BIOL 4310 Cell Microbiology 2026 Exam 1 Study Guide with
Complete Solutions.
P1: What are the essential features of evolving systems? correct answers 1. Must be able to
replicate
2. Must have a source of diversity (cannot replicate into the same thing; there will be no
evolution)
3. Must be a selective mechanism that allows certain variants to thrive, at least in that particular
environment.
P3: Why microbial diseases cause harm to human body? correct answers Virulence occurs in two
ways, both of which require the bacteria to enter the red, potentially symptomatic site or state:
*Direct damage to the host tissue is caused by the replication of the bacteria and/or the
production of specific products (toxins), or
*Indirect damage to the host occurs through an inappropriate or over-response of the immune
system.
P3: What are the virulence factors? correct answers Bacterial virulence factors can be divided
into several groups on the basis of the mechanism of virulence and function (BCMPS):
**Membrane proteins, which play roles in adhesion, colonization, and invasions, promote
adherence to host cell surfaces, are responsible for resistance to antibiotics, and promote
intercellular communication.
**Polysaccharide capsules that surround the bacterial cell and have anti- phagocytic properties.
**Secretory proteins, such as a toxin, which can modify the host cell environment and are
responsible for some host cell-bacteria interactions. Bacterial pathogens use distinct secretion
systems, most commonly types I-IV, to transport protein toxins from their cytoplasm into the
host or extracellular matrix. Autotransporters (ATs) are virulence proteins translocated by a
variety of pathogenic Gram-negative bacteria across the cell envelope to the cell surface or
extracellular environment. ATs comprise a family of proteins collectively secreted by the type V
pathway.
**Cell wall and outer membrane components, such as lipopolysaccharide (LPS or endotoxin)
and lipoteichoic acids. Gram-positive bacteria are naturally surrounded by a thick cell wall that
has a low permeability to the surrounding environment, while in Gram-negative bacteria the
major outer membrane glycolipid, LPS, can protect against complement-mediated lysis. LPS
activates the host complement pathway and is a potent inducer of inflammation.
**Other virulence factors, such as biofilm forming proteins and siderophores. Some bacteria
form biofilm, such as Pseudomonas aeruginosa, Mycobacterium, Streptococcus pneumoniae, and
Staphylococcus aureus. Biofilm formation confers a selective advantage for persistence under
environmental conditions and for resistance to antimicrobial agents and also facilitates
colonization in the host by the
P2: What are the properties of pathogenic bacteria that underlie the means by which they cause
diseases? correct answers The ability to invade tissues and produce toxins.
P2: How do bacteria evolve to be pathogens? correct answers Mechanisms that contribute to
bacterial genome evolution:
, **Gene acquisition by horizontal gene transfer (HGT)
**Genome reduction by DNA deletions
**Genetic rearrangements
**Point mutations
P2: What is a pathogenicity island? correct answers **Pathogenicity is generally conferred
through the inheritance of blocks of genes.
**Virulence cassettes; the second class of virulence genes that specifies traits that are unique to
pathogens; acquired by HGT.
P2: What are the mobile genetic elements? correct answers *Mediate the transfer of DNA within
and between species
**Include phages, virulence plasmids, pathogenicity islands, transposons and self-splicing
elements such as introns
**They carry segments of DNA that encode enzymes and other proteins that mediate the
movement of genetic information within genomes or between bacterial cells
P1: Can a microbe go extinct if it co-evolves within a host? correct answers No, because
essentially, a microbe needs the host to survive. In parasitism, the host is negatively affected,
however it does not go extinct.
P1: What is horizontal gene transfer? correct answers **Gene transfer between species (not via
parents)
**The transport of genetic material within and across species - is common among bacteria, but
its effect on population diversity during ecological differentiation remains controversial.
P2: What are the mechanisms for bacteria to acquire new genes? correct answers
**Transformation was the first mechanism of prokaryotic horizontal gene transfer (HGT) to be
discovered. This process involves the transfer of cellular DNA between closely related bacteria
and is mediated by chromosomally encoded proteins that are found in some naturally
transformable bacteria.
**Conjugation requires independently replicating genetic elements called conjugative plasmids,
or chromosomally INTEGRATED CONJUGATIVE ELEMENTS (ICEs), which include
conjugative transposons. These genetic elements encode proteins that facilitate their own transfer
and occasionally the transfer of other cellular DNA from the 'donor' plasmid- carrying cell to a
recipient cell that lacks the plasmid or ICE.
**Transduction is also a form of DNA transfer that is mediated by independently replicating
bacterial viruses called bacteriophages (or phages). At low frequency, bacteriophages can
accidentally package segments of host DNA in their capsid and can inject this DNA into a new
host, in which it can recombine with the cellular chromosome and be inherited. Intracellular
movement of DNA is a property of promiscuously recombining loci that are generically called
transposons, which randomly recombine or 'jump' between replicons. As transposons can 'hop'
into phages or plasmids, they can also be transferred with them into other cells.
