Vocabulary: double helix, DNA, enzyme, mutation, nitrogenous base, nucleoside, nucleotide, replication
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
DNA is an incredible molecule that forms the basis of life on Earth. DNA molecules contain instructions for building every living organism on Earth, from the tiniest bacterium to a massive blue whale. DNA also has the ability to replicate, or make copies of itself. This allows living things to grow and reproduce.
1. Look at the DNA molecule shown at right. What does it look like?
The DNA on the right looks like a twisting staircase
This shape is called a double helix.
2. Based on this picture, how do you think a DNA molecule makes a copy of itself? (Hint: Look at the bottom two “rungs” of the ladder.)
An enzyme will be released that will split the DNA and then reconstruct the new sides to have the DNA replicated.
The Building DNA Gizmo™ allows you to construct a DNA molecule and go through the process of DNA replication. Examine the components that make up a DNA molecule.
1. What are the two DNA components shown in the Gizmo?
The two components are nucleosides and phosphates.
2. A nucleoside has two parts: a pentagonal sugar (deoxyribose) and a nitrogenous base (in color). When a nucleoside is joined to a phosphate, it is called a nucleotide.
How many different nitrogenous bases do you see? I saw 4 bases.
Note: The names of these nitrogenous bases are adenine (red), cytosine (yellow), guanine (blue), and thymine (green).
Build a DNA molecule
Get the Gizmo ready:
· If necessary, click Reset to start the building process.
Question: What is the structure of DNA?
1. Build: Follow the steps given in the Gizmo to construct a molecule of DNA. (Note: For simplicity, this DNA molecule is shown in two dimensions, without the twist.)
Stop when the hint reads: “The DNA molecule is complete.” In the spaces at right, list the sequence of nitrogenous bases on the left-hand side of the DNA molecule and the right-hand side.
2. Take a picture: Click the camera () to take a snapshot of your DNA molecule. Right-click the image and select Copy Image. Paste the image into a blank document, and label this image “Original DNA molecule.”
3. Explain: Describe the structure of the DNA molecule you made.
A. What makes up the sides of the DNA molecule? The 4 nitrogenous bases
B. What makes up the “rungs” of the...