geron_sci_255_assign_3

geron_sci_255_assign_3 - Assignment 3 1. When DNA is...

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1. When DNA is damaged by thymine dimers, a number of different DNA-repair enzymes work in conjunction to repair it. Listed below are a number of possible repair scenarios. Pick the MOST correct sequence in terms of both the order and the completeness. a. exonuclease cuts out the damaged DNA section from one strand, DNA polymerase adds the correct nucleotides to fill the gap, and DNA ligase seals the single stranded gap b. endonuclease cuts out the damaged DNA section from one strand, DNA polymerase adds the correct nucleotides to fill in the gap, and DNA ligase seals the single stranded gap c. endonuclease cuts out the damaged DNA section from both strands, DNA polymerase adds the correct nucleotides to fill in the gap, and exonuclease seals the single stranded gaps. d. Endonuclease cuts out the damaged DNA section from one strand, RNA polymerase adds the correct nucleotides to fill in the gap, and DNA ligase seals the single stranded gap e. None of the above sequences are correct. 2. Werner Syndrome: a. results in a premature death from severe atherosclerosis and congestive heart failure. b. Usually manifests itself by the age of 7 c. Is an adult progeria, which does not manifest itself till the age of 15-20 d. Results in premature death from dementia e. Is characterized by a high incidence of skin cancer 3. Xeroderma pigmentosum is a disease that is caused by: a. an infectious agent b. defective DNA repair mechanisms c. defective DNA replication mechanisms d. exposure to ionizing radiation e. Both B and D 4. Somatic mutations are always: a. heritable b. lethal c. carcinogenic d. all of the above e. none of the above
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This note was uploaded on 07/09/2011 for the course SCIENCE SCI 255 taught by Professor Cheryl during the Spring '11 term at Waterloo.

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geron_sci_255_assign_3 - Assignment 3 1. When DNA is...

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