Download Page 1 -- ·- • • • Molecular Genetics Seminar #1 DNA From The

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Molecular Genetics Seminar #1
DNA From The Beginning
Molecules of Genetics (Modules 15-28)
1. How and when did Friedtich Miescher discover nucleic acids and what did he think its
function was? What did he cal1 it? (Module 15)
2. Describe the structure of proteins and why scientists believed they were the best
candidates for the molecules of heredity as compared to DNA.
3. Describe a nucleotide and where the nitrogenous base, hydroxyl and phosphate groups
are attached as discovered by Phoebus Levene. What are the four different nitrogenous
bases? How are these bases attached to each other in DNA?
4. Describe Beadle and Tatum's experiments that supported the idea that one gene makes
one enzyme or protein using the biochemical steps for making the amino acid arginine in
the bread mold Neurospora. (Module 16)
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1. Describe Fred Griffith's 1928 experiments with Pneumococcus and mice that
demonstrated that there was a transforming molecule that changed Pneumoccus cells
without capsules into cells with capsules. (Or changed the R strain into an S strain).
(Module 17)
2. Desclibe how Oswald A very and his colleagues proved that the transforming molecule
in Griffith's experiment was DNA.
3. Describe Joshua Lederberg's experiments that proved that bacteria have sex
(conjugation). (Module 18)
4. Describe how the order of bacterial genes was determined using conjugation.
5. Describe how Alfred Hershey and Martha Chase used bacteriophages to prove that
DNA was the hereditary molecule .
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1. What did Watson and Crick already know about DNA before discovering its
structure? (Module 19)
2. ·.vhat did Erwin Chargaff discover about DNA from various organisms and how did
Watson and Crick use this information in determining DNA's structure?
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3. What did Linus Pauling at Cal Tech do that helped Watson and Crick?
4. How did Maurice Wilkins and Rosalind Franklin's X-ray diffraction patterns of DNA
help Watson and Crick?
5. How did Watson and Crick's model of DNA explain how the molecule could copy
itself?
1. How did Matthew Meselson and Frank Stahl prove Watson and Crick's description of
how DNA replicates? (Module 20)
2. Explain how Arthur Kornberg proved Watson and Crick's description of how DNA
replicates. Which DNA polymerase play's the major role in DNA replication?
3. DNA is located in the nucleus of the cell, but proteins are made outside the nucleus on
the ribosomes in the cytoplasm. What was Francis Crick's proposed explanation for how
DNA could direct the synthesis of proteins in the cyctoplasm when it was in the nucleus?
(Module 21)
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4. Describe Crick's Central Dogma and explain the differences between DNA and RNA.
What did he say about how amino acids interact with the carrier or messenger RNA?
5. What is the reasoning that Crick went through to determine the nature of the genetic
code: the sequence of A's, T's, C's and G's in DNA?
1. How did Marshall Nirenberg and Har Khorana crack the genetic code? (Module 22)
2. They discovered that the code was redundant. Explain what that means.
3. Explain how DNA directs the synthesis of specific proteins using the genetic code.
Do not leave out any steps. What are the start and stop codons?
4. Translate the following mRNA sequence into an amino acid sequence using the
Genetic Code Table: AUG CGG AUA AAA AUA UCC.
5. What is a frame shift mutation?
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1. Describe Fred Sanger's method of sequencing the order of DNA nucleotides in a gene.
(Module 23) Include in your description the role of the following: dideoxynucleotides
with radioactive phosphorus (chain terminators); polyacrylamide gels and how these gels
reveal the order of nucleotides in a DNA molecule on the x-ray film placed over the gel.
2. How did Rich Roberts and Phil Sharp discover introns or non-coding segments in
DNA? (Module 24) Include the role of the following in your explanation: restriction
endonucleases or restriction enzymes; agarose gel electrophoresis; ethidium bromide;
electron microscope and DNA/RNA hybrids and R-loopes
3. Describe what a retrovirus is and how it altered the Central Dogma. (Module 25)
4. How are retroviruses used to insert missing genes into cells?
1. Describe what a mutation is and all the possible causes (Module 27)
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Describe the following type of mutations: point mutation; frameshift mutation.
3. Why would evolution be impossible without mutations?
4. Describe 2 ways mutated DNA is repaired by the cells.
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