MIB 2603 EXAM REVISION
📘
STUDY UNIT 1 – Chapter 13: Bacterial Genome Replication
and Expression
Learning Outcomes
By the end of this learning unit you should be able to:
● B riefly describe the experiments of Griffiths, Avery and colleagues as well as Hershey and
Chase.
● Discuss the control experiments that these researchers included in their experiments to
support virulence transformation and the identification of DNA as the genetic material.
● Describe the contributions that Miescher, and Mirsky and Ris have made to our
understanding of DNA.
● Describe the central dogma and discuss the results of Hershey and Chase’s experiment
from this viewpoint.
● Draw the DNA helix taking note of the major and minor grooves.
● Explain the effect of the difference in the number of hydrogen bonds between G and C
bases compared to those between A and T bases.
● Discuss similarities and differences between the structure of DNA and that of RNA.
● Access and read the 1953 Nature article written by Crick and Watson.
● Describe the experiments involving the incorporation of radioactive label into progeny
DNA strands that were used to support the concept of semiconservative replication of
DNA.
● Discuss the consequences of DNA vs. RNA polymerase proofreading ability.
● Read the legend to figure 13.12 in Prescott (2014) describing replication activities at the
replication fork.
● Define the terms “downstream” and “upstream” in the context of DNA sequences.
● Describe the process of transcription in bacteria.
● Describe the structure and catalytic activity of DNA-dependent RNA polymerase.
● Describe bacterial promoters.
● Translate a given mRNA sequence.
● Explain the difference between a codon and an anticodon.
● Describe reading frames.
● Describe the function of tRNA.
● Describe how the ribosome interacts with macromolecules.
● Describe translation including initiation, elongation and termination.
● Describe the function of initiation, elongation and termination factors.
,Question a)
riefly describe the experiments of Griffiths, Avery and colleagues as well as Hershey and Chase.
B
Include diagrams of these experiments.
Answer:
● G
riffith (1928): Demonstrated transformation usingStreptococcus pneumoniae. Heat-killed
virulent (S) + live non-virulent (R) = mouse dies.
● A
very et al. (1944): Showed DNA is the transforming factor using DNase, RNase, and
protease.
● H
ershey & Chase (1952): Used radioactive ³²P-labeled DNA and ³⁵S-labeled protein in
bacteriophages. Only DNA entered the host cell, proving DNA is genetic material.
📌
See Prescott Figures 13.1 to 13.3 for visuals.
Question b)
iscuss the control experiments that these researchers included in their experiments to support
D
virulence transformation and the identification of DNA as the genetic material.
Answer:
● A
very’s team used specific enzymes (DNase, RNase, protease) to confirm only DNA was
responsible for transformation.
● H
ershey & Chase used isotopic labeling (³²P for DNA, ³⁵S for protein) to track which
molecule entered the bacterial cell.
Question c)
ey into Google the names of the following researchers: Miescher (1878) as well as Mirsky and
K
Ris (1949). Then describe the contributions that these researchers have made to our
understanding of DNA.
,Answer:
● M
iescher (1878): Discovered nuclein (DNA) in the nuclei of white blood cells, identifying
DNA as a distinct molecule.
● M
irsky and Ris (1949): Demonstrated that DNA content is constant in somatic cells and
varies between species, supporting DNA’s role as the genetic material.
Question d)
ater in this learning unit, I will describe a flow of genetic information from DNA to RNA to protein.
L
In your own words, describe the central dogma and discuss the results of Hershey and Chase’s
experiment from this viewpoint.
nswer:
A
The central dogma describes the flow of genetic information: DNA → RNA → Protein. Hershey
and Chase confirmed that DNA—not protein—enters the host and directs viral replication,
reinforcing DNA’s central role in this process.
Question a)
Draw the DNA helix taking note of the major and minor grooves.
nswer:
A
The DNA double helix is right-handed, with two grooves:
● Major groove: Wide; allows protein binding
● M
inor groove: Narrow; less accessible
These grooves are essential for regulatory protein-DNA interactions.
Question b)
xplain the effect of the difference in the number of hydrogen bonds between G and C bases
E
compared to those between A and T bases.
, Answer:
● G-C pairs have 3 hydrogen bonds
● A
-T pairs have 2 hydrogen bonds
G-C rich DNA is more stable and requires more energy to denature due to the extra bond.
Question c)
Discuss similarities and differences between the structure of DNA and that of RNA.
Answer:
Feature DNA RNA
Sugar Deoxyribose Ribose
Bases A, T, G, C A, U, G, C
Strands Double-stranded Single-stranded
Stability High Less stable
Function Long-term storage P
rotein synthesis, regulation,
catalysis
Question d)
Access and read the 1953 Nature article written by Crick and Watson (Nature 171, 737-738).
nswer:
A
Watson and Crick described the double helix model: two antiparallel DNA strands held together
by specific base pairing (A-T, G-C). This structure explained replication, mutation, and genetic
coding.
Question a)
se Google to access details of the experiment of Meselson and Stahl (1958) and Cairns (1963).
U
Describe these experiments involving the incorporation of radioactive label into progeny DNA
strands that were used to support the concept of semiconservative replication of DNA.
