Bio H – Molecular Biology
DNA Model Kit
Begin by checking your kit for the following components:
Pieces
Red straws
White straws (rigid)
Blue straws
Gray Straws
Black with 3 prongs
Yellow with 2 prongs
White with 2 prongs
White flexible tubes
Long green or gray straw
Black or gray with 4 prongs
What they represent
Adenine base (A)
Thymine base (T)
Guanine Base (G)
Cytosine Base (C)
Deoxyribose sugar
Phosphate group
Hydrogen bond
Phosphodiester (covalent) bond
Support for helix
Support stand
Objective: To build a 3D helical model of DNA by linking together nucleotides in the proper arrangement.
Procedure:
1. Begin by building 10 separate nucleotides. Make sure each nucleotide has a Sugar, a Phosphate and a Base
and that the pieces are linked together using the proper bond.
Show me your 10 nucleotides BEFORE linking them and I will sign here ______________
2. When you are done building the 10 nucleotides, use 5 of them to build a SINGLE chain with the following
sequence: AGACT
3. Once you have that chain built, match the remaining 5 nucleotides to fill in the second chain. Make sure you
are pairing up complementary bases! Also make sure that the correct bond is between bases
4. Once your DNA ladder is complete, twist all the center hydrogen bonds so the center holes face down.
Thread the LONG light green straw through all those center holes.
5. Show me your completed model and I will sign here _______________________.
Bio H – Molecular Biology
Questions:
1. Differentiate between hydrogen bonds and covalent bonds in terms of both their strength and location in
the DNA double helix.
2. What is the significance of the sequence of bases?
3. Why is it that only certain bases can “pair up?”
4. How does replication ensure the information in one cell gets passed on exactly as it is to another cell?
5. Say DNA polymerase makes a mistake during replication and inserts a G where there should be a T.
What is the formal name for this “mistake?”
6. What is the only time that DNA replication is necessary?