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32 Cards in this Set

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  • Back
109) What are the three types of mutations you can have?
(PDT) Point Mutations, Deletions and duplications, Tranlocations.
110) What type of mutations is DNA repair normally limited to?
Point Mutations.
111) What types of mutations have the potential to ruin the whole protein?
Point Mutations.
112) What are some types of Point Mutations?
Transitions, Transversions, Nonsense
113) What are Transition mutations?
(C<>T, A<>G).
114) What are Transversion mutations?
115) What is a Nonsense Mutation?
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.
116) What is a Silent Mutation?
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.
117) What is a Missense Mutation?
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).
118) What is a Frameshift Mutation (severe)?
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.
119) The insertion or deletion of anything but __bp will bring on a different reading frame?
3 base pairs.
120) What are two causes of Spontaneous Point Mutations?
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.
121) What is the name of the 3 enzymes used in Post Replication Mismatch Repair?
Endonucleases, DNA polymerase, DNA ligase.
122) What do endonucleases do?
Endonucleases are enzymes that cleave the phosphodiester bond within a nucleutide chain.
123) What do exonucleases do?
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.
124) Methyl groups in the form of 5’-methyl-cytosine are found in what nucleotides sites?
CG sites [---------C(m)—G--------------] or [-----------G—C(m)-----------], the methyl group is attached to the cytosine nucleotide.
125) What would you call the above cytosine nucleotide together with the methyl group?
126) High levels of methyl groups are found in areas that are?
Inactivated, including gene promoters and heterochromatin.
127) Mutagens are more dangerous if they hit DNA during what phase?
Synthesis (S-phase).
128) What are some external mutagens?
Sunlight (UV rays), X-rays, Chemicals (ex. Cigarette smoke, Nitrite etc.).
129) UV rays, drive up what unfavorable reaction forward, thus, causing a mutation?
Thymine Dimers.
130) What is another name for Thymine Dimers?
Pyrimidine Dimers.
131) What are the 2 main repair mechanisms?
Base Excision Repair (used for single base problems, since it only cuts one base), and Nucleotide Excision Repair (for bulkier DNA segments).
132) For a Thymine Dimer repair, what method would be most adequate?
TT-dimer repair.
133) What is the success rate of Repair Reactions?
134) Which type of repair mechanism is more sloppy, Repair DNA polymerases or Replication DNA polymerases?
Repair DNA polymerases are sloppier.
135) Is there a post-replication repair after a Repair DNA polymerase?
136) What is Cocayne Syndrome?
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.
137) What is Xeroderma Pigmentosum (XP)?
It’s a defect of genome-wide nucleotide excision repair. Sunburn, skin cancer 2000% risk, 30 year reduced life expectancy, autosomal recessive.
138) XP is present only if how many copies of a XP gene is mutated?
2 (recessive).
139) What does complementation mean?
That cell 1 provides a protein cell 2 needs or vice versa.
140) What type of cancer is caused by a defect in post-replication mismatch repair?
Non-polyposis colon cancer.