DNA Puzzle – Class Set Handout
BACKGROUND INFORMATION:
The control center of the cell is the nucleus. Rodshaped structures in the nucleus called chromosomes
contain the genetic material of the cell. This genetic material
is made of DNA (deoxyribonucleic acid). DNA is found only
in the nucleus of eukaryotic cells cell. Prokaryotic cells contain
DNA floating freely in their cytoplasm because they lack a
nucleus.
The base building unit (monomer) of DNA is the
nucleotide. A DNA nucleotide consists of three parts: a
sugar (deoxyribose), a phosphate and a nitrogen base.
The DNA molecule is in the shape of a double helix,
like a twisted ladder. The "rungs" on the ladder are the
nitrogen bases and the “backbone” (sides) are the sugar and
phosphate. The four different DNA nucleotides are made from
the four different nitrogen bases. cytosine (C), guanine (G),
adenine (A) and thymine (T). According to the base-pairing
rule, cytosine always pairs with guanine and thymine with
adenine. DNA holds the genetic information in the order of its
nitrogen bases. Despite only having 4 nitrogen bases, DNA
can be found in unlimited combinations therefore creating an
endless number of different organisms.
PROCEDURE
1. Read the background information
2. Construct a segment of DNA that has the following bonding sequence on the left side of the “ladder”:
GATCTG
3. Using the base pairing rules, complete the right side of the “ladder”.
4. Have the teacher check the model when completed.
5. Answer the analysis questions in your spiral using complete sentences.
ANALYSIS
1. Sketch and label a picture of the DNA model constructed by the group. Include the following:
deoxyribose, phosphate, adenine, thymine, guanine, cytosine
2. What is DNA and describe its function?
3. What is the monomer (subunit) in DNA? Name the three parts.
4. What is the name of the sugar in DNA?
5. What molecule(s) make up the sides (backbone) of the DNA “ladder”?
6. What molecule(s) make up the steps (rungs) of the DNA “ladder”?
7. How does DNA hold information?
8. Describe the base pairing rules of DNA.
9. The sequence of nitrogenous bases on one strand of a DNA molecule is GGCAGTTCATGC. What
would be the sequence of bases on the complementary strand?
10. If there are only 4 nucleotide types in DNA, why are all living things so different?
11. How many nucleotides are shown in this picture?
G
A
A
G
G
A
C
C
G
A
G
T
A
G
T