Download Bio 313 worksheet 2 - Iowa State University

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BIO 313 SI
WORKSHEET 2
Supplemental Instruction
Iowa State University
1. Matching
Meischer
a. Discovered DNA has four bases: adenine, guanine, cytosine,
and thymine
Kossel
b. Took high resolution pictures of DNA structure using Xray diffraction techniques
Levene
c. Isolated nuclei from white blood cells, extracts acidic
substance that is rich in phosphorus called nuclein.
Chargaff
d. Determined helical structure of DNA using X-ray
diffraction pictures
Rosalind Franklin
e. Amount of A=T and G=C
Watson and Crick
f. Discovered nucleotides: a unit of DNA consists a sugar, a
phosphate, and a nitrogenous base
2. Which of the bases are purines? Pyrimidines?
3. Draw the four bases found in DNA
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4. What experiment showed that heat-killed IIIS bacteria can genetically transform IIR bacteria into
IIIS bacteria? What was the purpose of this experiment? What would we conclude if the heat
killed IIIS bacteria was treated with RNase and then transformation failed?
5. Describe the 3 layers of DNA structure (ie. Primary, secondary, tertiary)
6. What kind of reaction occurs and what is the resulting bond called in a polynucleotide strand?
7. Why did Hershey and Chase use isotopes in their experiment? What elemental isotopes did they
use and why did they choose those elements?
8. (#21 from chapter 8) DNA molecules of different sizes are often separated with the use of a
technique called electrophoresis. With this technique, DNA molecules are placed in a gel, an
electrical current is applied to the gel, and the DNA molecules migrate toward the positive pole
of the current. What aspect of its structure causes a DNA molecule to migrate toward the
positive pole?
9. A piece of B-DNA winds for 3.5 turns. How many base pairs are there in that stretch of DNA?
How long is it in nm?