Normal (resident) flora, indigenous flora, microbiota
Microbes that engage in mutual or commensal associations
Infection
A condition in which pathogenic microbes penetrate host defenses,
enter tissues, and multiply
Pathogen
Infectious agent
Infectious disease
An infection that causes damage or disruption to tissues and organs
Contact, Colonization, Invasion, and Infection
Refer to slide 3 in powerpoint
Resident Flora
Most areas of the body in contact with the outside environment harbor
resident microbes
Internal organs, tissues, and fluids are microbe-free
Transients
Microbes that occupy the body for only short periods
Residents
Microbes that become established
Sites that harbor normal resident microbes include:
Skin and its contiguous mucous membranes
URT
GI tract
Outer opening of urethra
External genitalia
Vagina
External ear canal
External eye (lids, lash follicles)
Initial colonization of the newborn
Uterus and contents are normally sterile and remain so until just
before birth. Breaking of fetal membrane exposes the infant; all
subsequent handling and feeding continue to introduce what will be
normal flora.
Normal flora is essential...
to the health of humans
Flora create an environment that may prevent�
infections and can enhance host defenses
What may alter flora?
Antibiotics, dietary changes, and disease
Probiotics
Introducing known microbes back into the body
Oh Once One Takes The Anatomy Final, Very Good Vacations Are Heavenly... 12 nerves
Olfacatory,optic, oculomotor, trochlear, trigeminal, abducens, fcial Vestibulocochlear, Glassopharyngeal, bagus, accerssory, hyoglossal
Optic nerve
*Arise from retinas: really a brain tract
*pass through optic canal, converge, and partially cross over at Optic Chiasma
*optic tracts continue to thalamus
*optic radiation fibers run to occipital cortex
Oculomotor nerve:
*fibers extend from ventral midbrain through superior orbital fissures to four of six extrinsic eye muscles.
*function in raising eyelid, directing eyeball, constricting iris, and controlling lens shape.
Abducens nerves:
*Fibers from inferior pons enter orbits via superior orbital fissures
*primarily a motor, innervating lateral rectus muscle
Facial Nerve:
*fibers from pons travel through internal acoustic meatuses and emerge through stylomastoid foramina to lateral aspect of face.
*cheif motor nerves of face with five major
*Motor functions include facial expressions, parasympathetic impluses to lacrimal and salivary glands.
*sensory functions(taste) from anterior two thirds of tongue.
Glossopharyngeal nerves:
*Fibers from medulla leave skull via jugular foramen and run to throat
* motor functions: innervate part of tongue and pharynx for swallowing and provide parasympathetic fibers to parotid salivary glands
*Sensory functions: fibers conduct taste and general sensory impulses from pharynx and posterior tongue, and impulses from carotid chemoreceptors and baroreceptors.
Vagus nerves:
*only cranial nerves that extend beyond head and neck region
*fibers from medulla exit skull via jugular foramen
*most motor: fibers are parasympathetic fibers that help regulate activities of heart, lungs and abdominal viscera
*sensory fibers carry impluses from thoracic and abdominal viscera, baroreceptors, chemoreceptors, and taste buds of posterior tongue and pharynx
8 pairs of cervical nerves
C1-C8
12 pairs of thoracic nerves
T1- T12
5 pairs of lumbar nerves
L1-L5
5 pairs of sacral nerves
S1-S5
1 pair of tiny coccygeal nerves
Co
Ventral roots (front)
Contains motor (efferent) fibers from ventral horn motor neurons that innervate skeletal muscles
Dorsal roots (back)
Contain sensory (afferent) fibers from sensory neurons in dorsal root ganglia that conduct impulses from peripheral receptors
Hilton's Law
any nerve serving a muscle that produces movement at a joint also innervates that joint and skin over that joint.
(example: knee joint when extended the quads are moving, when its contradicted the hamstrings are moving)
receptor
site of stimulus action
sensory neuron
transmits afferent impulses to CNS
intergration center
Either monosynaptic or polysynaptic region within CNS
motor neurons:
conducts efferent impulses from integration center to effector organ
Effector:
muscles fiber or gland cell that responds to efferent impulses by contracting or secreting
Describe the features of viruses that distinguish them from living cells.
Bacteriophage - A virus that infects bacteria
Burst size - Number of newly formed virus particles
released from a single cell following virus replication.
Carrier cells - Cells that are capable of releasing
virus particles without being killed by the virus.
Latent State - The state of a phage when its DNA is
integrated into the genome of the host.
Lysogen - A bacterium that carries phage DNA
(the prophage) integrated into its genome.
Lysogenic conversion - The change in properties of a
bacterium as a result of carrying a prophage. The phage DNA codes for
the new properties.
Maturation - The stage in viral replication in which
the various components of the virion assemble to form a whole virion.
Productive infection - Virus infection in which more
virus particles are produced as a result of infection.
Prophage - Phage DNA that is integrated into the
genome of a host.
Temperate phage - A phage that has the ability to
integrate its DNA into the chromosome of the host.
Virion - A virus in its inert extracellular form.
