ALL 18 CHAPTERS COVERED
, Introduction to the Study of Cell and Molecular
Biology
CASE STUDY: Will antibiotics cure the common cold?
Picture the scene: it’s winter, your head aches, your sinuses are clogged, the coughing and
sneezing won’t stop. You’ve got a cold (or maybe even the flu). Do you wait it out at home? Or go
to your doctor or the medical clinic on campus? Maybe they can give you some antibiotics to clear
it up…
Colds, the most frequently transmitted infectious diseases in humans, are primarily caused by
a group of viruses known as rhinoviruses (from Greek and Latin words for “nose poisons”). Viruses
are non-cellular infectious agents that co-opt our cellular machinery to reproduce. The
physiological response to a rhinovirus infection involves activation of the immune system, which
leads to many symptoms we associate with the “common cold.” But since these reactions may not
be specific to the pathogen, it can be hard to know whether rhinovirus or other viruses such as
adenovirus or influenza are the culprit. Bacteria, while not the direct cause of cold symptoms, can
cause secondary infections that occur during or after the onset of a cold.
Questions:
1. Penicillin is an antibiotic that acts by inhibiting the formation of peptidoglycan cross-links
in a cell wall. Based on what you know about the nature of viruses and bacteria, will
penicillin effectively kill the rhinovirus?
2. People talk about catching a cold by touching surfaces that have been touched by
someone else with a cold, such as a door handle or faucet knob. Is this because viruses
can colonize and grow on these surfaces?
3. After entering cells, viruses use the host cell machinery to transcribe their viral DNA into
RNA or make new copies of their RNA, which will then be translated into proteins that
are needed for virus function and replication. There has been a lot of interest and some
progress in the development of anti-viral drugs that act to halt the viral replication cycle.
Do you think it would effective to target a drug to cellular RNA polymerase to halt viral
replication? Why or Why not?
,Where can I learn more?
1. Palmenberg AC, Spiro D, Kuzmickas R, et al. Sequencing and analyses of all known human
rhinovirus genomes reveal structure and evolution. Science. 2009;324(5923):55–59.
doi:10.1126/science.1165557
2. Common Colds: Protect Yourself and Others [Internet]. Centers for Disease Control and
Prevention; [updated 2019 Feb 11]. Available from:
https://www.cdc.gov/features/rhinoviruses/index.html
, The Chemical Basis of Life
CASE STUDY: Defects in Hemoglobin Structure and Function
Hemoglobin is the major oxygen carrier that is used to deliver oxygen to our tissues. It is a
heterotetrameric protein that is composed of two alpha subunits and two beta subunits. Each subunit
has the ability to bind and release oxygen, and its ability to do so is influenced by the structure of the
other subunits. Defects in hemoglobin structure or synthesis are collectively termed
hemoglobinopathies. This group of diseases results from defects in the synthesis of one of the
hemoglobin chains or in defects in the structure of the hemoglobin molecule itself. Patients with
defective hemoglobin have characteristic anemia, which leads to pallor, fatigue, and shortness of
breath. Other clinical manifestations include reticulocytosis (elevation of the number of young red
blood cells), splenomegaly (enlarged spleen), and urobilinuria (excess urobilins, which are breakdown
products of hemoglobin, in the urine).
Sickle Cell Anemia is a specific type of hemoglobinopathy caused by mutation of a single glutamic
acid residue on the surface of hemoglobin to a valine, which results in a change in the surface properties
of hemoglobin. This mutant hemoglobin is referred to as HbS. Presence of HbS causes protein
aggregation under conditions of deoxygenation. The protein aggregates lead to malformed red blood
cells that inhibit capillary flow.
Questions:
1. The mutation in hemoglobin is a change from a glutamic acid to a valine. What are the chemical
features of these two amino acids that may result in the defects caused by HbS?
2. According to the principles of the hydrophobic effect, where should glutamic acid and valine
normally be found in proteins?
3. How then do you think that the mutated valine residue can contribute to the aggregation of
hemoglobin molecules in HbS?
