Characteristics of DNA
and
The Process of DNA Replication
NEXT
DNA Characteristics
(deoxyribonucleic acid)
BACK
NEXT
DNA Characteristics
(deoxyribonucleic acid)
Macromolecule consisting of smaller
subunits called nucleotides
BACK
NEXT
DNA Characteristics
(deoxyribonucleic acid)
Macromolecule consisting of smaller
subunits called nucleotides
• Two chains of nucleotides are joined by
their nitrogen bases through hydrogen
bonds
BACK
NEXT
DNA Characteristics
(deoxyribonucleic acid)
Macromolecule consisting of smaller
sub units called nucleotides
• Two chains of nucleotides are joined by their
nitrogen bases through hydrogen bonds
• Nucleotides bond according to Chargaff’s
Rules
– Adenine always bonds with thymine (A-T)
– Guanine always bonds with cytosine (G-C)
BACK
NEXT
DNA Characteristics
(deoxyribonucleic acid)
Macromolecule consisting of smaller
sub units called nucleotides
• Two chains of nucleotides are joined by their
nitrogen bases through hydrogen bonds
• Nucleotides bond according to Chargaff’s
Rules
– Adenine always bonds with thymine (A-T)
– Guanine always bonds with cytosine (G-C)
• The DNA strand is twisted to form a double
helix
BACK
NEXT
DNA Characteristics
(deoxyribonucleic acid)
•
•
•
•
Macromolecule consisting of smaller
sub units called nucleotides
Two chains of nucleotides are joined by their
nitrogen bases through hydrogen bonds
Nucleotides bond according to Chargaff’s
Rules
– Adenine always bonds with thymine (A-T)
– Guanine always bonds with cytosine (G-C)
The DNA strand is twisted to form a double
helix
Each organism has its own unique DNA
BACK
NEXT
sequence
Nucleotides
• Nucleotides have 3 parts
– A phosphate group
– A 5 carbon sugar called
deoxyribose
– A nitrogen containing base
• There are four types of
nitrogen containing bases
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A A
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A A T
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A A T G
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A A T G T
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A A T G T A
A C G T
BACK
Knowing that A bonds with T
and G bonds with C, complete
the second DNA strand.
• Click on the letter that will complete the
strand
A G C T G A T T A C A T C
T C G A C T A A T G T A G
A C G T
BACK
DNA with Hydrogen Bonds
BACK
Erwin Chargaff
• Erwin Chargaff determined experimentally
that the amount of adenine (A) equaled
the amount of thymine (T) and the amount
of guanine (G) equaled the amount of
cytosine (C) in a DNA strand
• This concept is known as Chargaff’s Rules
APPLY THIS CONCEPT
BACK
The double helix structure
of DNA was determined by
James Watson and Francis
Crick in 1953.
Rosalind Franklin and Maurice
Wilkins contributed to their
discovery by providing
information about the atomic
structure of DNA.
BACK
The Four Nitrogen Containing
Bases
•
PURINES
•
PYRIMIDINES
Adenine
Thymine
Guanine
Cytosine
BACK
Applying Chargaff’s Rule
• A DNA strand is 15% adenine.
What is the percentage of
thymine?
ANSWER
BACK
Applying Chargaff’s Rule
• A DNA strand is 15% adenine. What
is the percentage of thymine?
THYMINE = 15%
• What is the percentage of guanine?
ANSWER
BACK
Applying Chargaff’s Rule
• A DNA strand is 15% adenine. What
is the percentage of thymine?
THYMINE = 15%
• What is the percentage of guanine?
GUANINE = 35%
• What is the percentage of cytosine?
ANSWER
BACK
Applying Chargaff’s Rule
• A DNA strand is 15% adenine. What
is the percentage of thymine?
THYMINE = 15%
• What is the percentage of guanine?
GUANINE = 35%
• What is the percentage of cytosine?
CYTOSINE = 35%
TRY ANOTHER
BACK
Applying Chargaff’s Rule
• A DNA strand has 500 nucleotides, 135 of
which are cytosine. How many adenine
are in the strand?
ANSWER
BACK
Applying Chargaff’s Rule
• A DNA strand has 500 nucleotides, 135 of
which are cytosine. How many adenine
are in the strand?
A = 115
• How many guanine are in the strand?
ANSWER
BACK
Applying Chargaff’s Rule
• A DNA strand has 500 nucleotides, 135 of
which are cytosine. How many adenine
are in the strand?
A = 115
• How many guanine are in the strand?
G = 135
• How many thymine are in the strand?
ANSWER
BACK
Applying Chargaff’s Rule
• A DNA strand has 500 nucleotides, 135 of
which are cytosine. How many adenine
are in the strand?
A = 115
• How many guanine are in the strand?
G = 135
• How many thymine are in the strand?
T = 115
BACK
DNA Replication
The process of copying the DNA sequence
to make another copy
1. DNA helicase breaks the hydrogen bonds between
the two strands of nucleotides
2. DNA polymerase reads the original DNA strand and
synthesizes a new DNA strand from free floating
nucleotides.
-
Each side of the original DNA strand acts as a template or
pattern to make the new DNA strand
DNA synthesis can only occur in the 5’ to 3’ direction. This
results in a leading strand and a lagging strand.
BACK
NEXT
DNA Replication
• DNA Replication results in 2 DNA strands that
are identical to the original parent strand.
Watch DNA Replication
BACK
NEXT
Leading Strand
• The leading strand is the DNA strand
being synthesized in the normal 5’ to 3’
direction
BACK
Lagging Strand
• The lagging strand is the strand replicating
from the 3’ to 5’ template
• The lagging strand is replicated in small
segments because DNA strands can only
be synthesized in the 5’ to 3’ direction
• The resulting small segments of DNA
produced are called Okazaki fragments
and are spliced together by DNA ligase
BACK
Okazaki Fragments
• Okazaki Fragments are small pieces of
DNA that are synthesized during DNA
replication from the 5’ to 3’ template
• The fragments were discovered by Reiji
and Tuneko Okazaki, a husband and wife
team.
BACK
DNA Replication