Draw the most common shape of a phage particle and label its parts.
A complex phage have an isometric head with a long tail. The
nucleocapsid is a viral capsid encloses nucleic acid tightly within
its protein coat. In tailless isometric viruses, attachment proteins
or spikes project from the capsid and are involved in attaching the
virus to the host cell.
List four features of viruses that distinguish them from free-living cells.
Multiplication: Viruses multiply only within cells;
outside the cell they are metabolically inert; protein coat and
nucleic acid separate prior to multiplication.
Nucleic acid content: Contain either DNA or RNA, but
never both.
Enzyme content: contain very few, if any, enzymes.
Internal components: Lack ribosomes and enzymes for
harvesting energy.
List three functions that all viruses must perform.
(1) make the viral protein coat, (2) assure replication of viral
nucleic acid, (3) move the virus into and out of the host cell.
List the steps in the replication process of a lytic phage and the
major feature of each step.
Step 1: Attachment - protein tail
fibers on the tail of the phage absorb to specific receptors
on the cell wall.
Step 2: Penetration - the DNA passes through the
open channel of the tail and is injected into the
cell. The phage coat remains on the outside.
Step 3: Transcription - the phage DNA is
transcribed. Some is transcribed early in infection
and other regions are trasncribed later. The mRNA is then
translated into phage proteins.
Step 4: Replication of Phage DNA and Synthesis of
Proteins - the phage DNA and proteins replicate independently
of one another. A phage enzyme degrades the bacterial chromosome so
that only phage proteins are synthesized.
Step 5: Assembly
(maturation) - This is a highly
complex and ordered series of processes, some are catalyzed by
enzymes, others not. The net result is the assembly of the phage
components into a complete virus particle.
Step 6: Release - a phage-encoded
lysozyme lyses the cells resulting in the release of many virus
particles per infected cell. This is the burst size.
List the steps in the replication of phage in a latent stage and
describe how latency is maintained.
The temperate phage can enter either go through a lytic cycle similar
to T4 or integrate its DNA into a specific site in the bacterial chromosome.
Integration of phage DNA into the bacterial
chromosome as a prophage occurs by means of site-specific recombination.
The prophage is maintained in an integrated state
because a repressor prevents expression of genes coding for an enzyme
that excises the prophage from the chromosome.
Lysogens, the bacteria carrying prophage, are immune
to the same phage whose DNA they carry.
Prophage often code for proteins that confer unique properties on
the bacteria, a process called lysogenic conversion.
How does T4 phage prevent the infected bacterium from synthesizing
bacterial proteins?
Infections are blocked because the repressor binds to the operator in
the phage DNA as it enters the cell and inhibits its replication.
Consequently, the cell is immune to infection by the same phage but
not to infection by other phages, to whose DNA the repressor cannot
bind. In this way the phage protects its turf from closely related phages.
What are the two ways that phage can replicate in harmony with their host?
...
Describe the diferences between generalized and specialized transduction.
Generalized transduction involves the transfer of any
piece of the bacterial chromosome from one cell to another cell of the
same species.
Phage genes together with bacterial DNA replicate and the phage DNA
codes for the phage coat protein. The coat surrounds the bacterial and
phage DNA, and following lysis, the bacterial DNA is transferred to
other bacteria in the environment.
Generalized transduction can be carried out by virulent and
temperate phages.
Specialized Transduction involves the transfer of
specific genes and is carried out only by temperate phages. Lambda is
a well-studied specialized transducing phage.
Only genes located near the ste at which the temperate phage
integrates its DNA are transduced. Bacterial genes may remain attached
to the phage DNA when the phage DNA excises from the bacterial chromosome.
What is meant by a defective phage?
...
List three mechanisms that reduce infection by phage.
...
Describe the activities of the two enzymes in the restriction
modification system.
...
What kind of enzymatic activity does the modification system have?
...
Infection
Occurs when pathogens enter and multiply in body tissues
Infectious disease
Caused by microorganisms or their products
Normal flora
Resident, indigenous, normal microflora
Endogenous infectious agents
Arise from microbes that are the patient's own normal flora
The human body typically begins to be colonized by its normal flora...
During, and immediately after birth
Resident flora are found...
