Molecular genetics Exam Questions with Correct
Answers
1. Explain how the experiments that each of the following
people/groups per- formed provided evidence that DNA is the
genetic material.
Frederick Griffith correct answers: Take rough strain of streptococcus pneumonia inject it into
the mouse and mouse would be happy. Injected the smooth/ virulent type into a mouse and it would
die. Injected an evil smooth strain and heated it up before and when injected into the mouse, the mouse
was okay. When he took the rough strain, which normally doesn't hurt anything and mixed it with the
heat killed smooth strain which normally doesn't hurt the mouse at all, the mouse died. He learned that
there was a transforming factor. Something was being transferred from the dead smooth strain to the
live rough strain and transforming it to virulent.
2. Explain how the experiments that each of the following
people/groups per-
formed provided evidence that DNA is the genetic material.
Oswald Avery, Maclyn McCarty, and Colin MacLeod correct answers: They
looked at Griflth's experiment and tried to figure out what the transforming factor was. They
found RNA, Protein, and DNA. They used enzymes that broke down each of those to see if they could
transform the bacteria again. Added ribonuclease and broke down RNA and
it was still able to transform. They added enzymes to break down proteins and they were still able to
transform. They added deoxyribonuclease which breaks down DNA and then they couldn't transform.
They figured out that DNA was the transforming factor.
3. Explain how the experiments that each of the following
people/groups per-
formed provided evidence that DNA is the genetic material.
Alfred Hershey and Martha Chase correct answers: Used sulfur in one experiment and
in this they used a red dye to dye the bacteriophages in the experiment. They infect the bacteria,
blend it all up, precipitate it out and see what color came out. It's important they used sulfur because it
is found in proteins, but not in DNA (many people thought proteins were the transforming factor). They
used a ditterent dye to dye phosphorous, which is found in DNA, but not in proteins. They showed the
only one doing the transforming was the green dye. That means it was the phosphorous, so proteins
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,were not responsible for transforming. Conclusion correct answers: DNA was hereditary material
4. Explain how the experiments that each of the following
people/groups per-
formed provided evidence that DNA is the genetic material.
Erwin Chargaff correct answers: Looking at ditterent organisms and studying the amount of As,
Ts, Cs, and Gs. He found that amount of A and T is exactly the same. Chargatt's rule
5. Explain why the peanut plant in Mr. Anderson's DNA and RNA
video is able to express a gene from B. thuringiensis (Bt). correct answers:
The peanut plant can express a gene from B. thuringiensis because DNA is the same
and can be transferred from one organism to another.
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, 6. Describe the structure of a eukaryotic chromosome. How does it
compare to a prokaryotic chromosome? correct answers: Prokaryotic
Chromosomal DNA in cytoplasm
Circular chromosome/ loop shape
Made only of DNA no histone
proteins
Eukaryotic
Chromosomal DNA in nucleus only
Linear chromosomes (looks like an
x)
DNA tightly coiled around histone proteins
7. Describe the characteristics of the DNA molecule that make it a
good infor- mation-bearing molecule. correct answers: It has the same bases.
(universal bases).
Easy to copy because of hydrogen bonds and nucleotide base
pairing Its really small.
Their protected by a phosphate sugar backbone so it's hard to damage
It's self replicating...able to make copies of itself to pass on the information while also staying in tact
8. Explain why DNA replication is considered to be semiconservative.
Why is the leading strand replicated continuously, while the lagging
strand is replicated discontinuously? correct answers: Semiconservative DNA
replication correct answers: Produces two copies of one of the strands...one is the original and one
is the new copy.The two new strands will join together and then the two old ones will zip back together. Using
part of the old molecule to make the new molecule.
Leading strand is replicated continuously because RNA polymerase can only continuously add nucleotide
bases in the 5' to 3' direction. The other strand goes in the 3' to 5' direction and can only make several
fragments called okazaki fragments. Ligase is needed to join the fragments.
