getting to know dna:
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GETTING TO KNOW DNA:
Below is one of the molecules that makes up DNA. What functional groups do you see in the
molecule:
25%
25%
25%
25% 1. Hydroxyl2. Carboxyl3. Amine4. Phosphate
Which of the following contains the most variety of essential elements
0%
100%
0%
0%A
C
B
D
1. A 2. B3. C4. D
As you may already know, DNA stands for….
DEOXYRIBONUCLEIC ACID
Functions of DNA
• Control the processes of heredity by which cells and organisms reproduce proteins
Types of Nucleic Acids
1. DNA (deoxyribonucleic acid): double-stranded
2. RNA (ribonucleic acid): single-stranded
Nucleic Acid Structure
• The monomer units of DNA are known as nucleotides
• All nucleotides have three “parts” in common: a. Phosphateb. Pentose sugar
a. (ribose or deoxyribose)c. Nitrogen base
Deoxyribose Sugar (DNA)
• Has 5 carbons• Carbon atoms are numbered 1', 2', 3', 4',
and 5' • 5'-carbons link to the phosphate groups• 3'-carbons link to the hydroxyl groups
• Notice what’s attached to the 5’ end
And the 3’end
Is DNA a monomer or polymer
79%
21% 1. Monomer2. Polymer
What does it mean to be a polymer???
What does it mean to be a monomer?
What type of reaction is being shown below?
Covalen
t
Oxid
ation
Hydrolys
is
Dehyd
ration Syn
thesis
Polymeri
zatio
n
0%5%
0%
42%
53%
1. Covalent2. Oxidation3. Hydrolysis4. Dehydration Synthesis5. Polymerization
O
O 0
0 of 30
The molecules marked “Y” and “W”:
32%
5%
0%
5%
58% 1. Polymers and monomers2. Water and polymer3. Water and monomer4. Water and water5. Monomers and polymers
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
What two functional groups will be involved in joining nucleotides?
20%
20%
20%
20%
20% 1. Phosphate and amine2. Phosphate and hydroxide3. Amine and amine4. Phosphate and phosphate5. Amine and hydroxide
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
The monomer units of DNA are known as….
NUCLEOTIDES
All nucleotides have three “parts” in common. They all contain….
Sugar= Deoxyribose
Phosphate Group
One of FOUR different NITROGEN BASES
PLEASE UNDERSTAND, A NUCLEOTIDE IS A VERY COMPLEX STRUCTURE. IF WE REPRESENTED ALL OF THE ATOMS, IT
WOULD LOOK LIKE THIS…
Let’s Practice How to Form DNA!
We will use our hands to represent a nucleotide.
SUGAR
PHOSPHATE NITROGEN BASE
The four different Nitrogen Bases for DNA are abbreviated using the following letters….
Adenine
Thymine
Guanine
Cytosine
A
T
G
C
Using your two hands, please show how you think two nucleotides will/should bond together.
Did you put your hands like this???
Time to find out why this is wrong!!!
Adenine and Guanine are larger molecules known as…
PURINES
LOOK! TWO RINGS!!!
b. Purines: combination of a pentagon shaped ring and a hexagon shaped ring
1. Adenine2. Guanine
THYMINE and CYTOSINE are smaller molecules known as…
PYRIMIDINES
LOOK! Only one ring!!
Nitrogen Base Pairing
• Adenine and Thymine must form two hydrogen bonds to be stable while Guanine and Cytosine must form three– Makes the base pairing system an extremely
simple: the A-T and C-G pairs are the only ones physically possible
Now, when using our hands to represent the nucleotides, we must modify the nitrogen base in order to represent these PURINES and PYRIMIDINES.
How would you represent a large PURINE?
How would you represent a small PYRIMIDINE?
Full Finger
Half Finger
In DNA, a PURINE always bonds with a PYRIMIDINE when forming a “rung” of the DNA ladder.
LOOK! A long finger pairs with a short finger! In other words, a purine pairs with a pyrimidine.
In DNA, Adenine always pairs with Thymine using two hydrogen
bonds.
A T
A AND T AT THE ATOMIC LEVEL
In DNA GUANINE always pairs with CYTOSINE using three hydrogen bonds.
G C
G AND C AT THE ATOMIC LEVEL
THE
ENTIRE
MOLECULE
AT THE
ATOMIC
LEVEL
Time to use your brain and hands in order to review nucleotide structure and type.
USING YOUR HAND, SHOW ME THYMINE
USING YOUR HAND SHOW ME ADENINE
SHOW ME CYTOSINE
SHOW ME HOW CYTOSINE AND THYMINE BOND TO FORM A RUNG ON THE LADDER
THEY DON’T
OK
Now that you recognize nucleotide type and structure, it’s time to start building the polymer
from these monomers.
In order to make a molecule of DNA, you would need to create many rungs to the DNA ladder.
Look. Many Rungs.
Etc…
What part of the nucleotide alternates to form the sides of the DNA ladder?
Etc…
Sugar, Phosphate.
Sugar, Phosphate.
Sugar, Phosphate.
Etc…
What makes up the “RUNGS” of the ladder?
The Nitrogen Bases
Go Ahead!Stack you hand on top of your partners hands building two rungs of the DNA ladder.
