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GETTING TO
KNOW DNA
WHAT DO YOU ALREADY KNOW?
PART 1: KNOWING YOUR NUCLEOTIDES
 DNA is
the code
that makes you
who you are.
 The code has
ONLY 4
LETTERS!!!
 A = Adenine
 T = Thymine
 C = Cytosine
 G = Guanine
PART 1: KNOWING YOUR NUCLEOTIDES
A, T, C, & G
are nucleotides.
 Nucleotides:
The building
blocks of DNA
that match up to
form the double
helix shape
 A + T bond
 C + G bond

PART 1: KNOWING YOUR NUCLEOTIDES
Nucleotides all have the
same general structure.
1. Phosphate Group
is the backbone
2. Sugar is the link
3. Nitrogen Base is
the code: A, T, C, G
 The green base can
change, but yellow and
pink stay the same

PART 1: KNOWING YOUR NUCLEOTIDES
 DNA is the code to
make RNA.
 RNA is the code to
make proteins!
 RNA replaces the
deoxyribose sugar link
of DNA with just a
ribose sugar link
 RNA also replaces the
T nucleotide for a U
 U = Uracil
 A + U bonds
DNA HISTORY: ERWIN CHARGAFF (1950)
Erwin did the
experiments to
prove that A
matches with T
and that C
matches with G
in a 1 to 1 ratio.

DNA HISTORY:
ROSALIND FRANKLIN (1951)
Rosalind took
the first clear
photo of DNA

DNA HISTORY: MARTHA CHASE &
ALFRED HERSHEY (1952)
First to
absolutely
prove that
DNA is the
molecule that
is the code
for all genes

CURRENT APPLICATION: (JUST FOR FUN)
DNA HISTORY: FRANCIS CRICK &
JAMES WATSON (1953)
 Determined
the “doublehelix” shape
of DNA from
Rosalind’s
photo.
 Some say
Rosalind got
it first!
CHECK FOR UNDERSTANDING
1.
2.
3.
4.
5.
6.
What is a NUCLEOTIDE?
What are the 3 parts of a nucleotide?
Which nucleotide bonds with “A”?
Which nucleotide bonds with “C”?
Which nucleotide is replaced with
“U” for RNA?
Which nucleotide bonds with “U”?
PART 2: DNA REPLICATION
We need to pass on
our genes to new
cells (by Mitosis)
and to our offspring
(by Meiosis).
 DNA Replication is
the process by which
perfect copies of our
DNA are made!

PART 2: DNA REPLICATION
Think of DNA as a zipper, two sides that are
held together by matching base pairs.
 The enzyme helicase unwinds the helix and
forces the zipper to open!

The Chainsaw!!!
PART 2: DNA REPLICATION

Opening the DNA
causes “bubbles” to
form
 Replication
can
only happen when
these single strands
of DNA are
exposed!
PART 2: DNA REPLICATION

Replication is
“semi-conservative”
because the original
(parent) strands stay
the same, while new
matching (daughter)
strands are added on.
PART 2: DNA REPLICATION
The nucleus is
filled with a pool of
extra nucleotides,
waiting to make
new DNA.
 DNA Polymerase
is like a train that
rides along the rail
of DNA and
attaches matching
base pairs.

CHECK FOR UNDERSTANDING
1.
2.
3.
Why do the DNA strands need to be “unzipped”
before they can be copied?
What is “semi-conservative” DNA replication?
In replication, parents strands are matched with
new nucleotides to make a _________ strand.
CHECK
FOR
UNDERSTANDING
FIND THE MATCH!
C
G
A
T
PART 3: PROTEIN SYNTHESIS
Transcription:
A process
where a section
of DNA code is
copied into its
matching RNA
code.
 Makes
“messenger”
mRNA

PART 3: PROTEIN SYNTHESIS

mRNA leaves the nucleus to find a ribosome
in the cytoplasm.
PART 3: PROTEIN SYNTHESIS
Translation: The
process of decoding
the mRNA code
 Every 3 letter code
of mRNA (codon) =
amino acid
 Transfer RNA bring
amino acids to match
the codes of mRNA
 Amino acids build
the protein

PART 3: PROTEIN SYNTHESIS

mRNA codes
for 20
different
amino acids
that have
almost infinite
combinations
for making
needed
proteins.
AAA
F
CAA
V
GAA
L
UAA
I
AAC
L
CAC
V
GAC
L
UAC
M
AAG
F
CAG
V
GAG
L
UAG
I
AAU
L
CAU
V
GAU
L
UAU
I
ACA
C
CCA
G
GCA
R
UCA
S
ACC
W
CCC
G
GCC
R
UCC
R
ACG
C
CCG
G
GCG
R
UCG
S
ACU
-
CCU
G
GCU
R
UCU
R
AGA
S
CGA
A
GGA
P
UGA
T
AGC
S
CGC
A
GGC
P
UGC
T
AGG
S
CGG
A
GGG
P
UGG
T
AGU
S
CGU
A
GGU
P
UGU
T
AUA
Y
CUA
D
GUA
H
UUA
N
AUC
-
CUC
E
GUC
Q
UUC
K
AUG
Y
CUG
D
GUG
H
UUG
N
AUU
-
CUU
E
GUU
Q
UUU
K
COMPARING TO BUILDING A BUILDING
Architect's Office =
Nucleus
 The Master Plan by
the architect = DNA
 The location of the
land to build the
building = cytoplasm
 The Blue Prints that
communicate the
Master Plan = mRNA

COMPARING TO BUILDING A BUILDING
The Supervisor at the
site of construction =
Ribosome
 The concrete and
lumber to build the
building = amino acids
 The trucks to bring the
lumber = tRNA
 The finished building =
Complete Protein

CHECK FOR UNDERSTANDING
Now let’s compare
building a protein to
making a song.
 The completed song =
the completed protein
1. What is the recording
studio?
2. What is the tape player?
3. What are the musical
notes?
