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Intro to DNA Video
DNA Structure
Notes
Chapter 12-1 Pgs 291-294
Student Expectation (SE) 6A – identify components of DNA and describe
how information for specifying the traits of an organism is carried in the
DNA
• Where does your DNA come from?
• What are the parts of DNA?
• What are the parts of a nucleotide?
1. Nuceic Acids
Function?
• Nucleic acids like
DNA and RNA store
and transmit
hereditary
information for
coding for proteins.
2. DNA Structure
• DNA is a macromolecule
made up of repeating
monomers called
nucleotides and is
shaped like a double
helix.
• Nucleotide:
1.
Phosphate
2.
5-carbon sugar
(deoxyribose)
3.
Nitrogenous
base
DNA Nucleotide Monomer
Phosphate
Group
O
O=P-O
O
Nitrogenous base
(A, G, C, or T)
5
CH2
O
N
C1
C4
C3
C2
Sugar
(deoxyribose)
Review
• What is the monomer of a nucleic acid?
– A. Amino Acid
– B. Glucose
– C. Nucleotide
– D. Phosphate
What are the parts of a
nucleotide?
4. Chargaff’s Rule
• Adenine must pair with Thymine
• Guanine must pair with Cytosine
• Their amounts in a given DNA molecule will be about
the same percentages.
T
A
G
C
DNA Double Helix
5
O
3
3
O
P
5
O
C
G
1
P
5
3
2
4
4
2
3
1
P
T
5
A
P
3
O
O
P
5
O
3
5
P
• DNA is like a twisted ladder
• What part of DNA is like the
rung on the ladder?
• What part of DNA is like the
outsides of the ladder?
DNA Double Helix
“Rungs of ladder”
Nitrogenous
Base (A,T,G or C)
“Legs of ladder”
Phosphate &
Sugar Backbone
Question of the Day:
• If there is 30% Adenine, how much
Cytosine is present?
Answer:
• There would be 20% Cytosine.
Adenine (30%) = Thymine (30%)
Guanine (20%) = Cytosine (20%)
(50%) = (50%)
5. How does DNA
differ between
species?
• ALL living organisms
use the same four
bases (A, T, G, C) to
code for proteins.
• It is the order of the
code that is different
between living things!
Use your body to represent a
nucleotide structure
Sugar
Base
Phosphate
1. Decide what
Nitrogenous base your
right arm will
represent
2. Find someone on the
other side of the room
who is your
“complementary base”
Now lets create an antiparallel DNA molecule!
•Find a complementary base that
would bind to your base and
connect your hands together with
Hydrogen Bonds.
•Now create a DNA molecule by
creating “covalent bonds” by
linking elbows with another
someone else’s “phosphate”
elbow
Draw and Describe DNA
Structure
• Include in your description:
– The parts of DNA
– The Parts of a Nucleotide
– What part of the nucleotide determines genes
– How DNA differs between different organisms
• Include in your drawing
– A nucleotide
– All four nitrogenous bases
– Labels