On/in the skin, mouth, nasal passages, and large intestine
Resident flora of the skin
Staphlococcus, Corynebacterium, Micrococcus, Mycobacterium
Resident flora of intestines
Bacteroides
Resident flora of mouth, large intestine, and from puberty to
menopause, the vagina
Lactobacillus
Most common resident flora of mouth surfaces
Streptococcus
Resident flora that produces beneficial body products, including
vitamin K and several other vitamins
Large intestine
Virulence factors
Capsules, exoenzymes, endotoxin, exotoxin
STORCH
Represents most common infections of the fetus and neonate
Examples of exoenzymes
Microbial hyaluronidase, coagulase, and streptokinase
Exotoxins
Are proteins
Enterotoxins
Are virulence factors, toxins that target the intestines, proteins, exotoxins
Fimbraie
Adherence to substrate
Capsules
Antiphagocytic factor
Leukocidins
Damage WBCs
Hemolysins
Damage RBCs
Period of invasion
Specific signs and symptoms are seen and the pathogen is at peak activity
The time from when pathogen first enters the body and begins to
multiply, until symptoms first appear
Incubation period
Prodromal Stage
Initial, brief period of early, general symptoms such as fatigue and
muscle aches
Mixed infection
Several agents established at infection site
Acute infection
Rapid onset of severe, short-lived symptoms
Local infection
Pathogen remains at or near entry site
Toxemia
Pathogen's toxins carried by the blood to target tissues
Symptom
The subjective evidence of disease sensed by the patient
Sign
The objective, measurable evidence of disease evaluated by an observer
Inflammation
Local edema, swollen lymph nodes, fever, soreness, and abscesses
Immunology
The study of frequency and distribution of a disease in a defined population
Central Nervous System (CNS)
Associated with the brain and the spinal cord
Responsible for integrating, processing, and coordinating
sensory input Responsible for integrating, processing, and
coordinating motor output It is the seat of intelligence,
memory, learning, and emotion
Peripheral Nervous System (PNS)
Associated with the tissue outside the CNS
Provides sensory information to the CNS and carries motor
commands away from the CNS Can be divided into:
Afferent division Brings sensory information to the
CNS Efferent division Carries motor commands to
muscles and glands
Afferent (PERIPHERAL)
Can be further subdivided into somatic and visceral
Somatic portion: monitors skeletal muscles and
joints
Visceral portion: monitors smooth muscles, cardiac
muscle, and other internal organs
Efferent (PERIPHERAL)
Can be further subdivided into somatic nerves and
autonomic nerves
Can be further subdivided into sympathetic and parasympathetic nerves
Somatic nerves: control skeletal muscle
contraction
Autonomic nerves: control internal organ
activities
Parasympathetic nerves Cause pupil
constriction, decrease heart rate, and tense the urinary bladder
(for example)
Sympathetic nerves Cause pupil
dilation, increase heart rate, and relax urinary bladder (for
example)
Neurons
Nerve cells that are responsible for the transfer and
processing of information in the nervous system Consist of
a soma, axon, and dendrites
Neuroglia
Supporting cells Protect the neuron
Functions of Neuroglia
Provide the framework for the neural tissue Maintain
the intercellular environment Act as phagocytes
Have the ability to reproduce
Neuroglia Cells of the CNS
Astrocytes
Have a large number of cytoplasmic processes Control
the chemical content of the interstitial environment
Maintain the blood�brain barrier
Isolate the neurons from general circulation
Neuroglia of the CNS
Oligodendrocytes
Cytoplasmic extensions contact the somas or axons
Cytoplasmic extensions tie axons together in a sheath of
myelin
Neuroglia of the CNS
Microglia
Phagocytic cells Protect the neuron by removing waste
and debris
Neuroglia of the CNS
Ependymal cells
Line the ventricles of the brain Line the central
canal of the spinal cord Monitor the CSF
(cerebrospinal fluid) composition Some
ependymal cells secrete CSF
Neuroglia of the PNS
Satellite cells
Regulate the exchange of material between the cell body and the
environment
Neuroglia of the PNS
Schwann cells
Also called neurolemmocytes Form a
myelin sheath
A nerve impulse is
the action potential of a nerve The
action potential is due to the exchange of ions
across the membrane The ability to conduct the
impulse is known as excitability
A stimulus is anything that causes an
action potential to occur The stimulus has to overcome
the threshold level of that particular
neuron The threshold level is the amount of stimuli
required to create the action potential Once an impulse
starts, it is propagated along the length of the axon
speed of nerve impulse
The �speed� of the impulse depends on: Presence of a
myelin sheath Fast impulse Lack of a myelin
sheath Slow impulse Myelinated axons with a large
diameter Fast impulse Up to 140 m/sec
Unmyelinated axons with a small diameter Slow
impulse Less than 1 m/sec
Organization in the CNS
Gray matter organization
Neural cortex Gray matter on the surface of the
brain
Nuclei
Neuron cell bodies in the interior of the CNS
White matter organization
Bundles of CNS axons that form ascending and descending
columns
Organization in the PNS
Gray matter
Ganglia are collections of neuron cell bodies in the PNS
White matter
Bundles of axons in the PNS
Which of the following statements concerning viruses is FALSE?
A) Viruses never contain both DNA and RNA.
B) Viruses enter a cell to complete the replication they have begun extracellularly.
C) Some viruses have an outer membrane called an envelope.
D) Viral capsids can assume one of three basic shapes.
E) Tobacco mosaic virus was the first virus to be discovered and characterized.
B) Viruses enter a cell to complete the replication they have begun extracellularly.
The outermost layer of a virion fulfills which of the following
functions of the virus?
A) protection
B) recognition
C) replication
D) protection and recognition
E) recognition and replication
D) protection and recognition
During the intracellular state, a virus exists as
A) a lipid.
B) a protein.
C) a nucleic acid.
D) both a protein and a nucleic acid.
