DNA Built a Special Way
By Donda Hickman
Learning Objective:
Students will understand the components of
deoxyribonucleic acid and structure of DNA.
Students will use the model they contruct as
the basis for coding for amino acids.
This information is quoted from a web site
http://www.mydna.com/genes/genetics/genetics101/genetics_dnage
ne.html
DNA, or deoxyribonucleic acid, is the hereditary material in humans and
almost all other organisms. Nearly every cell in a person's body has the
same DNA. Most DNA is located in the cell nucleus (where it is called
nuclear DNA), but a small amount of DNA can also be found in the
mitochondria (where it is called mitochondrial DNA or mtDNA).
The information in DNA is stored as a code made up of four chemical
bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human
DNA consists of about 3 billion bases, and more than 99 percent of those
bases are the same in all people. The order, or sequence, of these bases
determines the information available for building and maintaining an
organism, similar to the way in which letters of the alphabet appear in a
certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with G, to form units
called base pairs. Each base is also attached to a sugar molecule and a
phosphate molecule. Together, a base, sugar, and phosphate are called a
nucleotide. Nucleotides are arranged in two long strands that form a spiral
called a double helix. The structure of the double helix is somewhat like a
ladder, with the base pairs forming the ladder's rungs and the sugar and
phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of
itself. Each strand of DNA in the double helix can serve as a pattern for
duplicating the sequence of bases. This is critical when cells divide
because each new cell needs to have an exact copy of the DNA present in
the old cell.
State Science Standards Addressed:
Life Science/Program Standard III
3.1.3 c. ▲ Cells function and replicate as a results of information stored in DNA and
RNA molecules.
3.2.2 b. ▲ Experiments have shown that all known living organisms contain DNA
or RNA as their genetic material.
3.2.3 c. ▲ DNA (or RNA) provides the instructions that specify the characteristics
of organisms.
The following information is quoted from the web site.
http://www.koshlandsciencemuseum.org/exhibitdna/index.jsp
The extremely long DNA molecule is actually made of a long string of
chemical building blocks called “nucleotides.” There are four different
nucleotides, which are labeled adenine (A), thymine (T), guanine (G), and
cytosine (C). The human genome is made of a sequence of roughly three billion
of these nucleotides. The genome is like a library of instructions.
A gene is a sequence of A’s, T’s, G’s, and C’s that usually provides the
instructions for a single protein component of an organism. The letters of the
genetic alphabet – A, T, G, and C – are meaningless on their own, but they are
combined into useful instructions in genes. Some genes carry enough
information for one complete characteristic of an organism, but most
characteristics result from combinations of genes. Genes are like chapters in the
books that fill the library of the genome.
The sequence of letters within a gene is like the letters in a book of instructions.
Deciphering the enormously long sequence of A’s, T’s, G’s, and C’s in an
organism’s genome reveals useful information. For example, finding a
difference in a gene sequence that governs muscle structure raises questions.
Could the difference affect health? Just as changing one letter in a word can
change its meaning – for example, mice to rice to nice – so changing one DNA
letter can sometimes cause illness.
Not all of the sequences in the genes of two humans are identical. For example,
because your face is unique, the precise set of sequences in the large group of
genes that control the shape of your face are presumably unique too. Some
special parts of the DNA sequence vary from person to person with unusually
high frequency. As you will see, finding sequences in DNA samples can be
used to identify individuals and help solve crimes, even when there are no
eyewitnesses.
DNA MODEL
Procedure:
Materials:
1.8m
1.Take a set of sugar phosphate and place it in
the center of the wire with the phosphate facing
down and twist the wire on top.
2.Take two colored straws (red and blue or
yellow and green) and place them in the center
of the wire.
3.6cm
1.8m
1.8m
3.6cm
1.8m
3.6cm
3. Get 20 small pink
straws pieces (or
two pink straws cut
into 20 pieces)
1.8cm
1.8cm
3.6cm
1.8cm
1.8cm
4. Make a hydrogen bond out of tape and wrap
the joint between the bases. Add a phosphate
and sugar combination straw to each wire.
3.6cm
1.8cm
1. Get 2 clear
straws. Cut each
clear straw into 10
equal pieces.
4. Get 2
meters of
wire
2. Take one 1 blue straw,
1 green straw, 1 red straw, 1
yellow straw. Cut each straw
into 5 equal pieces
Place a pink piece over
each clear piece. The clear
straws represent the
deoxyribose sugar and the
pink straws represent the
phosphate groups.
p
6. Then take the each wire through the other base.
The colored straws represent the nitrogen bases.
