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Section 7.2: DNA Structure and Replication
Why is DNA important?
• WEAK: “It is the “hereditary molecule”
• WEAK: It is the “molecule of life”
• WEAK: It “holds the blueprint for your body
• GOOD: DNA holds the code for your proteins and
determines when and how your body develops
How does your
body make
this…….
Into These…?
 So these…..
Hold the code for
these…
What is DNA and How Does It
Work
 https://www.youtube.com/watch?v=z
wibgNGe4aY
Blueprint from DNA
(Your Hair)
RNA copy of your
Human Hair
All amino
acids
Your Hair
Ribosomes
(protein
factory)
DNA Structure
1.
2.
The basic unit of DNA is the “DNA nucleotide”
A nucleotide is drawn like this:
Generic DNA Nucleotide
Base
Phosphate
Sugar
(deoxyribose)
•Cytosine
•Guanine
•Adenine
•Thymine
ADENINE Nucleotide (fill in)
Base
•Adenine
Phosphate
Sugar
(deoxyribose)
THYMINE Nucleotide (fill in)
Base
•Thymine
Phosphate
Sugar
(deoxyribose)
CYTOSINE Nucleotide (fill in)
Base
•Cytosine
Phosphate
Sugar
(deoxyribose)
GUANIN Nucleotide (fill in)
Base
•Guanine
Phosphate
Sugar
(deoxyribose)
THYMINE Nucleotide (fill in)
Base
•Thymine
Phosphate
Sugar
(deoxyribose)
Make a Single Strand of DNA
1.
2.
3.
DNA nucleotides link together to make strands
The phosphate of one nuceolotide is bonded to the
sugar of the next nucleotide
Make a strand of “GCAT”
G
G
Hard
Way !
C
C
A
A
T
T
Easy
Way!
Double Strand of DNA
 DNA usually exists in double stranded form
 “A” always pairs with “T”
 “C” always pairs with “G”
 Draw strand “ACGTACTC” and then draw it partner
strand
Color DNA Double Helix
Proteins
1.
2.
3.
4.
make up most of your weight
make up all of your organs
are the “structural molecules” of your body
are made of :
Question: How can the same ~20 amino
make up proteins with such
different
characteristics?
Answer: Your chromosomes (made of
DNA) tell your ribosomes to
put the amino acids together
in a certain way.
acids