E) both a lipid and a nucleic acid.
C) a nucleic acid.
Viruses are primarily classified according to their
A) type of nucleic acid.
B) type of life cycle.
C) number of chromosomes.
D) shape.
E) size.
A) type of nucleic acid.
Host specificity of a virus is due to
A) particular genes that it shares with the infected cell.
B) the presence of an envelope.
C) differences in size between the virus and the host cell.
D) the presence or absence of a cell wall on the host cell.
E) interactions between viral and cellular surface molecules.
A) particular genes that it shares with the infected cell.
Who was the first person to demonstrate the existence of viruses?
A) Stanley
B) Rous
C) Lacks
D) Ivanowsky
E) Prusiner
D) Ivanowsky
How are fungal viruses different from viruses that infect other organisms?
A) They have no extracellular state.
B) They have only DNA for genetic material.
C) They have no capsid.
D) They have no intracellular state.
E) They cannot pass through a filter.
A) They have no extracellular state.
Which of the following infectious particles do NOT have protein in
their structure?
A) bacteriophages
B) prions
C) animal viruses
D) viroids
E) both prions and viroids
D) viroids
Which of the following would NOT be found as a component of a bacteriophage?
A) envelope
B) icosahedral capsid
C) DNA
D) tail fibers
E) base plate
A) envelope
Which of the following statements regarding virus taxonomy is true?
A) Viruses are classified on the basis of the taxonomy of their host organisms.
B) Virus classes are well established.
C) Some virus family names are derived from the name of an important
member of the family.
D) The species epithet is a Latin descriptor of the virion structure.
E) Virus classes are based on the domain of the host organism.
C) Some virus family names are derived from the name of an important
member of the family.
Which of the following statements comparing virus classification and
taxonomy of
organisms is true?
A) Both viruses and organisms are organized into classes.
B) The common names of viruses are their genus and species epithet,
as they are with organisms.
C) Both viruses and organisms are organized into domains.
D) Genus and specific epithet are used in both classification systems.
E) Only families are common to both viral classification and
organism taxonomy.
D) Genus and specific epithet are used in both classification systems.
Put the following stages of a lytic replication cycle in order, from
earliest to latest stages:
I. Synthesis
II. Assembly
III. Attachment
IV. Release
V. Entry
A) III, V, I, II, IV
B) III, II, V, I, IV
C) V, III, II, IV, I
D) I, III, V, II, IV
E) I, II, III, V, IV
A) III, V, I, II, IV
13) Which of the following is associated with the attachment of a
bacteriophage to a bacterial
cell?
A) random collisions
B) chemical attractions
C) receptor specificity
D) chemical attractions and receptor specificity
E) random collisions, chemical attractions, and receptor specificity
E) random collisions, chemical attractions, and receptor specificit
14) The enzyme lysozyme is critical for which of the stages of a
bacteriophage T4 infection
cycle?
A) entry
B) assembly
C) entry and release
D) synthesis
E) attachment
C) entry and release
The phenomenon of transduction is associated with which of the stages
of a bacteriophage
infection cycle?
A) attachment
B) assembly
C) release
D) synthesis
E) entry
B) assembly
Which of the following events occurs in the lytic cycle of
bacteriophage T4 infection but
NOT in the lysogenic cycle?
A) attachment
B) entry
C) digestion of host DNA
D) viral protein synthesis
E) both digestion of host DNA and viral proteins synthesis
C) digestion of host DNA
Why is lysogeny advantageous to a bacteriophage?
A) It speeds up the viral infection cycle.
B) The genetic material of the bacteriophage can be passed on to
future generations of cells.
C) It allows the bacteriophage to infect cells it would not normally infect.
D) It allows the bacteriophage to destroy the host cell's DNA.
E) It enables the bacteriophage to take over the cell.
B) The genetic material of the bacteriophage can be passed on to
future generations of cells.
Which of the following agents is capable of inducing conversion of a
prophage back to a
lytic phage?
A) UV light
B) X rays
C) presence of +ssRNA
D) UV light and X rays
E) UV light and +ssRNA
D) UV light and X rays
Zones of clearing in cell cultures that are the result of virus
infection are called plaques.
Sometimes "cloudy plaques" are seen on bacterial
cultures infected with bacteriophage. What
type of viral infection might cause this appearance?
A) lytic
B) lysogenic
C) prion
D) viroid
E) transducing
B) lysogenic
Which of the following is matched INCORRECTLY?
A) poliovirus � direct penetration
B) herpesvirus � endocytosis
C) adenovirus � membrane fusion
D) measles virus � membrane fusion
E) HIV � membrane fusion
C) adenovirus � membrane fusion
Reverse transcriptase is associated with which of the following?
A) dsDNA viruses
B) +ssRNA viruses
C) -ssRNA viruses
D) retroviruses
E) dsRNA viruses
D) retroviruses
The genome of which of the following types of animal virus can act
directly as mRNA?
A) retroviruses
B) +ssRNA viruses
C) -ssRNA viruses
D) ssDNA viruses
E) dsRNA viruses
B) +ssRNA viruses
Which of the following types of animal virus requires RNA-dependent
RNA transcriptase to
be replicated?
