in 32 CCR5 allele are resistant to HIV-1
  24. 24What is CCR5The binding receptor HIV goes for on macrophage
  25. 25What is cri du chatA chromosomal deletion in chromosome 5p that results in children who are mentally retarded, have small heads, and have a cry that sounds like a loud cat
    The children die at a young age    What is cri du chat
  26. 26What is Chronic myelogenous leukaemia (CML)A genetic disease due to translocation where a portion of chromosome 22 gets swapped with a piece of chromosome 9 resulting in a Philadelphia Chromosome
    Its a cancer affecting white blood cells    What is Chronic myelogenous leukaemia (CML)
  27. 27What are the 3 examples of spontaneous mutation- errors in DNA replication which escape proofreading and repair mechanisms
    - replication slippage
    - deamination
  28. 28What is replication slippageGain of repeats - reverse slippage
    Loss of repeats - forward slippage    What is replication slippage
  29. 29What is deamination○ The removal of an amino group from an organism, particularly from an amino acid
    ○ C will then pair with A and A will then pair with C, e.g.    What is deamination
  30. 30What causes human immunodeficiency virus (HIV)an
    enveloped RNA retrovirus infects CD4 T cells and uses the enzyme reverse transcriptase to mediate synthesis of proviral DNA which integrates into the host cell genome
  31. 31What do CD4 T cells doRecognises and binds to MHC II antigens and helps stabilise the binding of antigenic determinants to T cell receptor
  32. 32What do the high mutations rate of HIV genome result indrug resistant viruses
  33. 33What do early HIV symptoms resembleInfluenza:
    Fever
    Chills
    Rash
    Night sweats
    Muscle aches
    Sore throat
    Fatigue
    Swollen lymph nodes
    Mouth ulcers
  34. 34What does Azidothymidine (AZT) doInhibits multiplication of HIV and other retroviruses by blocking reverse transcription and production of virally encoded DNA
  35. 35What is the main issue with Azidothymidine (AZT)Eventually patients stopped responding to treatment
  36. 36What is the HIV mutation rate10^-3 per base
    One of the highest of any virus (or anything else) observed to date
    1 x 10^6 faster than human genome
  37. 37What is the typical mutation rate of a eukaryotic genome10^-9 per base
  38. 38What is reverse transcriptaseAn DNA polymerase enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis
  39. 39What features of reverse transcriptase make it so lethal (2)• More error prone their other nucleic acid polymerases
    • Does not possess an exonuclease 3' to 5' so does not have any proofreading capacity
  40. 40What is Acute myeloid leukaemia• A cancer of the blood in which a person produces faulty white blood cells
    • Immature white blood cells are overproduced and they crowd the bone marrow and cause it not to make normal blood cells    What is Acute myeloid leukaemia
  41. 41What do all forms of AML have in commonthe same 9 mutations
  42. 42Which genes are mutated in AML (3)oncogenes, tumour suppressors and novel genes

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O usuário eliminou as informações de disciplina FlashCards sobre Th2L02 DNA damage and mutations, criado por Usuário eliminado em 26-08-2016.
Criado por
Usuário eliminado · ago 2016
Atualizado
27 ago 2016
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23
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  • Criado por Emma Allde · 21 ago 2016
  • Copiado por Emma Allde · 26 ago 2016
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