📘
STUDY UNIT 1 – Chapter 13: Bacterial Genome Replication
and Expression
Learning Outcomes
By the end of this learning unit you should be able to:
● B riefly describe the experiments of Griffiths, Avery and colleagues as well as Hershey and
Chase.
● Discuss the control experiments that these researchers included in their experiments to
support virulence transformation and the identification of DNA as the genetic material.
● Describe the contributions that Miescher, and Mirsky and Ris have made to our
understanding of DNA.
● Describe the central dogma and discuss the results of Hershey and Chase’s experiment
from this viewpoint.
● Draw the DNA helix taking note of the major and minor grooves.
● Explain the effect of the difference in the number of hydrogen bonds between G and C
bases compared to those between A and T bases.
● Discuss similarities and differences between the structure of DNA and that of RNA.
● Access and read the 1953 Nature article written by Crick and Watson.
● Describe the experiments involving the incorporation of radioactive label into progeny
DNA strands that were used to support the concept of semiconservative replication of
DNA.
● Discuss the consequences of DNA vs. RNA polymerase proofreading ability.
● Read the legend to figure 13.12 in Prescott (2014) describing replication activities at the
replication fork.
● Define the terms “downstream” and “upstream” in the context of DNA sequences.
● Describe the process of transcription in bacteria.
● Describe the structure and catalytic activity of DNA-dependent RNA polymerase.
● Describe bacterial promoters.
● Translate a given mRNA sequence.
● Explain the difference between a codon and an anticodon.
● Describe reading frames.
● Describe the function of tRNA.
● Describe how the ribosome interacts with macromolecules.
● Describe translation including initiation, elongation and termination.
● Describe the function of initiation, elongation and termination factors.
,Question a)
riefly describe the experiments of Griffiths, Avery and colleagues as well as Hershey and Chase.
B
Include diagrams of these experiments.
Answer:
● G
riffith (1928): Demonstrated transformation usingStreptococcus pneumoniae. Heat-killed
virulent (S) + live non-virulent (R) = mouse dies.
● A
very et al. (1944): Showed DNA is the transforming factor using DNase, RNase, and
protease.
● H
ershey & Chase (1952): Used radioactive ³²P-labeled DNA and ³⁵S-labeled protein in
bacteriophages. Only DNA entered the host cell, proving DNA is genetic material.
📌
See Prescott Figures 13.1 to 13.3 for visuals.
Question b)
iscuss the control experiments that these researchers included in their experiments to support
D
virulence transformation and the identification of DNA as the genetic material.
Answer:
● A
very’s team used specific enzymes (DNase, RNase, protease) to confirm only DNA was
responsible for transformation.
● H
ershey & Chase used isotopic labeling (³²P for DNA, ³⁵S for protein) to track which
molecule entered the bacterial cell.
Question c)
ey into Google the names of the following researchers: Miescher (1878) as well as Mirsky and
K
Ris (1949). Then describe the contributions that these researchers have made to our
understanding of DNA.
,Answer:
● M
iescher (1878): Discovered nuclein (DNA) in the nuclei of white blood cells, identifying
DNA as a distinct molecule.
● M
irsky and Ris (1949): Demonstrated that DNA content is constant in somatic cells and
varies between species, supporting DNA’s role as the genetic material.
Question d)
ater in this learning unit, I will describe a flow of genetic information from DNA to RNA to protein.
L
In your own words, describe the central dogma and discuss the results of Hershey and Chase’s
experiment from this viewpoint.
nswer:
A
The central dogma describes the flow of genetic information: DNA → RNA → Protein. Hershey
and Chase confirmed that DNA—not protein—enters the host and directs viral replication,
reinforcing DNA’s central role in this process.
Question a)
Draw the DNA helix taking note of the major and minor grooves.
nswer:
A
The DNA double helix is right-handed, with two grooves:
● Major groove: Wide; allows protein binding
● M
inor groove: Narrow; less accessible
These grooves are essential for regulatory protein-DNA interactions.
Question b)
xplain the effect of the difference in the number of hydrogen bonds between G and C bases
E
compared to those between A and T bases.
, Answer:
● G-C pairs have 3 hydrogen bonds
● A
-T pairs have 2 hydrogen bonds
G-C rich DNA is more stable and requires more energy to denature due to the extra bond.
Question c)
Discuss similarities and differences between the structure of DNA and that of RNA.
Answer:
Feature DNA RNA
Sugar Deoxyribose Ribose
Bases A, T, G, C A, U, G, C
Strands Double-stranded Single-stranded
Stability High Less stable
Function Long-term storage P
rotein synthesis, regulation,
catalysis
Question d)
Access and read the 1953 Nature article written by Crick and Watson (Nature 171, 737-738).
nswer:
A
Watson and Crick described the double helix model: two antiparallel DNA strands held together
by specific base pairing (A-T, G-C). This structure explained replication, mutation, and genetic
coding.
Question a)
se Google to access details of the experiment of Meselson and Stahl (1958) and Cairns (1963).
U
Describe these experiments involving the incorporation of radioactive label into progeny DNA
strands that were used to support the concept of semiconservative replication of DNA.