9. Francis Crick coined the term "central dogma" with regard to the
relationship
between DNA and RNA. Explain what Crick meant by this. correct answers:
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Answers
1. Explain how the experiments that each of the following
people/groups per- formed provided evidence that DNA is the
genetic material.
Frederick Griffith correct answers: Take rough strain of streptococcus pneumonia inject it into
the mouse and mouse would be happy. Injected the smooth/ virulent type into a mouse and it would
die. Injected an evil smooth strain and heated it up before and when injected into the mouse, the mouse
was okay. When he took the rough strain, which normally doesn't hurt anything and mixed it with the
heat killed smooth strain which normally doesn't hurt the mouse at all, the mouse died. He learned that
there was a transforming factor. Something was being transferred from the dead smooth strain to the
live rough strain and transforming it to virulent.
2. Explain how the experiments that each of the following
people/groups per-
formed provided evidence that DNA is the genetic material.
Oswald Avery, Maclyn McCarty, and Colin MacLeod correct answers: They
looked at Griflth's experiment and tried to figure out what the transforming factor was. They
found RNA, Protein, and DNA. They used enzymes that broke down each of those to see if they could
transform the bacteria again. Added ribonuclease and broke down RNA and
it was still able to transform. They added enzymes to break down proteins and they were still able to
transform. They added deoxyribonuclease which breaks down DNA and then they couldn't transform.
They figured out that DNA was the transforming factor.
3. Explain how the experiments that each of the following
people/groups per-
formed provided evidence that DNA is the genetic material.
Alfred Hershey and Martha Chase correct answers: Used sulfur in one experiment and
in this they used a red dye to dye the bacteriophages in the experiment. They infect the bacteria,
blend it all up, precipitate it out and see what color came out. It's important they used sulfur because it
is found in proteins, but not in DNA (many people thought proteins were the transforming factor). They
used a ditterent dye to dye phosphorous, which is found in DNA, but not in proteins. They showed the
only one doing the transforming was the green dye. That means it was the phosphorous, so proteins
1/
17
,were not responsible for transforming. Conclusion correct answers: DNA was hereditary material
4. Explain how the experiments that each of the following
people/groups per-
formed provided evidence that DNA is the genetic material.
Erwin Chargaff correct answers: Looking at ditterent organisms and studying the amount of As,
Ts, Cs, and Gs. He found that amount of A and T is exactly the same. Chargatt's rule
5. Explain why the peanut plant in Mr. Anderson's DNA and RNA
video is able to express a gene from B. thuringiensis (Bt). correct answers:
The peanut plant can express a gene from B. thuringiensis because DNA is the same
and can be transferred from one organism to another.
2/
17
, 6. Describe the structure of a eukaryotic chromosome. How does it
compare to a prokaryotic chromosome? correct answers: Prokaryotic
Chromosomal DNA in cytoplasm
Circular chromosome/ loop shape
Made only of DNA no histone
proteins
Eukaryotic
Chromosomal DNA in nucleus only
Linear chromosomes (looks like an
x)
DNA tightly coiled around histone proteins
7. Describe the characteristics of the DNA molecule that make it a
good infor- mation-bearing molecule. correct answers: It has the same bases.
(universal bases).
Easy to copy because of hydrogen bonds and nucleotide base
pairing Its really small.
Their protected by a phosphate sugar backbone so it's hard to damage
It's self replicating...able to make copies of itself to pass on the information while also staying in tact
8. Explain why DNA replication is considered to be semiconservative.
Why is the leading strand replicated continuously, while the lagging
strand is replicated discontinuously? correct answers: Semiconservative DNA
replication correct answers: Produces two copies of one of the strands...one is the original and one
is the new copy.The two new strands will join together and then the two old ones will zip back together. Using
part of the old molecule to make the new molecule.
Leading strand is replicated continuously because RNA polymerase can only continuously add nucleotide
bases in the 5' to 3' direction. The other strand goes in the 3' to 5' direction and can only make several
fragments called okazaki fragments. Ligase is needed to join the fragments.
9. Francis Crick coined the term "central dogma" with regard to the
relationship
between DNA and RNA. Explain what Crick meant by this. correct answers:
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