Complete Solutions.
P1: What are the essential features of evolving systems? correct answers 1. Must be able to
replicate
2. Must have a source of diversity (cannot replicate into the same thing; there will be no
evolution)
3. Must be a selective mechanism that allows certain variants to thrive, at least in that particular
environment.
P3: Why microbial diseases cause harm to human body? correct answers Virulence occurs in two
ways, both of which require the bacteria to enter the red, potentially symptomatic site or state:
*Direct damage to the host tissue is caused by the replication of the bacteria and/or the
production of specific products (toxins), or
*Indirect damage to the host occurs through an inappropriate or over-response of the immune
system.
P3: What are the virulence factors? correct answers Bacterial virulence factors can be divided
into several groups on the basis of the mechanism of virulence and function (BCMPS):
**Membrane proteins, which play roles in adhesion, colonization, and invasions, promote
adherence to host cell surfaces, are responsible for resistance to antibiotics, and promote
intercellular communication.
**Polysaccharide capsules that surround the bacterial cell and have anti- phagocytic properties.
**Secretory proteins, such as a toxin, which can modify the host cell environment and are
responsible for some host cell-bacteria interactions. Bacterial pathogens use distinct secretion
systems, most commonly types I-IV, to transport protein toxins from their cytoplasm into the
host or extracellular matrix. Autotransporters (ATs) are virulence proteins translocated by a
variety of pathogenic Gram-negative bacteria across the cell envelope to the cell surface or
extracellular environment. ATs comprise a family of proteins collectively secreted by the type V
pathway.
**Cell wall and outer membrane components, such as lipopolysaccharide (LPS or endotoxin)
and lipoteichoic acids. Gram-positive bacteria are naturally surrounded by a thick cell wall that
has a low permeability to the surrounding environment, while in Gram-negative bacteria the
major outer membrane glycolipid, LPS, can protect against complement-mediated lysis. LPS
activates the host complement pathway and is a potent inducer of inflammation.
**Other virulence factors, such as biofilm forming proteins and siderophores. Some bacteria
form biofilm, such as Pseudomonas aeruginosa, Mycobacterium, Streptococcus pneumoniae, and
Staphylococcus aureus. Biofilm formation confers a selective advantage for persistence under
environmental conditions and for resistance to antimicrobial agents and also facilitates
colonization in the host by the
P2: What are the properties of pathogenic bacteria that underlie the means by which they cause
diseases? correct answers The ability to invade tissues and produce toxins.
P2: How do bacteria evolve to be pathogens? correct answers Mechanisms that contribute to
bacterial genome evolution:
, **Gene acquisition by horizontal gene transfer (HGT)
**Genome reduction by DNA deletions
**Genetic rearrangements
**Point mutations
P2: What is a pathogenicity island? correct answers **Pathogenicity is generally conferred
through the inheritance of blocks of genes.
**Virulence cassettes; the second class of virulence genes that specifies traits that are unique to
pathogens; acquired by HGT.
P2: What are the mobile genetic elements? correct answers *Mediate the transfer of DNA within
and between species
**Include phages, virulence plasmids, pathogenicity islands, transposons and self-splicing
elements such as introns
**They carry segments of DNA that encode enzymes and other proteins that mediate the
movement of genetic information within genomes or between bacterial cells
P1: Can a microbe go extinct if it co-evolves within a host? correct answers No, because
essentially, a microbe needs the host to survive. In parasitism, the host is negatively affected,
however it does not go extinct.
P1: What is horizontal gene transfer? correct answers **Gene transfer between species (not via
parents)
**The transport of genetic material within and across species - is common among bacteria, but
its effect on population diversity during ecological differentiation remains controversial.
P2: What are the mechanisms for bacteria to acquire new genes? correct answers
**Transformation was the first mechanism of prokaryotic horizontal gene transfer (HGT) to be
discovered. This process involves the transfer of cellular DNA between closely related bacteria
and is mediated by chromosomally encoded proteins that are found in some naturally
transformable bacteria.
**Conjugation requires independently replicating genetic elements called conjugative plasmids,
or chromosomally INTEGRATED CONJUGATIVE ELEMENTS (ICEs), which include
conjugative transposons. These genetic elements encode proteins that facilitate their own transfer
and occasionally the transfer of other cellular DNA from the 'donor' plasmid- carrying cell to a
recipient cell that lacks the plasmid or ICE.
**Transduction is also a form of DNA transfer that is mediated by independently replicating
bacterial viruses called bacteriophages (or phages). At low frequency, bacteriophages can
accidentally package segments of host DNA in their capsid and can inject this DNA into a new
host, in which it can recombine with the cellular chromosome and be inherited. Intracellular
movement of DNA is a property of promiscuously recombining loci that are generically called
transposons, which randomly recombine or 'jump' between replicons. As transposons can 'hop'
into phages or plasmids, they can also be transferred with them into other cells.
