Download Modeling DNA Structure and Function

Exercise 9 - Biology 105
Modeling DNA Structure and Function
Objectives:
1. Understand the structure of a DNA molecule.
2. Understand how DNA transfers information.
3. Reinforce material from Modules 10.1 - 10.16 in your text
Introduction:
Deoxyribonucleic acid is a molecule that carries genetic information. The
information contained in the molecule encodes protein structure, ribosomal RNA structure, and gene
regulation. The structure of the molecule also allows DNA to make copies of itself.
Methods: In this lab you will build a model DNA molecule and also model some of its functions.
I. DNA Structure: Use the paper model nucleotides provided to build a model of a DNA molecule that
is 12 base pairs long. Study drawings and descriptions in a textbook to aid your understanding of the
proper structure.
Upon completion of the model, be able to answer the following questions for your instructor. Be able to
point to the various structures asked about below on your model.
1. What is a nucleotide?
2. Are all the nucleotides the same ? Explain.
3. What are the three components of a nucleotide ?
4. What is a base pair?
5. If the DNA molecule is compared to a ladder, where are the 'rungs' and 'rails' of the molecule?
6. Where are the bonds ( and what kind ) that bond one base to another?
7. Where are the bonds ( and what kind ) that bond the sugars to the phosphates?
8. Using your model as a guide, draw part of a DNA molecule.
9. In your own words, write a paragraph describing the structure of the DNA molecule.
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II. Replication: Using your model as a guide, in your own words describe how a DNA molecule
replicates itself. Be sure to use these terms in your answer: nucleotide, hydrogen bond, template.
Using your model as a guide, draw what occurs during replication.
III. Transcription Using the DNA molecule that you've just created, do the following:
Build an mRNA molecule that is complementary to one of the DNA strands -- the so called template
strand. That is, show your instructor what would happen if the DNA was being transcribed.
IV. Translation: Use your mRNA as a blueprint for a polypeptide. In the space provided above, next
to the mRNA sequence, draw the amino acid sequence that would be produced during translation. (To
do this, you'll have to be able to interpret the genetic code as it appears in your text.)
1. How many bases make up one codon?
2. How many codons are present in the mRNA strand you made in lab?
3. On what kind of molecule do you find an anticodon?
Review:
DNA Æ RNA Æ protein
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1. What process does each arrow above stand for ?
2. Where in a eukaryotic cell does each process occur ?
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