Exam (elaborations) Gizmos L1 Lab Building DNA.

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. Look at the DNA molecule shown at right. What does it look like? A double helix where two strands are twisting around each other. 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.) I would think the two rungs at the bottom of the ladder would connect to create a copy of the DNA molecule. Gizmo Warm-up 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. What are the two DNA components shown in the Gizmo? A pentagonal sugar and a nitrogenous base. 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? 4 Note: The names of these nitrogenous bases are adenine (red), cytosine (yellow), guanine (blue), and thymine (green).