NCSSM MolGen Winter 2025-Questions and Correct
Verified Answers
Post World War II - ✔✔After this, there was penicillin and antibodies as well as a large
increase in radioactive research
Alfred Hershey and Martha Chase (1952) - ✔✔Bacteriophage and blender expt. suggested
DNA as genetic material
Avery, McCarthy, and MacLeod (1944) - ✔✔lysed (heat-killed) smooth cells, mixed them
with rough cells and injected them into mice(each mixture was treated with protases, DNAses, or
RNAses). This determined the transforming factor in cells (DNA).
Bacteriophage - ✔✔A virus that infects bacteria; within one hour around 200 of these are
made, and within 20 minutes the virus' DNA is in the bacterial cell
Hershey and Chase (1952) - ✔✔these scientists took radioactive phosphorus (32p),
radioactive sulfur (35s), regular phosphorus (31p), and regular sulfur (32s) to begin radioactive
labelling. This proves genes are DNA
Watson and Crick - ✔✔developed double stranded DNA that is on an "axis" (not a physical
one, but like the model it is invisible).
Double Helix DNA - ✔✔Two long polynucleotide strands, a leading strand (5'--> 3') and a
lagging strand (3'-->5'). The sugar is perpendicular to the base; the base is on the inside, the
sugar and phosphate are on the outside of the strand. Each is held together by hydrogen bonds.
Linus Pauling - ✔✔developed a triple helix structure, with a base on the outside and the
phosphate on the inside (opposite of what we know today)
, Erwin Chargaff (1950) - ✔✔Analyzes the base composition of DNA in cells. He discovers
that the amounts of adenine and thymine are almost always equal, as are the amounts of guanine
and cytosine.
Rosalind Franklin and Maurice Wilkins - ✔✔Used x-ray crystallography to study DNA
structure
2 nanometers wide - ✔✔double stranded DNA molecule
.34 nanometers - ✔✔how long is each base pair?
keto tautomer - ✔✔has a C=O and an additional C-H bond
hydrogen bond - ✔✔*really* weak bond between A, T and C,G. Weak alone, but together
they're strong
human genome - ✔✔3.2*10^9 base pairs (on one side); approximately 7.14 feet per cell.
Angstrom unit - ✔✔10^-10 meters, DNA is approximately 10 Angstroms
Meselson-Stahl Experiment - ✔✔Used isotope of nitrogen to change the weight of DNA N15
& N14, demonstrated that the semi-conservative model is the best description of replication.
semi-conservative replication - ✔✔in each new DNA double helix, one strand is from the
original molecule, and one strand is new.
replication fork - ✔✔A Y-shaped region on a replicating DNA molecule where new strands
are growing. There are multiple in one strand of DNA.
Verified Answers
Post World War II - ✔✔After this, there was penicillin and antibodies as well as a large
increase in radioactive research
Alfred Hershey and Martha Chase (1952) - ✔✔Bacteriophage and blender expt. suggested
DNA as genetic material
Avery, McCarthy, and MacLeod (1944) - ✔✔lysed (heat-killed) smooth cells, mixed them
with rough cells and injected them into mice(each mixture was treated with protases, DNAses, or
RNAses). This determined the transforming factor in cells (DNA).
Bacteriophage - ✔✔A virus that infects bacteria; within one hour around 200 of these are
made, and within 20 minutes the virus' DNA is in the bacterial cell
Hershey and Chase (1952) - ✔✔these scientists took radioactive phosphorus (32p),
radioactive sulfur (35s), regular phosphorus (31p), and regular sulfur (32s) to begin radioactive
labelling. This proves genes are DNA
Watson and Crick - ✔✔developed double stranded DNA that is on an "axis" (not a physical
one, but like the model it is invisible).
Double Helix DNA - ✔✔Two long polynucleotide strands, a leading strand (5'--> 3') and a
lagging strand (3'-->5'). The sugar is perpendicular to the base; the base is on the inside, the
sugar and phosphate are on the outside of the strand. Each is held together by hydrogen bonds.
Linus Pauling - ✔✔developed a triple helix structure, with a base on the outside and the
phosphate on the inside (opposite of what we know today)
, Erwin Chargaff (1950) - ✔✔Analyzes the base composition of DNA in cells. He discovers
that the amounts of adenine and thymine are almost always equal, as are the amounts of guanine
and cytosine.
Rosalind Franklin and Maurice Wilkins - ✔✔Used x-ray crystallography to study DNA
structure
2 nanometers wide - ✔✔double stranded DNA molecule
.34 nanometers - ✔✔how long is each base pair?
keto tautomer - ✔✔has a C=O and an additional C-H bond
hydrogen bond - ✔✔*really* weak bond between A, T and C,G. Weak alone, but together
they're strong
human genome - ✔✔3.2*10^9 base pairs (on one side); approximately 7.14 feet per cell.
Angstrom unit - ✔✔10^-10 meters, DNA is approximately 10 Angstroms
Meselson-Stahl Experiment - ✔✔Used isotope of nitrogen to change the weight of DNA N15
& N14, demonstrated that the semi-conservative model is the best description of replication.
semi-conservative replication - ✔✔in each new DNA double helix, one strand is from the
original molecule, and one strand is new.
replication fork - ✔✔A Y-shaped region on a replicating DNA molecule where new strands
are growing. There are multiple in one strand of DNA.
