Inquiry: How is DNA used to
store and transmit cell
information?
Essential Question #1:
Compare the structures of DNA and RNA.
Essential Question #2:
Compare the functions of DNA and RNA.
Relationship Between Chromosomes and Cell
DNA
• Double helix (twisted
ladder)
• Bases joined by hydrogen
bonds (A-T and C-G)
–
–
–
–
A=Adenine
T=Thymine
C=Cytosine
G=Guanine
(Bases spell a code for life)
• Composed of Nucleotides
Nucleotide = deoxyribose sugar, phosphate, & base
What does DNA do?
• Contains recipe for making proteins
• Gives us our inherited characteristics
– Replication - DNA copies itself exactly for
cell division
DNA Models
1. Color the DNA nucleotides
• Use the color codes below
– Cytosine – green
– Guanine – blue
– Adenine – red
– Thymine – purple
– Sugar – white
– Phosphate – yellow
2. Cut out the DNA nucleotides
• Just like assembling a puzzle, put the nucleotides
together randomly to create DNA. Words will be upside
down on one side.
3. Tape it together but DO NOT TAPE ACROSS THE
BASES (ACTG) in the middle
DNA Replication
• DNA is unique among all known molecules
because it is the only one that is capable of
duplicating itself.
• The process of duplication is called replication.
• During replication, the two complementary
strands which form the DNA molecule unzip and
then are used as templates from which new
strands are made as free nucleotides combine
with their complementary bases.
• The result is one side of each new DNA strand is
"old" and the other side is "new".
Why does this happen?
Enzymes that make DNA
Replication possible
• Helicase – helps unzip the DNA molecule
by breaking the hydrogen bonds between
base pairs
• DNA Polymerase – reconnects the free
nucleotides with the original DNA strand
How DNA Replication Works
Animation
DNA Replication Models
•
Using your DNA model that you and your partner(s)
constructed, cut the last 3 DNA bases where the
hydrogen bonds exist.
•
Slightly pull your newly separated sections of DNA
apart. Determine which bases will be able to reattach
to the last 3 nucleotide bases. Fill in the diagram
below.
• Color and cut out the new complementary
free nucleotides.
• Attach the new complementary free
nucleotides to your DNA models to show
how replication will occur. Use the figure
below as a hint.
Summary of DNA Replication
• DNA is unzipped or unwinds.
• The unwinding of the helix is facilitated by an
enzyme called helicase
• Complementary bases from free nucleotides are
paired up with their match.
• DNA polymerase is another enzyme that
reconnects the bases of the two new DNA
strands
• DNA replication occurs to create a copy of DNA
before cell reproduction.
Describe what is
happening in the
picture?
What is this process
called?
http://present.smith.udel.edu/biotec
h/rDNA.html
SB2. Students will analyze how biological
traits are passed on to successive
generations.
a. Distinguish between DNA and RNA.
Comparing/Contrasting DNA/RNA
1. The sugar in the RNA molecule is ribose. DNA's sugar
is deoxyribose.
2. RNA is usually a single stranded molecule while DNA
is nearly always double stranded.
3. DNA's rigid double helix structure allows for only one
function (information storage) whereas RNA's greater
molecular diversity results in a wider range of
functions
4. RNA uses the nucleotide uracil instead of thymine
5. DNA is larger than RNA
6. RNA is much less stable than DNA. As a single
stranded molecule it has no way of repairing itself
Use a Venn
chart to
compare
DNA and
RNA
What is Transcription?
• Making a copy of the information in DNA
as a new version called RNA
• When transcription is finished, the portion
of the DNA that coded for a protein, i.e. a
gene, is now represented by a messenger
RNA molecule
• This mRNA can be used as a template for
translation later.
How Transcription Works
• DNA unzips and RNA polymerase
(enzyme) binds to one strand of DNA
• A chain of RNA nucleotides is created as
each new RNA nucleotide complementary
to the DNA nucleotide it is hydrogen
bonded to.
• The completed mRNA molecule is
released from RNA polymerase .
Transcription Models
• With your DNA model in front of you,
demonstrate the process of transcription.
– Fold the DNA model where the base pairs
touch
– Match up the complementary pieces of the
RNA nucleotides from
• A-U
• C-G
• T-A
Transcription Models
• Color the RNA nucleotides
• Use the color codes below
– Cytosine – green
– Guanine – blue
– Adenine – red
– Uracil – light purple or pink
– Sugar – white
– Phosphate – yellow
Transcription Models
• Cut out the RNA nucleotides
• Tape these nucleotides together as a new
molecule. DO NOT ATTACH TO THE
ORIGINAL DNA MODEL.
• What process can occur next?
Modeling Review
What is Translation?
• DNA translation is the process that converts an
mRNA sequence into a string of amino acids
that form a protein.
• This fundamental process is responsible for
creating the proteins that make up most cells.
• It also marks the final step in the journey from
DNA sequence to a functional protein.
Translation
RNA Proteins
• Look at your new RNA molecule that was
created using information that was stored
and transmitted from DNA.
• Fill in the letters that represent the bases in
YOUR DNA model.
• Next, fill in the letters of the bases that are in
YOUR RNA model.
• Starting at the top of YOUR DNA model circle
every three letters as a DNA base sequence.
• Write these 3 DNA letters in the first column
of your table
Example
Starting at the top of YOUR RNA model circle
every three letters as a codon.
Write these 3 RNA letters in the first column of
your table
Example
Identify the Amino Acid with
Table 11-2
Anticodons
• Identify the tRNA anticodon from the mRNA
codon
• Fill in the anti codon in the table and in the
blanks on your tRNA cut out and label the amino
acid that it will be bring to mRNA
• Attach this tRNA cutout to YOUR RNA strand
Example
Modeling Review