Transcript Nucleic Acid Structure DNA Replication Structure of DNA and RNA Duplication of DNA

Nucleic Acid Structure
DNA Replication
Structure of DNA and RNA
Duplication of DNA
Information Flow From DNA
replication
(S phase)
DNA
transcription
RNA
translation
Protein
(G1 and G2
phases)
Macromolecules: Polymers
Made of Repeating Monomers
Macromolecule Monomer Unit
Carbohydrates
Sugars
Lipids
Proteins
Fatty acids
Nucleic Acids
Nucleotides
Amino acids
DNA and RNA Structure
DNA
RNA
Primary
Structure
Chain of
nucleotides
Chain of
nucleotides
Secondary
Structure
Double helix Single
folded chain
Three Parts of Nucleotide Structure
NH2
Phosphate Group
OH
HO
P
O
HC
O
N C
C
N
CH
C
N
CH2 O
N
Deoxyribose
Nitrogenous
H or H
Base
(1
of
5)
Ribose
H
H
OH
H
5-Carbon Sugar
DNA and RNA Structure
DNA
Purine
bases
Pyrimidine
bases
5-carbon sugar
Adenine (A)
Guanine (G)
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Cytosine (C)
Uracil
(U)
deoxyribose
ribose
OH
Phosphate
RNA
PO4
H
OH
PO4
OH
Clarification Pause
Turn to a partner and identify the
differences between DNA and RNA
structure
Nucleotide Chain
Nucleotides are joined
together by dehydration
synthesis
The phosphate of one
nucleotide is joined to
sugar of next
nucleotide, forming a
“sugar-phosphate
backbone”
DNA Structure
•Two nucleotide
chains
•In opposite
orientations
•Held together
by hydrogen
bonds
•Twisted into a
helix
Chemical Bonding
Covalent
Bond
Strong
Atoms
Formation of
Share
Nucleotides
Electrons and Chains
Hydrogen
Bond
Weak
Atoms
Pairing of
“Share” a Nucleotide
Hydrogen Bases in
Opposite
Chains
T
C
A
G
DNA Secondary Structure
The Double Helix
• Two polynucleotide chains are
wound together
• Bases are located inside the helix
• Sugar-phosphate groups are on
the outside as a “backbone”
• Bases are arranged like rungs on
a ladder, perpendicular to the
“backbone”
• 10 base pairs per turn of the helix
DNA Secondary Structure
The Double Helix
5’
3’
• Hydrogen bonding between
bases holds the chains
together
Base pairing rules:
A pairs with T
G pairs with C
• Polynucleotide chains have
opposite polarity
One is 5’  3’
Other is 3’  5’
3’
5’
Applying Your Knowledge
In the DNA double helix, which base is
paired with adenine?
1. Adenine
2. Cytosine
3. Guanine
4. Thymine
5. Uracil
DNA Replication
DNA Replication
DNA replication is semiconservative.
Each strand is used as a template to
produce a new strand.
AGCTAGCTAGCT
TCGATCGATCGA
AGCTAGCTAGCT  AGCTAGCTAGCT
TCGATCGATCGA
old
new
AGCTAGCTAGCT
 TCGATCGATCGA
new
old
TCGATCGATCGA
DNA Replication
DNA replication requires
1. Enzymes, including DNA polymerase
that adds nucleotides in a 5’3’ direction.
2. nucleotides
3. energy
5’—A G C T — 3’
3’— T C G A — 5’
5’— A G C T— 3’
3’—T C G A — 5’
Outcome of DNA Replication
Applying Your Knowledge
1.
2.
3.
4.
Two new chains
Two old chains
One old and one new chain
One helix has two new chains
and one has two old chains
5. None of these is correct.
After DNA replication, what is the composition
of the new double-helical molecules?