A) +ssRNA viruses
B) ssDNA viruses
C) -ssRNA viruses
D) retroviruses
E) dsDNA viruses
C) -ssRNA viruses
In contrast to most dsDNA animal viruses, the poxviruses replicate
solely in the cytoplasm of
the host cell. This fact implies that the viral genome may encode
A) reverse transcriptase.
B) a DNA polymerase.
C) RNA-dependent RNA transcriptase.
D) ribosome components.
E) reverse transcriptase and RNA-dependent RNA transcriptase.
B) a DNA polymerase.
Which of the following membranes can give rise to a viral envelope?
A) the nuclear membrane
B) the cytoplasmic membrane
C) the endoplasmic reticulum
D) the nuclear and cytoplasmic membranes
E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum
E) the nuclear and cytoplasmic membranes and the endoplasmic reticulum
The majority of cases of infant diarrhea are caused by what kind of virus?
A) dsDNA viruses
B) dsRNA viruses
C) +ssRNA viruses
D) retroviruses
E) -ssRNA viruses
B) dsRNA viruses
How is the HIV provirus different from a lambda phage prophage?
A) The HIV provirus is integrated permanently into the host cell's DNA.
B) All subsequent generations of HIV-infected cells carry the provirus.
C) All the offspring of a cell infected with a prophage will contain
the virus.
D) The HIV provirus is inactive inside the host cell.
E) Lambda phage-infected cells produce virus slowly over time.
A) The HIV provirus is integrated permanently into the host cell's DNA.
Which of the following individuals discovered prions?
A) Lacks
B) Iwanowsky
C) Prusiner
D) Stanley
E) Rous
C) Prusiner
One mechanism by which viruses may cause cancer is to interrupt the
genetic regulatory
sequences of repressor proteins. Which of the following types of
viruses is most likely to be
involved in causing cancer by this mechanism?
A) +ssRNA viruses
B) dsRNA viruses
C) -ssRNA viruses
D) retroviruses
E) +ssRNA and -ssRNA viruses
D) retroviruses
Tumors invade other organs and tissues in a process called
A) neoplasia.
B) a plaque assay.
C) latency.
D) budding.
E) metastasis.
E) metastasis.
Plaque assays are used for
A) evaluating the cancer-causing ability of a virus.
B) estimating the number of phages in a culture.
C) the study of prions.
D) cultivating viruses that cannot be grown any other way.
E) counting the number of latent phages in a cell.
B) estimating the number of phages in a culture.
Diploid cell cultures and continuous cell cultures differ in which of
the following ways?
A) longevity
B) source of cells
C) convenience of use
D) longevity and convenience of use
E) longevity and source of cells
E) longevity and source of cells
Viroids infect
A) bacteria.
B) plants.
C) fungi.
D) plants and animals.
E) all organisms.
B) plants.
How are prions different from all other known infectious agents?
A) They cannot reproduce outside a cell.
B) They act as slow viruses.
C) They cause neurological problems.
D) They can be destroyed by incineration.
E) They lack nucleic acid.
E) They lack nucleic acid.
The infectious particles of fungi have RNA genomes and lack a capsid.
They are therefore
similar to
A) bacteriophages.
B) enveloped viruses.
C) prions.
D) viroids.
E) lysogens.
D) viroids.
A lipid membrane is present
A) only in viruses.
B) in both cells and viruses.
C) only in cells.
D) only in prions.
E) in both prions and viroids.
B) in both cells and viruses.
Double-stranded DNA genomes are found
A) only in viroids.
B) only in cells.
C) only in viruses.
D) in both cells and viruses.
E) in both viruses and viroids.
D) in both cells and viruses.
Double-stranded RNA genomes can be found
A) only in cells.
B) in both cells and viruses.
C) only in viruses.
D) in prions.
E) in both prions and viruses.
C) only in viruses.
Cytoplasm is a characteristic of
A) cells only.
B) viruses only.
C) both cells and viruses.
D) viroids only.
E) both viroids and viruses.
A) cells only.
Proteins are present in
A) cells only.
B) viruses only.
C) viroids only.
D) both cells and viruses.
E) cells, viruses, and viroids.
D) both cells and viruses.
Viruses are shed slowly and steadily during
A) lytic replication.
B) budding.
C) oncogenesis.
D) persistent infection.
E) latency.
D) persistent infection.
During __________, viruses remain dormant in a cell.
A) budding
B) latency
C) lytic replication
D) persistent infection
E) oncogenesis
B) latency
Virus replication results in the death of the cell in a(n) __________ infection.
A) lytic
B) latent
C) persistent
D) oncogenic
E) both latent and persistent
A) lytic
Virus infection results in cancer in the process of
A) lytic replication.
B) budding.
C) oncogenesis.
D) persistent infection.
E) latency.
C) oncogenesis.
is a mechanism of release for enveloped viruses.