Pyrimidines
Name
Date Hr
Purines
Guanine Adenine
C
10. Repeat until there are 10 base pairs.
11. Place the last sugar phosphate on the opposite
side of the first one facing down. Run the wire
through and back down and twist the wire.
4
1
3
74
A
G
2
5
12. Twist the remaining wire to make a loop.
13. Cover the ends with masking tape and label with
name date and hour.
5
6
s
s
p
3
p
9. Add sugar and phosphates.
1
2
T
7. Pyrimidines are smaller than Purines so tuck the
end of the straw for Cytosine into Guanine and
Thymine into Adenine
8. Make a hydrogen bond out of tape and wrap the
joint between the bases.
p
s
5. Take the next pair of bases and thread the wire
through each base.
5. Masking tape
Cytosine Thymine
s
3. Pyrimidines are smaller than purines so tuck
the end of the straw for cytosine into Gaunine
and thymine into adenine.
2.0 m
1.8cm
6
7
Bondbond
14. Hold the top base pair in one hand and the
bottom base pair in the other.
15.Twist in opposite directions. Walah!! A double
helix.
Name
Date
Class
16. Use the model that you made and determine the amino acids.
HR
Amino
Acid t-RNA m-RNA DNA
anticodon
codon
Choose 19 The DNA molecule is shaped like a twisted ladder.
Play the animation. This site is excellent for anything to do with
genetics, heredity, protein synthesis or the genome project.
Translation
Transcription
Replication
Replication
Translation
Transcription
DNA MODEL MAP
http://molvis.sdsc.edu/dna
http://www.mydna.com
Amino
DNA m-RNA t-RNA Acid
p
s
p
s
p
s
p
s
p
s
s
p
p
s
s
p
p
s
s
p
s
p
s
p
p
s
p
s
s
p
p
s
s
p
p
s
s
p
codon
Additional Resources:
Go to these Web sites and check them out. The animated
parts are great.
http://www.dnaftb.org/
http://www.koshlandsciencemuseum.org/exhibitdna/index.jsp
http://www.johnkyrk.com/mitosis.html
anticodon
The DNA Song
(To the tune of Row, Row, Row your Boat)
Say hey, DNA, built a special way
Double helix, ladder shape,
Coiled; that’s what we say
DNA is short, for a longer name.
DE-OXY-RIBONU-CLE-IC A-CID.
We love DNA, made of nucleotides
Phosphate, sugar, and a base,
Bonded down one side.
Adenine and thymine make a lovely pair.
Cytosine without quanine,
would feel very bare.
Then, there’s RNA, has a different base.
In- stead of thymine,
Uracil’s in place.
p
/25 pts DNA QUIZ
/2 1. What are the two classification groups of Nitrogen Bases?
A.
B.
/2 2. What are the two bases for group A in question 1.?
A.
Model 100
____20
Bases are paired correctly
____20
20 Nucleotides were constructed
____20
Phosphates and sugars
are placed correctly and are facing the
correct direction
____20
Model constructed and twisted to show
one complete helix.
____20
Hydrogen bonds are marked in tape and
labeled 2 for A-T or 3 for C-G.
B.
/2 3. What are the two bases for group B in question 1.?
A.
B.
/2 4. What two bases bond with a double hydrogen bond?
/2 5. What two bases bond with a triple hydrogen bond?
Map 98
____20
DNA recorded correctly
____20
Replicated correctly
____20
Transcribed Correctly
____20
Translated correctly
____18
Correct Amino Acids Identified
3 points each
/1 6. What is the D in DNA?
/1 7. What is the shape of DNA?
/2 8. The backbone or side of the ladder are made of alternating
_________&___________.
/1 9. A nucleotide contains what three parts?
________---__________---_________
/1 10. The process of making 2 new DNA daughter strands is called?
/1 11. In the process named in #10 what enzyme unzips the DNA?
/1 12. What enzyme adds the nucleotides to the new strands and proofreads the strand for
accuracy?
/1 13. What enzyme specifically checks for mistakes (alias DNA doctor)?
/2 14. Where can DNA be found in the cell?
/2 15. How is the DNA in the mitochondria different from the DNA in the nucleus?
/2 16. What is the complementary base-pairing rule?
Quiz 25
____ 25 pts
_____/223
Total points
________%