, Introduction to the Study of Cell and Molecular
Biology
CASE STUDY: Will antibiotics cure the common cold?
Picture the scene: it’s winter, your head aches, your sinuses are clogged, the coughing and
sneezing won’t stop. You’ve got a cold (or maybe even the flu). Do you wait it out at home? Or go
to your doctor or the medical clinic on campus? Maybe they can give you some antibiotics to clear
it up…
Colds, the most frequently transmitted infectious diseases in humans, are primarily caused by
a group of viruses known as rhinoviruses (from Greek and Latin words for “nose poisons”). Viruses
are non-cellular infectious agents that co-opt our cellular machinery to reproduce. The
physiological response to a rhinovirus infection involves activation of the immune system, which
leads to many symptoms we associate with the “common cold.” But since these reactions may not
be specific to the pathogen, it can be hard to know whether rhinovirus or other viruses such as
adenovirus or influenza are the culprit. Bacteria, while not the direct cause of cold symptoms, can
cause secondary infections that occur during or after the onset of a cold.
Questions:
1. Penicillin is an antibiotic that acts by inhibiting the formation of peptidoglycan cross-links
in a cell wall. Based on what you know about the nature of viruses and bacteria, will
penicillin effectively kill the rhinovirus?
2. People talk about catching a cold by touching surfaces that have been touched by
someone else with a cold, such as a door handle or faucet knob. Is this because viruses
can colonize and grow on these surfaces?
3. After entering cells, viruses use the host cell machinery to transcribe their viral DNA into
RNA or make new copies of their RNA, which will then be translated into proteins that
are needed for virus function and replication. There has been a lot of interest and some
progress in the development of anti-viral drugs that act to halt the viral replication cycle.
Do you think it would effective to target a drug to cellular RNA polymerase to halt viral
replication? Why or Why not?
,Where can I learn more?
1. Palmenberg AC, Spiro D, Kuzmickas R, et al. Sequencing and analyses of all known human
rhinovirus genomes reveal structure and evolution. Science. 2009;324(5923):55–59.
doi:10.1126/science.1165557
2. Common Colds: Protect Yourself and Others [Internet]. Centers for Disease Control and
Prevention; [updated 2019 Feb 11]. Available from:
https://www.cdc.gov/features/rhinoviruses/index.html
, The Chemical Basis of Life
CASE STUDY: Defects in Hemoglobin Structure and Function
Hemoglobin is the major oxygen carrier that is used to deliver oxygen to our tissues. It is a
heterotetrameric protein that is composed of two alpha subunits and two beta subunits. Each subunit
has the ability to bind and release oxygen, and its ability to do so is influenced by the structure of the
other subunits. Defects in hemoglobin structure or synthesis are collectively termed
hemoglobinopathies. This group of diseases results from defects in the synthesis of one of the
hemoglobin chains or in defects in the structure of the hemoglobin molecule itself. Patients with
defective hemoglobin have characteristic anemia, which leads to pallor, fatigue, and shortness of
breath. Other clinical manifestations include reticulocytosis (elevation of the number of young red
blood cells), splenomegaly (enlarged spleen), and urobilinuria (excess urobilins, which are breakdown
products of hemoglobin, in the urine).
Sickle Cell Anemia is a specific type of hemoglobinopathy caused by mutation of a single glutamic
acid residue on the surface of hemoglobin to a valine, which results in a change in the surface properties
of hemoglobin. This mutant hemoglobin is referred to as HbS. Presence of HbS causes protein
aggregation under conditions of deoxygenation. The protein aggregates lead to malformed red blood
cells that inhibit capillary flow.
Questions:
1. The mutation in hemoglobin is a change from a glutamic acid to a valine. What are the chemical
features of these two amino acids that may result in the defects caused by HbS?
2. According to the principles of the hydrophobic effect, where should glutamic acid and valine
normally be found in proteins?
3. How then do you think that the mutated valine residue can contribute to the aggregation of
hemoglobin molecules in HbS?