A) Lytic replication
B) Persistent infection
C) Oncogenesis
D) Latency
E) Budding
E) Budding
Viruses cause most human cancers.
FALSE
Most viruses cannot be seen by light microscopy.
TRUE
Protozoa are susceptible to viral attack.
TRUE
Many diseases of plants are caused by infectious RNA molecules
lacking capsids.
TRUE
Bacteriophages are cheaper and easier to culture than animal viruses.
TRUE
Assembly of new viruses is a process that usually requires the
direction of a variety of viral
and cellular enzymes.
FALSE
Bacteriophage release is a gradual process in which small numbers are
released at a time.
FALSE
Poxvirus is assembled in the cytoplasm of the cell instead of in the
nucleus, as is the case for
the majority of dsDNA viruses.
TRUE
Transcription of RNA from RNA does not occur in uninfected cells.
TRUE
Virus vaccines are always cultured in embryonated chicken eggs.
FALSE
The combination of a virus's protein coat and nucleic acid
core is called the __________.
Answer: nucleocapsid
Viral capsids are composed of subunits called __________.
Answer: capsomeres
A(n) __________ is a 20-sided polyhedral capsid.
Answer: icosahedron
Bacteriophages use the enzyme __________ to breach the bacterial cell wall.
Answer: lysozyme
The number of new bacteriophages released from each infected cell is
called the __________
size.
Answer: burst
The process in which viral capsids are removed within the infected
cell is called __________.
Answer: uncoating
Virus RNA that can act directly as mRNA is __________-strand RNA.
Answer: positive
RNA viruses such as HIV require the activity of reverse __________ to
become proviruses.
Answer: transcriptase
In enveloped viruses, virus-encoded __________ proteins are required
for the assembly of
the envelope around the capsid.
Answer: matrix
Genes that play a role in proper cell division but may also play a
role in some types of cancer
are called __________.
Answer: protooncogenes
A(n) __________ is a clear zone on a bacterial lawn where cells have
been killed by the
activity of a bacteriophage.
Answer: plaque
Three __________ represent the highest level of taxonomic rank used
in classifying viruses.
Answer: orders
Prions are composed of a single protein called __________. (Be sure
you use proper
capitalization.)
Answer: PrP
An animal virus that does not have an envelope is described as a(n)
__________ virion.
Answer: naked
Gloss/o
tongue
gingiv/o
gums
rect/o
rectum
sial/o
salivary
sigmoid/o
sigmoid colon
stomat/o, stom/o
mouth
ile/o
ileum
hepat/o, hepatic/o
liver
jejun/o
jejunum
lapar/o
abdominal wall
proct/o
anus, rectum
odont/o
tooth
phag/o
to eat
pharyng/o
pharynx
duoden/o
duodenum
enter-
intestine
gastr/o
stomach
pancreat/o
pancreas
pyl/o, pylor/o
pylorous
an/o
anal
append/o, appendic/o
appendix
col/o, colon/o
colon
laryng/o
larnyx
peritone/o
peritoneum
chol/e, chol/o
bile
cyst/o
bladder, sac
esophag/o
esophagus
choledoch/o
bile duct
cheil/o, chil/o
lip
bil/o
bile
cec/o
cecum
celi/o, cel/o
abdomen
cholangi/o
bile duct or hepatic duct
1) How do all viruses differ from bacteria?
A) Viruses are filterable.
B) Viruses are obligate intracellular parasites.
C) Viruses do not have any nucleic acid.
D) Viruses are not composed of cells.
E) Viruses do not reproduce.
Answer: D
2) Which of the following statements provides the most significant
support for the idea that viruses are nonliving chemicals?
A) They are not composed of cells.
B) They are filterable.
C) They cannot reproduce themselves outside a host.
D) They cause diseases similar to those caused by chemicals.
E) They are chemically simple.
Answer: C
3) Which of the following statements about viral spikes is FALSE?
A) They are composed of carbohydrate-protein complexes.
B) They are used for attachment.
C) They may cause hemagglutination.
D) They bind to receptors on the host cell surface.
E) They are found only on nonenveloped viruses.
Answer: E
4) Which of the following is NOT used as a criterion to classify viruses?
A) biochemical tests
B) morphology
C) nucleic acid
D) size
E) number of capsomeres
Answer: A
5) Which of the following is NOT utilized to culture viruses?
A) laboratory animals
B) culture media
C) embryonated eggs
D) animal cell cultures
E) bacterial cultures
Answer: B
6) Bacteriophages and animal viruses do NOT differ significantly in
which one of the following steps?
A) attachment
B) penetration
C) uncoating
D) biosynthesis
E) release
Answer: D
7) The definition of lysogeny is
A) phage DNA is incorporated into host cell DNA.
B) lysis of the host cell due to a phage.
C) the period during replication when virions are not present.
D) when the burst time takes an unusually long time.
E) attachment of a phage to a cell.
Answer: A
8) A viroid is a(n)
A) complete, infectious virus particle.
B) infectious piece of RNA without a capsid.
C) capsid without nucleic acid.
D) provirus.
E) infectious protein.
