DNA replication
Warm-up
(on a fresh piece of paper to be turned in at the end of class)
1. Label the parts of this nucleotide with the
following terms: phosphate, base, sugar
2. What type of bond connects the two
strands together?
3. What would be on the other side of this
DNA?
GATTACA
DNA Replication
Whenever a cell divides into two new cells, it
needs to make an exact copy of the DNA.
The process of copying DNA is called DNA
replication.
Enzymes in DNA replication
• Enzymes are proteins that act as machines
in the cell
• 2 enzymes do the work of DNA replication:
– Helicase is responsible for separating the
2 strands of DNA
– DNA Polymerase is responsible for
adding on new Nucleotides.
We will replicate (copy) our DNA molecule in class to
produce 2 new identical DNA molecules
Helicase
• Helicase unwinds and separates the 2 strands of DNA
so that each strand may be copied.
• Helicase breaks the hydrogen bonds between the bases
of each strand.
Hydrogen
Bonds
DNA Polymerase
•
•
DNA Polymerase
adds on the
complimentary
bases to the new
strands of DNA
DNA Polymerase
makes bonds
between the
phosphate and the
deoxyribose sugar
of the nucleotides.
A
PhosphateSugar bond
T
Complementary base pairing
• If one strand of DNA has the following
sequence,
CTAATGT
GATTACA
What is the base sequence (order of
nucleotides) for the complimentary
strand?
Replication in Action
• Replication occurs simultaneously at
multiple places along a DNA strand.
– 1 chromosome is about 80 million base pairs
long.
– Replication is as fast as 50 base pairs a
second!
Animation
Your task:
On the paper you did your warm up on:
–
–
–
–
Name and period
What is the purpose of DNA replication?
What enzymes are used in replication?
Which of the following is the correct diagram?
A
B
C
When you are finished, pass your exit slip to the center aisle and work on the
green reading packet. Whatever you don’t finish is for homework.