BIO 311C EXAM 3 STUDY GUIDE QUESTIONS AND ANSWERS 2026/2027 |
COMPLETE EXAM REVIEW
What were early arguments supporting each of the following hypotheses? a) protein is the
genetic material b) DNA is the genetic material - ANS ✔✔a) Protein as genetic material
- 20 Amino Acids
- huge variety
- enzymes control reactions
b) DNA as genetic material
- 4 nucleotides
- long and stringy
- stays in nucleus
- transforming molecule- rats
- viruses: was it protein or DNA?
Chromosomes made of DNA proteins
How did Griffiths discover the "transforming principle" in pneumonia-causing bacteria? - ANS
✔✔Griffiths found that the smooth virus was deadly (capsule) while the rough virus was not
deadly. He injected heat killed s virus and live r virus into a mouse and found that the
combination was deadly. R virus was transformed to s by an unknown, heritable substance that
allows r to make a capsule.
How did investigators Hershey and Chase use radioactively labeled bacteriophage (viral)
particles to determined that the genetic material was indeed DNA and not protein. - ANS
, ✔✔Labeled some phages with radioactive sulfur and others with radioactive phosphorus. Sulfur
bonded to the protein coat of the virus and phosphorus bonded to DNA. When centrifuged,
phosphorus was found in the pellet while sulfur is found in supernatant fluid. This indicated that
DNA is the molecule of heredity.
What various types of data were used by Watson and Crick to determine the structure of DNA? -
ANS ✔✔Wilkins x ray crystallography of DNA, showed double helix and proportion of
nitrogenous bases. Franklin said hydrophobic bases would be on the interior. Bases had to have
uniform size of purines pair with pyrimidines. A-T, G-C
Describe the structure of DNA nucleotide components (phosphate, sugar, ATCG bases), their
arrangement in DNA, and the types of bonds (hydrogen or covalent) between various
components. - ANS ✔✔Sugar is covalently bonded to phosphate group on 5' carbon.
Nitrogenous base is covalently bonded to 1' carbon of sugar. Bases are bonded with H bonds
between them. A--T, G---C
What are 3' and 5' ends of DNA, what is meant by the "anti-parallel" structure of DNA? - ANS
✔✔3' is the 3' carbon, 5' is where phosphate group is bonded. Run antiparallel so one side will
have the phosphate group sticking out while the other will have the 3' carbon of the sugar
exposed.
How did Meselson and Stahl use bacteria to determine that DNA replication is semi
conservative? - ANS ✔✔Grow DNA in heavy nitrogen and then put it in an environment with
lighter nitrogen, it was allowed to replicate once and then centrifuged, found that it was a
hybrid weight so it was a combination of heavy and light- semi conservative. This was further
proven when it was allowed to replicate a second time and there was a light and hybrid density.
Describe the process of DNA replication, including: major enzymes (helicase, primase, DNA
polymerase, ligase), role of primers for starting, use of triphosphate nucleosides as building
blocks (and energy), and the addition of new nucleotides to the 3' end of the growing strand. -
ANS ✔✔Helicase unwinds and unzips the double helix of DNA. Factors hold the strands apart
while primase lays down primer going 5'-3'. DNA polymerase III adds nucleoside triphosphate
bases and hydrolyzes phosphate to power addition of bases. There bases are added in a semi
COMPLETE EXAM REVIEW
What were early arguments supporting each of the following hypotheses? a) protein is the
genetic material b) DNA is the genetic material - ANS ✔✔a) Protein as genetic material
- 20 Amino Acids
- huge variety
- enzymes control reactions
b) DNA as genetic material
- 4 nucleotides
- long and stringy
- stays in nucleus
- transforming molecule- rats
- viruses: was it protein or DNA?
Chromosomes made of DNA proteins
How did Griffiths discover the "transforming principle" in pneumonia-causing bacteria? - ANS
✔✔Griffiths found that the smooth virus was deadly (capsule) while the rough virus was not
deadly. He injected heat killed s virus and live r virus into a mouse and found that the
combination was deadly. R virus was transformed to s by an unknown, heritable substance that
allows r to make a capsule.
How did investigators Hershey and Chase use radioactively labeled bacteriophage (viral)
particles to determined that the genetic material was indeed DNA and not protein. - ANS
, ✔✔Labeled some phages with radioactive sulfur and others with radioactive phosphorus. Sulfur
bonded to the protein coat of the virus and phosphorus bonded to DNA. When centrifuged,
phosphorus was found in the pellet while sulfur is found in supernatant fluid. This indicated that
DNA is the molecule of heredity.
What various types of data were used by Watson and Crick to determine the structure of DNA? -
ANS ✔✔Wilkins x ray crystallography of DNA, showed double helix and proportion of
nitrogenous bases. Franklin said hydrophobic bases would be on the interior. Bases had to have
uniform size of purines pair with pyrimidines. A-T, G-C
Describe the structure of DNA nucleotide components (phosphate, sugar, ATCG bases), their
arrangement in DNA, and the types of bonds (hydrogen or covalent) between various
components. - ANS ✔✔Sugar is covalently bonded to phosphate group on 5' carbon.
Nitrogenous base is covalently bonded to 1' carbon of sugar. Bases are bonded with H bonds
between them. A--T, G---C
What are 3' and 5' ends of DNA, what is meant by the "anti-parallel" structure of DNA? - ANS
✔✔3' is the 3' carbon, 5' is where phosphate group is bonded. Run antiparallel so one side will
have the phosphate group sticking out while the other will have the 3' carbon of the sugar
exposed.
How did Meselson and Stahl use bacteria to determine that DNA replication is semi
conservative? - ANS ✔✔Grow DNA in heavy nitrogen and then put it in an environment with
lighter nitrogen, it was allowed to replicate once and then centrifuged, found that it was a
hybrid weight so it was a combination of heavy and light- semi conservative. This was further
proven when it was allowed to replicate a second time and there was a light and hybrid density.
Describe the process of DNA replication, including: major enzymes (helicase, primase, DNA
polymerase, ligase), role of primers for starting, use of triphosphate nucleosides as building
blocks (and energy), and the addition of new nucleotides to the 3' end of the growing strand. -
ANS ✔✔Helicase unwinds and unzips the double helix of DNA. Factors hold the strands apart
while primase lays down primer going 5'-3'. DNA polymerase III adds nucleoside triphosphate
bases and hydrolyzes phosphate to power addition of bases. There bases are added in a semi