Answer: B
9) In Figure 13.1, which structure is a complex virus?
A) a B) b C) c D) d E) All
of the structures are complex viruses.
Answer: B
10) The structures illustrated in Figure 13.1 are composed of
A) DNA.
B) RNA.
C) DNA or RNA.
D) Capsomeres.
E) viroids.
Answer: D
11) A clear area against a confluent "lawn" of bacteria is
called a
A) phage.
B) pock.
C) cell lysis.
D) plaque.
E) rash.
Answer: D
12) Continuous cell lines differ from primary cell lines in that
A) viruses can be grown in continuous cell lines.
B) continuous cell lines always have to be re-isolated from animal tissues.
C) continuous cell lines are derived from primary cell lines.
D) continuous cell lines can be maintained through an indefinite
number of generations.
E) continuous cell lines are from human embryos.
Answer: D
13) Which of the following is necessary for replication of a prion?
A) DNA
B) DNA polymerase
C) lysozyme
D) PrPSc
E) RNA
Answer: D
14) A persistent infection is one in which
A) the virus remains in equilibrium with the host without causing a disease.
B) viral replication is unusually slow.
C) the disease process occurs gradually over a long period.
D) host cells are gradually lysed.
E) host cells are transformed.
Answer: C
15) Which of the following statements is FALSE?
A) A prophage is phage DNA inserted into a bacterial chromosome.
B) A prophage can "pop" out of the chromosome.
C) Prophage genes are repressed by a repressor protein coded for by
the prophage.
D) A prophage may result in new properties of the host cell.
E) The prophage makes the host cell immune to infection by other phages.
Answer: E
16) Lysogeny can result in all of the following EXCEPT
A) immunity to reinfection by the same phage.
B) acquisition of new characteristics by the host cell.
C) immunity to reinfection by any phage.
D) specialized transduction.
E) phage conversion.
Answer: C
17) Which of the following would be the first step in biosynthesis of
a virus with a - (minus) strand of RNA?
A) synthesis of DNA from an RNA template
B) synthesis of double-stranded RNA from an RNA template
C) synthesis of double-stranded RNA from a DNA template
D) transcription of mRNA from DNA
E) synthesis of DNA from a DNA template
Answer: B
18) An infectious protein is a
A) bacteriophage.
B) prion.
C) retrovirus.
D) viroid.
E) papovavirus.
Answer: B
19) An envelope is acquired during which of the following steps?
A) penetration
B) adsorption
C) uncoating
D) biosynthesis
E) release
Answer: E
20) Which of the following statements is NOT true of lysogeny?
A) It can give infected pathogens the genetic information for toxin production.
B) Prophage is inserted into the host genome.
C) Lytic cycle may follow lysogeny.
D) It is a "silent" infection; the virus does not replicate.
E) It causes lysis of host cells.
Answer: E
21) An example of a latent viral infection is
A) subacute sclerosing panencephalitis.
B) cold sores.
C) influenza.
D) smallpox.
E) mumps.
Answer: B
22) A virus's ability to infect an animal cell depends primarily upon the
A) host cell's ability to phagocytize viral particles.
B) presence of receptor sites on the cell membrane. C)
type of viral nucleic acid. D) enzymatic activity of a host
cell. E) presence of pili on the host cell wall.
Answer: B
23) Assume you have isolated an unknown virus. This virus has a
single, positive sense strand of RNA, and possesses an envelope. To
which group does it most likely belong?
A) herpesvirus
B) picornavirus
C) retrovirus
D) togavirus
E) papovavirus
Answer: D
24) The mechanism whereby an enveloped virus leaves a host cell is called
A) transduction.
B) budding.
C) abduction.
D) lysogeny.
E) penetration.
Answer: B
25) The most conclusive evidence that viruses cause cancers is
provided by
A) finding oncogenes in viruses.
B) the presence of antibodies against viruses in cancer patients.
C) cancer following injection of cell-free filtrates.
D) treating cancer with antibodies.
E) some liver cancer patients having had hepatitis.
Answer: C
26) Bacteriophages derive all of the following from the host cell EXCEPT
A) lysozyme.
B) tRNA.
C) amino acids.
D) nucleotides.
E) ATP.
Answer: A
27) Bacteriophage replication differs from animal virus replication
because only bacteriophage replication involves
A) adsorption to specific receptors.
B) assembly of viral components.
C) replication of viral nucleic acid.
D) injection of naked nucleic acid into the host cell.
E) lysis of the host cell.
Answer: D
28) Generally, in an infection caused by a DNA-containing virus, the
host animal cell supplies all of the following EXCEPT
A) RNA polymerase.
B) nucleotides.
C) DNA polymerase.
D) tRNA.
E) None of the answers are correct; all of these are supplied by the
host animal cell.
Answer: C
29) Which of the following places these items in the correct order
for DNA-virus replication?
Maturation DNA synthesis Transcription
Translation
A) 1; 2; 3; 4 B) 2; 3; 4; 1 C) 3; 4; 1;
2 D) 4; 1; 2; 3 E) 4; 3; 2; 1
Answer: B
30) A viral species is a group of viruses that
A) has the same morphology and nucleic acid.
