For this lab, you will build a model of DNA and then submit a photo of your model.

First of all, you will need to understand the structure of DNA. Read through page 4 of this material.

Recall that A and T bases are complementary and G and C bases are complementary to each other. Complementary bases of each DNA strand form hydrogen bonds with one another.

Be creative and choose 4 different types of objects to serve as DNA bases and then develop a key. Your key should show what object type corresponds to which DNA base.

Next, use two pieces of string or some other long objects as the phosphate sugar backbones of DNA and then place your objects between the strings to model the structure of DNA. Your DNA model must have 20 nucleotides in order to get full credit.

Take a clear photo of your model and include a written copy of your key in the photo. The key must have the current date written on it. All of the writing should be readable and the photo should be in .jpg format and approximately 75kb to 1MB.

Submit the photo using the assignment link listed below.
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Added on 20.06.2016 20:34
DNA structure

Here is a link to the media file dna_close-up.swf..

8.4 The Discovery of DNA”s Structure

A. DNA”s Building Blocks

1. DNA is composed of four kinds of nucleotides, each of which consists of:

a. A five-carbon sugardeoxyribose;

b. A phosphate group; and

c. One of four basesadenine (A), guanine (G), thymine (T), or cytosine (C).

2. The nucleotides are similar, but T and C are single-ring pyrimidines; A and G are double-ring purines.

3. Edwin Chargaff, in 1950, noted two critical bits of data.

a. The four kinds of nucleotide bases making up a DNA molecule differ in relative amounts from species to species.

b. The amount of A = T, and the amount of G = C.

3. James Watson and Francis Crick were using chemical bonding to predict the structure of DNA.

4. Rosalind Franklin used x-ray diffraction techniques to produce images of DNA molecules.

a. DNA exists as a long, thin molecule of uniform diameter.

b. The structure is highly repetitive.

c. DNA is helical.

B. DNA”s Base Pair Sequence

1. The following features were incorporated into Watson and Crick”s models.

a. Single-ringed thymine was hydrogen bonded with double-ringed adenine, and single-ringed cytosine with double-ringed guanine, along the entire length of the molecule.

b. The backbone was made of chains of sugar-phosphate linkages.

c. The molecule was double stranded and looked like a ladder with a twist to form a double helix.

2. The base pairing is constant for all species, but the sequence of base pairs in a nucleotide strand is different from one species to the next.