BIO 202 FINAL SOLUTION SET 2026
QUESTIONS WITH SOLUTIONS GRADED A+
⩥ Hershey-Chase Experiment. Answer: tested that DNA is genetic
material not protein; used a T2 phage (a virus) that binds to a cell, drills
a hole, and injects their genes into the bacterium; DNA was labeled 32P /
Protein 35S; the viral genes would be in the pellet (32P) while 35S was
in solution
⩥ Messalson-Stahl Experiment. Answer: changed the weight of DNA yb
growing bacteria in media with different types of nitrogen (14N/15N);
Generation 0 (all 15N); Generation 1: all DNA was hybrid (meaning one
size) ruling out the conservative model; Generation 2: half DNA was
14N and half was hybrid (semiconservative model)
⩥ Semiconservative Replication Model. Answer: original parental strand
is pulled apart from double helix, then each strand serves as a template
for new complimentary strands
⩥ Conservative Replication Model. Answer: some enzymes leave
original DNA intact, but read it somehow to make a new identical
double stranded DNA
,⩥ Dispersive Replication Model. Answer: original DNA molecule
strands get pulled apart and chopped into pieces; then new DNA is
synthesized to switch the pieces together (a mixture)
⩥ Replication Bubble. Answer: replication site; origin of replication
⩥ Replication forks. Answer: 2 at each bubble - where you transition
from the single strands (separated) to where the parental strand is still
doubled
⩥ Bacterial replication. Answer: only have a single origin of replication;
5' to 3' direction
⩥ Eukaryotic Replication. Answer: DNA is bidirectional since both
original strands serve as a template; parental strand (serves as a template
which determines the growing daughter strand); new nucleotides are
added to the 3' -OH of the last nucleotide; daughter strand grows in a 3'
to 5' direction on the parental because it only grows 5' to 3'
⩥ DNA Polymerase. Answer: enzyme that carries out the formation of
phosphodiester bonds (synthesizes the new strand); can only add new
nucleotides to the 3' of a chain and requires a free hydroxyl group
⩥ DNA Polymerase III. Answer: adds new deoxyribonucleotides to the
3' end of an RNA primer; extends the new strand/okazaki fragment
, ⩥ Primase. Answer: creates a short RNA primer to provide a 3' -OH unto
which new nucleotides can be added by DNA polymerase
⩥ Helicase. Answer: (at replication fork) unzips the DNA double strand
by catalyzing the breaking of hydrogen bonds between base pairs to
open DNA
⩥ SSBPs. Answer: single stranded DNA binding proteins (at replication
fork); stabilizes single stranded DNA; right behind helicase to prevent
reannealing; binds non-specifically
⩥ topoisomerase. Answer: (at replication fork) keeps DNA from getting
snarled up by relieving twisting forces
⩥ Leading Strand. Answer: synthesized in the same direction as fork is
unwinding (5' to 3') so it undergoes continuous synthesis
⩥ Lagging Strand. Answer: 3' to 5' direction; primer is added--first
fragment synthesized by sliding clamp and DNA pol III---second
fragment is synthesized--primer is replaced by DNA pol I that switches
the nucleotides with deoxyribonucleotides--gap is sealed by ligase
⩥ DNA Polymerase I. Answer: removes the RNA primer and replaces it
with DNA; At the ends of the chromosomes, a piece of the lagging
QUESTIONS WITH SOLUTIONS GRADED A+
⩥ Hershey-Chase Experiment. Answer: tested that DNA is genetic
material not protein; used a T2 phage (a virus) that binds to a cell, drills
a hole, and injects their genes into the bacterium; DNA was labeled 32P /
Protein 35S; the viral genes would be in the pellet (32P) while 35S was
in solution
⩥ Messalson-Stahl Experiment. Answer: changed the weight of DNA yb
growing bacteria in media with different types of nitrogen (14N/15N);
Generation 0 (all 15N); Generation 1: all DNA was hybrid (meaning one
size) ruling out the conservative model; Generation 2: half DNA was
14N and half was hybrid (semiconservative model)
⩥ Semiconservative Replication Model. Answer: original parental strand
is pulled apart from double helix, then each strand serves as a template
for new complimentary strands
⩥ Conservative Replication Model. Answer: some enzymes leave
original DNA intact, but read it somehow to make a new identical
double stranded DNA
,⩥ Dispersive Replication Model. Answer: original DNA molecule
strands get pulled apart and chopped into pieces; then new DNA is
synthesized to switch the pieces together (a mixture)
⩥ Replication Bubble. Answer: replication site; origin of replication
⩥ Replication forks. Answer: 2 at each bubble - where you transition
from the single strands (separated) to where the parental strand is still
doubled
⩥ Bacterial replication. Answer: only have a single origin of replication;
5' to 3' direction
⩥ Eukaryotic Replication. Answer: DNA is bidirectional since both
original strands serve as a template; parental strand (serves as a template
which determines the growing daughter strand); new nucleotides are
added to the 3' -OH of the last nucleotide; daughter strand grows in a 3'
to 5' direction on the parental because it only grows 5' to 3'
⩥ DNA Polymerase. Answer: enzyme that carries out the formation of
phosphodiester bonds (synthesizes the new strand); can only add new
nucleotides to the 3' of a chain and requires a free hydroxyl group
⩥ DNA Polymerase III. Answer: adds new deoxyribonucleotides to the
3' end of an RNA primer; extends the new strand/okazaki fragment
, ⩥ Primase. Answer: creates a short RNA primer to provide a 3' -OH unto
which new nucleotides can be added by DNA polymerase
⩥ Helicase. Answer: (at replication fork) unzips the DNA double strand
by catalyzing the breaking of hydrogen bonds between base pairs to
open DNA
⩥ SSBPs. Answer: single stranded DNA binding proteins (at replication
fork); stabilizes single stranded DNA; right behind helicase to prevent
reannealing; binds non-specifically
⩥ topoisomerase. Answer: (at replication fork) keeps DNA from getting
snarled up by relieving twisting forces
⩥ Leading Strand. Answer: synthesized in the same direction as fork is
unwinding (5' to 3') so it undergoes continuous synthesis
⩥ Lagging Strand. Answer: 3' to 5' direction; primer is added--first
fragment synthesized by sliding clamp and DNA pol III---second
fragment is synthesized--primer is replaced by DNA pol I that switches
the nucleotides with deoxyribonucleotides--gap is sealed by ligase
⩥ DNA Polymerase I. Answer: removes the RNA primer and replaces it
with DNA; At the ends of the chromosomes, a piece of the lagging