B) has the same genetic information and ecological niche.
C) infects the same cells and cause the same disease.
D) cannot be defined.
Answer: B
31) Viruses that utilize reverse transcriptase belong to the virus
familiesA) Retroviridae and Picornaviridae.B)
Herpesviridae and Retroviridae.C) Hepadnaviridae and
Retroviridae.D) Herpesviridae and Poxviridae.E)
Rhabdoviridae and Herpesviridae.
Answer: C
32) DNA made from an RNA template will be incorporated into the virus
capsid of
A) Retroviridae.
B) Herpesviridae.
C) Hepadnaviridae.
D) bacteriophage families.
E) influenzavirus.
Answer: C
33) Which of the following statements about viruses is FALSE?
A) Viruses contain DNA or RNA but never both.
B) Viruses contain a protein coat.
C) Viruses use the anabolic machinery of the cell.
D) Viruses use their own catabolic enzymes.
E) Viruses have genes.
Answer: D
34) A lytic virus has infected a patient. Which of the following
would best describe what is happening inside the patient?
A) The virus is causing the death of the infected cells in the patient.
B) The virus is not killing any cells in the host.
C) The virus is incorporating its nucleic acid with that of the
patient's cells.
D) The virus is slowly killing the patient's cells.
E) The virus is infecting cells and then releasing only small
amounts of virus.
Answer: A
35) Some viruses, such as human herpesvirus 1, infect a cell without
causing symptoms. These are called
A) latent viruses.
B) lytic viruses.
C) phages.
D) slow viruses.
E) unconventional viruses.
Answer: A
36) Assume a patient had chickenpox (human herpesvirus 3) as a child.
Which line on the graph in Figure 13.2 would show the number of
viruses present in this person as a 60-year-old with shingles (human
herpesvirus 3)?
A) a
B) b
C) c
D) d
E) e
Answer: E
37) Assume a patient has influenza. During which time on the graph in
Figure 13.2 would the patient show the symptoms of the illness?
A) a
B) b
C) c
D) d
E) e
Answer: C
38) The following steps occur during multiplication of herpesviruses.
Which is the third step?
A) attachment
B) biosynthesis
C) penetration
D) release
E) uncoating
Answer: E
39) The following steps occur during multiplication of retroviruses.
Which is the fourth step?
A) synthesis of double-stranded DNA
B) synthesis of +RNA
C) attachment
D) penetration
E) uncoating
Answer: A
40) Oncogenic viruses
A) cause acute infections.
B) are genetically unstable.
C) cause tumors to develop.
D) are lytic viruses that kill the host cell.
E) have no effect on the host cell.
Answer: C
41) Which one of the following steps does NOT occur during
multiplication of a picornavirus?
A) synthesis of + strands of RNA
B) synthesis of - strands of RNA
C) synthesis of viral proteins
D) synthesis of DNA
E) None of the answers is correct.
Answer: D
42) Which of the following is most likely a product of an early gene?
A) capsid proteins
B) DNA polymerase
C) envelope proteins
D) spike proteins
E) lysozyme
Answer: B
43) Most RNA viruses carry which of the following enzymes?
A) DNA-dependent DNA polymerase
B) lysozyme
C) RNA-dependent RNA polymerase
D) reverse transcriptase
E) ATP synthase
Answer: C
44) The following steps occur during biosynthesis of a + strand RNA
virus. What is the third step?
A) attachment
B) penetration and uncoating
C) synthesis of - strand RNA
D) synthesis of + strand RNA
E) synthesis of viral proteins
Answer: C
45) What contributes to antigenic shift in influenza viruses?
A) worldwide distribution of the virus
B) a segmented genome
C) attachment spikes
D) ease of virus transmission
E) different virus subtypes
Answer: B
46) ________ were first identified in cancer-causing viruses and can
induce ________ in infected cells.
A) Herpes viruses; lesions
B) Oncogenes; transformation
C) T antigens; lysis
D) Glycoprotein spikes; syncytia formation
E) Segmented genomes; reassortment
Answer: B
1) The basic mechanism of viral multiplication is similar for all viruses.
Answer: TRUE
2) A viroid is a completely developed infectious agent composed of
nucleic acid and surrounded by a capsid.
Answer: FALSE
3) Binomial nomenclature is used to name viruses.
Answer: FALSE
4) Glycoprotein spikes are found on the capsids of all viruses.
Answer: FALSE
5) Positive sense RNA strands of viruses are treated like mRNA inside
the host cell.
Answer: TRUE
6) Dogs do not get measles because their cells lack the correct
receptor sites for that virus.
Answer: TRUE
7) Helical and icosahedral are terms used to describe the shapes of a
virus envelope.
Answer: FALSE
8) Viruses are the only known infectious agents that are obligatory
intracellular parasites.
Answer: FALSE
9) A segmented genome can result in antigenic shift.
Answer: TRUE
10) Most drugs that interfere with viral multiplication also
interfere with host cell function.
Answer: TRUE