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32 Cards in this Set
- Front
- Back
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109) What are the three types of mutations you can have?
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(PDT) Point Mutations, Deletions and duplications, Tranlocations.
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110) What type of mutations is DNA repair normally limited to?
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Point Mutations.
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111) What types of mutations have the potential to ruin the whole protein?
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Point Mutations.
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112) What are some types of Point Mutations?
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Transitions, Transversions, Nonsense
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113) What are Transition mutations?
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(C<>T, A<>G).
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114) What are Transversion mutations?
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(Purine<>Pyrimidines).
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115) What is a Nonsense Mutation?
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A nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon in the transcribed mRNA, which often leads to a nonfunctional protein.
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116) What is a Silent Mutation?
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A DNA mutation that, although they alter a particular codon, they do not alter the final amino acid, and hence do not affect the final protein.
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117) What is a Missense Mutation?
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These are a type of Point Mutations where a nucleotide is changed which results in a different amino acid. This can render the resulting protein nonfunctional (ex. Sickle-cell disease).
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118) What is a Frameshift Mutation (severe)?
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This type of mutation inserts or deletes a single nucleotide from a DNA sequence. Due to the triplet nature of gene expression, the insertion/deletion can disrupt the grouping of the codons, resulting in a completely different translation from the original.
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119) The insertion or deletion of anything but __bp will bring on a different reading frame?
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3 base pairs.
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120) What are two causes of Spontaneous Point Mutations?
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Hydrolysis reactions (of bond between purine and deoxyribose & of amino group in cytosine) and Tautomeric (This reaction results in the formal migration of a hydrogen atom accompanied by a switch of adjacent conjugated double bonds) shifts during replication.
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121) What is the name of the 3 enzymes used in Post Replication Mismatch Repair?
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Endonucleases, DNA polymerase, DNA ligase.
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122) What do endonucleases do?
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Endonucleases are enzymes that cleave the phosphodiester bond within a nucleutide chain.
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123) What do exonucleases do?
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Exonucleases are enzymes that cleave nucleotides one at a time from an end of a polynucleotide chain. These enzymes hydrolyze phosphodiester bonds from either the 3’ or 5’ terminus of polynucleotide molecules.
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124) Methyl groups in the form of 5’-methyl-cytosine are found in what nucleotides sites?
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CG sites [---------C(m)—G--------------] or [-----------G—C(m)-----------], the methyl group is attached to the cytosine nucleotide.
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125) What would you call the above cytosine nucleotide together with the methyl group?
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Methyl-cytosine.
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126) High levels of methyl groups are found in areas that are?
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Inactivated, including gene promoters and heterochromatin.
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127) Mutagens are more dangerous if they hit DNA during what phase?
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Synthesis (S-phase).
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128) What are some external mutagens?
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Sunlight (UV rays), X-rays, Chemicals (ex. Cigarette smoke, Nitrite etc.).
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129) UV rays, drive up what unfavorable reaction forward, thus, causing a mutation?
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Thymine Dimers.
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130) What is another name for Thymine Dimers?
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Pyrimidine Dimers.
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131) What are the 2 main repair mechanisms?
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Base Excision Repair (used for single base problems, since it only cuts one base), and Nucleotide Excision Repair (for bulkier DNA segments).
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132) For a Thymine Dimer repair, what method would be most adequate?
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TT-dimer repair.
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133) What is the success rate of Repair Reactions?
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99%
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134) Which type of repair mechanism is more sloppy, Repair DNA polymerases or Replication DNA polymerases?
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Repair DNA polymerases are sloppier.
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135) Is there a post-replication repair after a Repair DNA polymerase?
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No
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136) What is Cocayne Syndrome?
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It is caused by a defect of nucleotide excision repair for transcribed genes (form of dwarfism). Cockayne Syndrome (CS) is a rare form of dwarfism. It is an inherited disorder whose disgnosis depends on the presence of three signs: 1)short stature, 2) photosensitivity, 3) progeria.
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137) What is Xeroderma Pigmentosum (XP)?
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It’s a defect of genome-wide nucleotide excision repair. Sunburn, skin cancer 2000% risk, 30 year reduced life expectancy, autosomal recessive.
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138) XP is present only if how many copies of a XP gene is mutated?
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2 (recessive).
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139) What does complementation mean?
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That cell 1 provides a protein cell 2 needs or vice versa.
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140) What type of cancer is caused by a defect in post-replication mismatch repair?
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Non-polyposis colon cancer.
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