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DNA Replication AP Biology
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Regents Biology DNA Replication…
THE PROCESS IS _________________ Meaning… _______________________
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Origins of Replication
Definition: ________________________
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Where does the energy originate to fuel this reaction?
ANSWER: ________________________
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Antiparallel Arrangement of DNA
What is meant by antiparallel?? _______________
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DNA Replication
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Steps to DNA Replication
DNA unwinds using __________ and opens at _________________________________ _______ ________ is added to a strand by ___________ so DNA polymerase can attach. At the ________ __________DNA polymerase attaches and adds ________________________ The other strand called ______________ grows also in ______________________ but in ____________________________ A DNA molecule replaces the primer and ___________ glues the segments together
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The DNA can repair itself!
DNA Polymerase proofreads first. Mismatch Repair: Sometimes nucleotides are missed and the cell uses special enzymes to fix incorrectly paired bases. Nucleotide Excision Repair: A nuclease cuts out the damage DNA and the gap is filled with the right nucleotides. How can DNA be damaged? What is a “thymine dimer”?
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What is the purpose of a telemere?
THE PROBLEM: DNA can only be added to 3’ end – how to finish at 5’? Gaps are left and ends become shorter each time THE SOLUTION: Telemeres do not contain genes but repeated nucleotide sequences (TTAGGG). As a result, as the chromosomes shortens only the repeated units shorten (telemere) rather than the genes!!!
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What happens if the chromosomes gets too short ?
Telomerase helps restore the ENDS!!
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