Why is this WRONG????
The sides of the DNA ladder “run” in opposite directions. One side is actually flipped and the nucleotides are upside down!
TRY IT!!!
Because the sides of the DNA “run” in opposite directions, DNA is said to be ANTIPARALLEL.
In this DNA molecule, the THUMB part or better known as the PHOSPHATE GROUP, is said to be the 5 prime (5’) end.
5 prime
5 prime
The “hand” or sugar part of the DNA molecule makes up the 3 prime (3’) end of the DNA ladder.
3 Prime
3 Prime
• Direction of the nucleotides in one strand is opposite to their direction in the other strand: the strands are antiparallel.
• Asymmetric ends of DNA strands are called the 5′ (five prime) and 3′ (three prime) ends– 5' end having a terminal phosphate group– 3' end having a terminal hydroxyl group
If you link enough nucleotides together, the DNA molecule begins to take on the characteristic shape known as the
Double Helix
You Need…• Two Pipe cleaners• Two red twizzlers• Two black twizzlers• Many toothpicks• Four different colored marshmallows
The marshmallows represent the nitrogen bases. Let’s decide as a class what colors will represent the following nitrogen bases.
ADENINE=
THYMINE=
CYTOSINE=
GUANINE=
Cut the black twizzlers into 1.5 cm pieces.
These will represent the phosphate groups
Cut the red twizzlers into 3 cm pieces.
These will represent the sugars.
Person One
Person Two
Add the twizzlers to the pipe cleaners.
Remember, you need to alternate SUGAR (red) AND PHOSPHATE GROUPS (black).
When you are finished, your strand should not end in the same color you started with!
Did you and your partner make the same number of nucleotides
on the sides of your ladder?
If not, FIX IT!!!
Time to put together the two sides.
Using the toothpicks and marshmallows, you are to add the nitrogen bases to the sides of the ladder. Remember, the nitrogen bases “come off” the sugar part of the nucleotide. As a result, they should be coming off of the red twizzler.
Please use two of the same color marshmallows to represent one ADENINE and GUANINE. The BIG purines.Please use only one marshmallow to represent THYMINE and CYTOSINE. The small pyrimidines.
Following your teachers directions, let’s build one
long strand of DNA
A Particular strand of DNA contains 10 adenine molecules. How many thymine will
it contain:
0%
0%
0%
0% 1. 52. 103. 20 4. Not enough information
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A strand of DNA is 20% Guanine molecules. What is the percent of thymine in the strand
of DNA?
0%
0%
0%
0%
0% 1. 102. 203. 304. 405. Not enough information
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A particular strand of DNA is 40% guanine. What is the percent of adenine in the same
strand?
0%
0%
0%
0% 1. 102. 203. 304. 40
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21 22 23 24 25 26 27 28 29 30
The molecule at the location identified by the arrow:
0%
0%
0%
0%
0% 1. Adenine2. Guanine3. Sugar4. Phosphate5. thymine
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
The molecule at the location identified by the arrow:
0%
0%
0%
0%
0% 1. Adenine2. Guanine3. Sugar4. Phosphate5. thymine
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
The molecule at the location identified by the arrow:
0%
0%
0%
0%
0% 1. Adenine2. Guanine3. Sugar4. Phosphate5. thymine
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
The end of the molecule identified by the blue arrows:
0%
0% 1. Five prime2. Three prime
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21 22 23 24 25 26 27 28 29 30
The end of the molecule identified by the red arrows:
0%
0% 1. Five prime2. Three prime
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
Because the sides of the DNA ladder run in opposite directions, DNA is said to be…
0%
0%
0%
0% 1. Parallel2. Nonparallel3. Antiparallel4. proparallel
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What do you notice about all the DNA molecules in the room?
• They are all different!
If your DNA ladder contains 28 red segments of licorice, how many nucleotides
would your DNA ladder contain?
1 14 28 42 56
0% 0% 0%0%0%
1. 12. 143. 284. 425. 56
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21 22 23 24 25 26 27 28 29 30
What name is given to the reaction that was used to create this candy molecule?
Hydro
lysis
Fertiliz
ation
Dehyd
ration Syn
thesis
Cross
ing over
0% 0%0%0%
1. Hydrolysis2. Fertilization3. Dehydration
Synthesis4. Crossing over
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In the diagram below, how will these two molecules join together?
OH HO
If you were making our candy molecule in a cell where would you be found?
Cytoplas
m
Endoplas
mic Reti
culum
Golgi B
ody
Nucleus
Vacuole
0% 0% 0%0%0%
1. Cytoplasm2. Endoplasmic
Reticulum3. Golgi Body4. Nucleus5. Vacuole
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Looking around the room you noticed that a particular strand of DNA contains 20% adenine
marshmallows. What percentage of Thymine can be expected in that piece of DNA?
1% 10%
20%
40%
80%
0% 0% 0%0%0%
1. 1%2. 10%3. 20%4. 40%5. 80%
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If a DNA molecule contains 30% Guanine, then you would expect it
to have how much Adenine?
15%
20%
30%
40%
60%
0% 0% 0%0%0%
1. 15%2. 20%3. 30%4. 40%5. 60%
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What is a GENE?
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