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Bio - 13.3 Review

Terms in this set (21)

How does DNA store information?
has a string of letters in a very specific order with every organism having a different and unique sequence
Why are base pairs important in replication?
each strand of DNA contains all of the information needed to reconstruct the other half because of base pairing
Where does eukaryotic DNA replication take place? When and what does it make?
nucleus before cell division to make 2 identical copies
What happens in the first step of eukaryotic DNA replication?
the DNA is opened & unzipped in both directions, making a replication fork
Which enzyme is used in the first step of eukaryotic DNA replication? What is its job?
helicase - breaks hydrogen bonds that hold base pairs together
What is a replication fork?
a Y-shaped region where the parental strands of DNA are being unwound
What happens in the second step of eukaryotic DNA replication?
new DNA is built, making a replication bubble as helicase continues to unzip
Which enzyme is used in the second step of eukaryotic DNA replication? What is its job?
DNA polymerase - binds to open DNA by attaching new, free-floating nucleotides following Chargaff's rule
What is a replication bubble?
the part of the DNA that is open for replication
Which way is DNA being built? Why is it this way?
from 5' → 3' because it is being read from 3' → 5' and DNA runs antiparallel
What is the third step of eukaryotic DNA replication?
editing - because of the bubble, not all of the DNA can be seamlessly copied & an enzyme needs to stick fragments together
Define leading strand.
one half of the strand that is seamless or one piece in building because it is being read from 3' → 5' following the direction of helicase
Define lagging strand.
one half of the strand that is copied piece by piece because it is being read from 3' → 5' following the direction of the origin
What are Okazaki fragments?
small pieces of DNA all side-by-side created by lagging strands
What is the enzyme used in the third step of eukaryotic DNA replication? What is its job?
ligase - sticks Okazaki fragments together by using phosphodiester bonds
Where does replication begin on the DNA molecule?
at hundreds of places at once and proceeds in both directions until all DNA is copied
What does DNA look like in a prokaryotic cell?
single, circular strand that is smaller than eukaryotes
Where does DNA replication take place in a prokaryotic cell?
cytoplasm
How does DNA replication work in a prokaryotic cell?
replication begins at one point proceeding in 2 directions until all of it is copied (simple & fast!)
Before a cell divides, it duplicates its DNA in a process called...
replication
The DNA that results from replication consists of...
a) One molecule with two new strands
b) Two molecules that each contain one new and one original strand
c) Two molecules composed of new strands
d) Two molecules composed of old strands
b) Two molecules that each contain one new and one original strand

(called semi-conservative)
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