DNA replication

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Author:
mgeorgi1
ID:
174412
Filename:
DNA replication
Updated:
2012-09-30 16:11:33
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Biochemistry
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Description:
Biochemistry
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  1. Fidelity means
    - The information in the DNA is accurately copied 

    - It occurs in the new DNA strand because of the specific base pairing of the incoming deoxyribonucleoside triphosphates (A«T; G «C)
  2. DNA polymerase function
    • 1- Replicates the DNA
    • 2- Polymerizes dATP, dGTP, dCTP and dTTP into DNA
  3. - The new strand is always synthesized in the......direction
    - A............ is released
    - A...........is a preexisting “starter (short) sequence to help the DNA polymerase “get going”
    - The newly synthesized strand is......... to the template strand
    • The new strand is always synthesized in the 5’ to 3’ direction
    • A Pyrophosphate (PPi) is released
    • A “primer” is a preexisting “starter (short) sequence to help the DNA polymerase “get going”
    • The newly synthesized strand is antiparallel to the template strand
  4. - Step 1 of the DNA replication process is for the DNA double helix to........ or separate over a small region
    - The DNA polymerase only uses.............as a template. 
    - In eukaryotic cells, the DNA melts at ..............along the DNA helix. Generally this occurs at regions rich in.......

    • Step 1 of the DNA replication process is for the DNA double helix to “melt” or separate over a small region
    • The DNA polymerase only uses single stranded DNA (ssDNA) as a template. 
    • In eukaryotic cells, the DNA melts at multiple sites along the DNA helix. Generally this occurs at regions rich in AT base pairs
  5. - As the two DNA strands separate, they form a “V”, This is called the ........ – it is the site where active replication occurs
    - Replication is....... – replication forks move in.........directions from the origin, generating a bigger bubble
    - There are proteins required for DNA strand separation. These proteins are required for.......
    • As the two DNA strands separate, they form a “V”
    • This is called the replication fork – it is the site where active replication occurs
    • Replication is bidirectional – replication forks move in opposite directions from the origin, generating a bigger bubble
    • There are proteins required for DNA strand separation. These proteins are required for
    • 1.) maintaining the separation of the parental
    • strands and
    • 2.) unwinding the double helix ahead
    • of the advancing fork
  6. What are the Required proteins in DNA
    • DnaA Protein – which finds AT rich regions, and uses an ATP to melt the “AT” H-bonds
    • DNA helicase – which will recognize the ssDNA near the replication fork and snatch onto it, adding energy to keep the strands apart and unwind the double helix
    • Single strand DNA-binding proteins (SSB) proteins – which serve 2 functions;
    • 1- To get in the way of hydrogen bonds reforming between bases, and one
    • 2- To cover the ssDNA sites so DNA nuclease enzymes do not degrade the ssDNAs
  7. - Synthesis of DNA is ................
    - The DNA polymerase can only “read” the parental nucleotide sequences in .........
    - Direction so that the new DNA strand is synthesized in the 
    ..................
    • - Synthesis of DNA is discontinuous
    • - The DNA polymerase can only “read” the parental nucleotide sequences in the 3’5’
    • - Direction so that the new DNA strand is synthesized in the 5’3’ direction
  8. - The leading strand is the one that is in the ...... direction for DNA polymerase.
    - This strand is synthesized ..........
    - The “lagging” strand is synthesized in short spurts called.....
    • - The leading strand is the one that is in the right direction for DNA polymerase.
    • - This strand is synthesized continuously
    • - The “lagging” strand is synthesized in short spurts Okazaki fragments

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