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biochemistry

Mohamed Ayman 10 preguntas

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Preguntas del test (10)

  1. 1An enzyme needed in base excision repair is :
    1. AGlycosylase
    2. BExcinuclease
    3. CExonuclease
    4. DPhotolyase
  2. 2Thymine dimers are reversed by
    1. APhotolyase.
    2. BGlycosylase
    3. CAP lyases
    4. DEndonuclease
  3. 3Telomeraes are complex of DNA and protein that protect the ends of linear chromosomes. In most normal human somatic cells , telomerase shorten with each division .In stem cells and in cancer cells ,however, telomeric length is maintained.
    In the synthesis of telomeres :
    1. Atelomerase , aribonucleoprotein, provides both the RNA and the polymerase needed for synthesis .
    2. Bthe RNA of telomerase serves as a primer .
    3. Cthe polymerase of telomerase is a DNA- directed DNA polymerase .
    4. Dthe direction of synthesis is 3' to 5' .
  4. 4Proteins involved in extending a replication bubble are
    1. ADNA helicases
    2. Bsingle strand binding proteins
    3. Cligase
    4. DDNA topoisomerase
  5. 5Enzyme ,responsible for proofreading base pairing is
    1. ADNA polymerase
    2. Btelomerase
    3. Cprimase
    4. DDNA ligase
  6. 6The product of irradiation of DNA by ultraviolet light
    1. AIs the cleavage of the phosphodiester back bone
    2. BRepaired by nucleotide excision repair.
    3. CProduces dimers between thymidine residues located on opposite strands of the DNA helix. d- Requires the action of a uracil glycosylase for repair.
  7. 7Patient with xeroderma pigmentosum suffer from DNA damage when they are exposed to UV light because UV light causes the formation of : a- Purine dimers in DNA
    1. APyrimidine dimers in DNA
    2. BDeoxyribose dimers in DNA
    3. CAnhydride bonds between phosphate groups in DNA
    4. DPolymerization of three DNA strand
  8. 8hereditary nonpolypois colorectal cancer(HNPCC)is the result of defects in
    1. Adirect repair.
    2. Bnucleotide-excision repair
    3. Cbase-excision repair.
    4. Dmethyl directed repair(mismatch repair)
  9. 9in a DNA molecule
    1. Athe amount of adenine and thymine = the amount of guanine and cytosine
    2. BThe amount of cytosine and guanine = the amount of adenine and cytosine
    3. CA and B
    4. DThe amount of adenine and guanine = the amount of thymine and cytosine
  10. 10The adjacent nucleotides are joined by
    1. AIonic bond
    2. BHydrogen bond
    3. CPhosphodiester bond
    4. DAll of these

Información

Descripción
Test sobre biochemistry , creado por Mohamed Ayman el 09/03/2017.
Idioma
English
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