©FYNDLAY.
MCB4403 - Chp 7 Exam Questions And
Answers 100% Verified.
7.1 Discuss the evidence that led researchers to identify DNA as the genetic material of cellular
organisms. - Answers✔- Oswald Avery, and colleagues discovered that they could kill a mouse
that had live but harmless (avirulent) streptococcus pneumonia, plus dead cells from a virulent
strain of bacteria.
- the transforming agent is DNA.
-also coincidentally discovered the first of several mechanisms of horizontal gene transfer
between microbes.
What is transformation? - Answers✔The internalization of free DNA from the environment into
bacterial cells.
What do viruses such as influenza and SARS-CoV-2 use for their genetic material? -
Answers✔RNA
What key piece of evidence indicates that DNA, rather than protein, is the cellular genetic
material?
A. DNA from dead cells of a virulent strain of Streptococcus pneumoniae can turn an avirulent
strain into a virulent one.
B. Tracking radiolabeled nitrogen atoms within the phage T2 showed that only these atoms,
present in DNA but absent from proteins, entered a host bacterium during infection
C. There are far more variants of amino acids than nucleic acids.
D. Proteins can be found in chromosomes - Answers✔A. DNA from dead cells of a virulent
strain of Streptococcus pneumoniae can turn an avirulent strain into a virulent one.
1
, ©FYNDLAY.
Further analysis revealed DNA as the transforming agent in one of the earliest examples of
horizontal gene transfer between microbes.
What is a dimer? - Answers✔a pair of subunits
What is denaturation? - Answers✔to lose secondary and tertiary structure in a protein or nucleic
acid because of high temperature or chemical treatment.
More energy is required to break three H-bonds of a GC pair than the two H-bonds of an AT
base pair.
What is hybridization? - Answers✔To form
The annealing of a nucleic acid strand with another nucleic acid strand containing a
complementary sequence of bases. The binding of one nucleic acid strand with a complementary
strand.
What is a hairpin and when in RNA is it formed? - Answers✔-a region that loops back and forms
a "hair pin" structure.
-Form when complementary nucleotide sequences within the primary RNA sequence bends back
and hybridizes.
What is the nucleoid region? - Answers✔The looped coils of bacterial chromosomes
What are topoisomerases? - Answers✔-regulate super coils
An enzyme that can change the supercoiling of DNA
-helps maintain proper DNA supercoiling levels.
What are the two types of topoisomerases? - Answers✔Type I and Type II
Type I: are typically single proteins that cleave only one strand of a double helix
-relieve or unwind supercoils, the enzyme passes the intact strand through the break and re-ligate
(reconnect) the strand, reintroducing a helical turn.
Type II: have multiple subunits that cleave both strands of a DNA molecule.
-DNA gyrase introduce negative supercoils in DNA which is important during DNA replication
2
MCB4403 - Chp 7 Exam Questions And
Answers 100% Verified.
7.1 Discuss the evidence that led researchers to identify DNA as the genetic material of cellular
organisms. - Answers✔- Oswald Avery, and colleagues discovered that they could kill a mouse
that had live but harmless (avirulent) streptococcus pneumonia, plus dead cells from a virulent
strain of bacteria.
- the transforming agent is DNA.
-also coincidentally discovered the first of several mechanisms of horizontal gene transfer
between microbes.
What is transformation? - Answers✔The internalization of free DNA from the environment into
bacterial cells.
What do viruses such as influenza and SARS-CoV-2 use for their genetic material? -
Answers✔RNA
What key piece of evidence indicates that DNA, rather than protein, is the cellular genetic
material?
A. DNA from dead cells of a virulent strain of Streptococcus pneumoniae can turn an avirulent
strain into a virulent one.
B. Tracking radiolabeled nitrogen atoms within the phage T2 showed that only these atoms,
present in DNA but absent from proteins, entered a host bacterium during infection
C. There are far more variants of amino acids than nucleic acids.
D. Proteins can be found in chromosomes - Answers✔A. DNA from dead cells of a virulent
strain of Streptococcus pneumoniae can turn an avirulent strain into a virulent one.
1
, ©FYNDLAY.
Further analysis revealed DNA as the transforming agent in one of the earliest examples of
horizontal gene transfer between microbes.
What is a dimer? - Answers✔a pair of subunits
What is denaturation? - Answers✔to lose secondary and tertiary structure in a protein or nucleic
acid because of high temperature or chemical treatment.
More energy is required to break three H-bonds of a GC pair than the two H-bonds of an AT
base pair.
What is hybridization? - Answers✔To form
The annealing of a nucleic acid strand with another nucleic acid strand containing a
complementary sequence of bases. The binding of one nucleic acid strand with a complementary
strand.
What is a hairpin and when in RNA is it formed? - Answers✔-a region that loops back and forms
a "hair pin" structure.
-Form when complementary nucleotide sequences within the primary RNA sequence bends back
and hybridizes.
What is the nucleoid region? - Answers✔The looped coils of bacterial chromosomes
What are topoisomerases? - Answers✔-regulate super coils
An enzyme that can change the supercoiling of DNA
-helps maintain proper DNA supercoiling levels.
What are the two types of topoisomerases? - Answers✔Type I and Type II
Type I: are typically single proteins that cleave only one strand of a double helix
-relieve or unwind supercoils, the enzyme passes the intact strand through the break and re-ligate
(reconnect) the strand, reintroducing a helical turn.
Type II: have multiple subunits that cleave both strands of a DNA molecule.
-DNA gyrase introduce negative supercoils in DNA which is important during DNA replication
2
