DNA replication is the process where a copy of a
DNA strand is made and the genetic information
it contains is duplicated.
An enzyme known as helicase enters at a
adenine and thymine bond at a point known as
the origin of replication. Helicase unwinds the
double helix as it goes through the DNA strand.
As helicase goes through the DNA strand, single
stranded binding proteins cling to the sides of
the strand to keep them together.
Polymerase III then reads the parent strand and
synthesizes the other bases.
DNA primase places an RNA primer from 51 to
31. The enzyme polymerase I changes that RNA
primer into DNA. DNA ligase forms
phosphodiester bonds. Adenine and thymine
form a double bond and cytosine and guanine
form a triple bond. When one of the purine
bases bonds with a pyrimidine base, they form a
quintuple (5) bond.
After DNA replication takes place, you are left
with two identical DNA strands.
Replication occurs so that the genetic material
can be passed from the original cell to the
daughter cell. This leads to the transfer of traits.
DNA Replication occurs in interphase.
Interphase is the period between the division of
two cells. During interphase, the cell increases in
size and makes a copy of the cells’ DNA to
prepare for the next division.
What are mutations?
A mutation is a permanent change in the DNA
sequence that makes up genes. They differ in
size from one DNA base to a large segment of
How do we get them?
Mutations can be inherited from a parent. In
these cases, they are referred to as hereditary
mutations. Once acquired, they are permanent
throughout that person’s lifetime.
When a mispairing of bases occurs because of a
shifting in the position of the nucleotides, it is
called a wobble, one of a few different ways to
form a mutation.
Insertions or Deletions
When a nucleotide is inserted or deleted at the
wrong time or place, it creates another
mutation. This process is known as strand
slippage. A newly synthesized strand slightly
loops out, which causes an addition of an extra
nucleotide base. Sometimes, the template
strand becomes slightly misplaced. This results
in the deletion of nucleotide bases in the newly
• A compound structure at the end of an
• Keep the ends of different chromosomes in
the cell from attaching to each other
Short, newly synthesized DNA fragments that
are formed on the lagging template strand
during DNA replication.
• A specific type of enzyme that facilitates the
joining of DNA strands together by catalyzing
the formation of a phosphodiester bond
• Seals breaks in the phosphate-sugar backbone
• Disease caused by an uncontrolled division of
abnormal cells in a part of the body
• Telomerase causes cancer cells to divide and
• A ribonucleoprotein
• Adds telomere sequence to the 31 end of DNA
• DNA polymerase then completes the synthesis
of the uncompleted ends of the other strand