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23 Cards in this Set
- Front
- Back
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What is a replication fork?
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The area where the replication of DNA will actually take place |
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Where does DNA replication begin?
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DNA replication starts at origins of replication, which are sequences in the DNA that are recognized by replication proteins |
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What is a consensus sequence?
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A sequence of DNA having similar structure and function in different organisms |
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The function of helicase: |
to unwind the DNA forming a structure called the replication fork |
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In what direction does DNA replication proceed?
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DNA replication goes in the 5' to 3' direction because DNApolymerase acts on the 3'-OH of the existing strand for adding free nucleotides |
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The function of single strand binding proteins:
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Binds to single-stranded DNA and prevent it from re-forming a double stranded structure |
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The function of topoisomerase:
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Relax supercoiling |
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The function of DNA polymerase |
synthesizes DNA molecules from deoxyribonucleotides, the building blocks of DNA |
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What is the leading and lagging strand?
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Leading strand: The strand that is being replicated continuously in the 5' to 3' direction Lagging strand: The strand that is being replicated in fragments in the 5' to 3' direction because it needs to be flipped to be read in the correct direction |
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What are Okazaki fragments?
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short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication |
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Why are primers necessary? |
It serves as a starting point for DNA synthesis. It is required for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA. |
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DNA Replication process |
"unzipping" of the parent molecule as the hydrogen bonds between the base pairs are broken. Once exposed, the sequence of bases on each of the separated strands serves as a template to guide the insertion of a complementary set of bases on the strand being synthesized. |
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Why is DNA replication of linear chromosomes a problem? |
there's no way to get the fragment started because the primer would fall beyond the chromosome end |
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How to replicate linear chromosomes? |
look into textbook |
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Why are telomeres/telomerase considered a “double-edged sword”? |
look in textbook |
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What are the main causes of mutations/DNAdamage?body? |
Oxidative DNA damage refers to the oxidation of specific bases Hydrolytic DNA damage involves deamination or the total removal of individual bases. Ultraviolet and other types of radiation can damage DNA in the form of DNA strand breaks. This involves a cut in one or both DNA strands |
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Base analouges: |
resemble nitrogen bases |
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Base modifying agents: |
react chemically with DNA bases to cause a mutation. |
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Intercalating agents: |
Insert themselves in between the bases causing a disruption the DNA sequence |
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What specific DNA alteration is caused by UV light? |
pyrimidine dimer formation—covalentbonds between adjacent pyrimidine bases |
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Base excision repair: |
Corrects damage to a single base |
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Nucleotide excision repair: |
Repairs major distortions in the doublehelix |
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Mismatch repair: |
1.MutS recognizes mismatched bases 2.MutH recognizes methylated parent strand and nicks in the daughter strand 3.New strand is removed and replaced between the nick and the mismatch |
