Download DNA Structure and Replication

DNA Structure and Replication
Cell
Nucleus
Chromosomes
DNA
Biology 1-2
Essential Questions/Objectives
• What is DNA?
• How does it copy itself before
cells divide?
• Explain the structure of DNA.
James Watson and Francis Crick:
Discovered
the structure
of DNA in
1953.
Discussed
probable
mode of
replication.
DNA Replication
Complementary Strands Separate
Parent Strands Serve as Template
Nucleotides connected
DNA Song
We Love DNA
Made of Nucleotides
Phosphate, Sugar and a Base
Bonded Down One Side
Adenine and Thymine
Make a Lovely Pair
Cytosine Without Guanine
Would Feel Very Bare
What’s a Nucleotide?
Phosphate
Base
Sugar
DNA includes 4 nitrogenous bases:
Adenine pairs
with Thymine
Guanine pairs
with Cytosine
DNA is double stranded:
Hydrogen bond connects
Double Helix
the base pairs.
D = Deoxyribose
Pentose
Sugar:
5 sides
Deoxyribose Nucleic Acid (DNA)
Phosphate Group
Adenine
Thymine
P
A
Nitrogenous Base
Nucleotide
deoxyribose
Pentose Sugar
Phosphodiester
Bond
Hydrogen Bonds
P
C
Guanine
G
Cytosine
DNA Model
P
P
S
C
S
T
T
A
S
S
P
P
G
P
P
S
P
A
P
DNA Components
Backbone components:
Sugar (deoxyribose)
Phosphate group
Bases: Adenine, Thymine, Cytosine, Guanine
Base Pairs:
• Adenine and Thymine always pair up with 2
hydrogen bonds.
• Cytosine and Guanine always pair up with 3
hydrogen bonds.
DNA Structure Quiz
• Use the key on the right to
construct a model of DNA
showing 4 base pair matches.
On the finished model circle and
label one nucleotide and show
where hydrogen bonds are
located.
• Also, in writing or with a
drawing show how your model
of DNA would replicate and
what the finished product of one
replication would be.
= sugar (deoxyribose)
= phosphate
= adenine
= cytosine
= guanine
= thymine