Tortora Micro Chapter 13 Study

Science Biology Virology

Tortora Micro Chapter 13

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Brock Biology of Microorganisms

14th Edition
David A. Stahl, John M Martinko, Michael T. Madigan

1,704 solutions

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Terms in this set (89)

Nucleic acid (DNA or RNA), Protein coat (capsid),

What are viruses composed of?
sometimes a Lipid envelope

Are viruses unicellular, Acellular; No ribosomes, no cell membrane, no

multicellular, both or acellular? cytoplasm
Why?

How would you describe a Obligate intracellular parasite

virus?

Are viruses classified into one No; viruses cannot be classified in a Domain; they
of the 3 Domains? If no, why have no ribosomes
not?
Tortora
Can viruses Micro
be grownChapter
in a lab? 13 Yes, they can be grown in a lab; through a living,
If yes, how? reproducing cell (Host cell)

1-One type of Nucleic acid 2-Made up of a

Nucleocapsid 3-Specific only for certain Host cells
List 5 Universal characteristics
4-Uses Host cell's reproductive machinery to make
of Viruses
little viruses 5-Can produce structures that can
transfer Nucleic acid to cell

What happens 1 minute after Normal Host cell reproduction stops

virus infects a cell?

What happens 10 minutes after Host cell becomes a Viral Reproducing Machine
virus infects a cell?

What microscope do you need An Electron microscope

to see viruses?

Give an example of a small virus Polio-20 nm

Give an examples of a large Pox-400 nm, and Ebola-950 nm

virus

What is the smallest Bacteria? Chlamydia-1000 nm

Give an example of a Normal- E. coli-3000 x 1000 nm

sized Bacteria

Define Virion A fully-developed virus

What is a Virion composed of? A Virion is composed of a Nucleocapsid

What does Nucleo refer to? Nucleic acid

Tortora Micro
What does Chapter
Capsid refer to? 13 Protein coat

Define capsomeres Protein subunits

Presence or absence of a Lipid envelope can help ID

If a Virion has a Lipid envelope?
the virus

Describe a Virion's DNA Double-stranded or single-stranded Helix

Describe a Virion's RNA Double-stranded or single-stranded Linear

For both DNA and RNA, the Helical, Linear, Circular or Segmented
shapes of the Virion's
chromosomes can be:

A cylindrical Helical array of capsid proteins

Describe a Helical virus. Give an
wrapped around a Helical filament of Nucleic acid.
example.
Ex. Rabies

Describe a Polyhedral virus. A many-sided virus; most commom is Icosahedral. Ex.

Give an example. Polio

Some viruses have a Lipid Enveloped helical: Influenza - Enveloped polyhedral:

envelope. Give an example of Herpes
enveloped helical and
enveloped polyhedral.

Some viruses have more than Complex viruses - have more than one shape. Ex. Pox
one shape. They are called? viruses
Give an example.

1-Type of Nucleic acid 2-Morphology 3-Envelope or

List the 4 things the Taxonomy
No Envelope 4-Method of Reproduction in Host cell
of Viruses is based upon.
(Lytic or Lysogenic)
Tortora Micro Chapter 13 1-Virus attaches to Host cell 2-Nucleic acid is
transferred to Host cell 3-Virus & Host cell's Nucleic
List the steps of Lysogenic Viral
acids combine 4-Replication of combined Nucleic
Multiplication
acid by Host cell 5-Host cell divides into 2 daughter
cells (Temperate phages)

List the Positive results of 1-Immune to infestation from same viruses 2-Gain
Lysogeny for the Host cell. new properties 3-Gain new genes

Under normal conditions, a Repressor proteins, Lytic

Host cell has ________ ________ that
prevent it from going into the
________ cycle.

Under negative conditions, a Repressor proteins, Lytic

Host cell's ________ ________are
inhibited, & it goes into the
_________ cycle.

In the Lytic cycle, define the Virus attach to a specific Host cell receptor site that
Attachment/Absorption step. allows only certain viruses to attach

Virus produces Lysozyme that breaks down cell wall,

In the Lytic cycle, define the
or membrane of Host cell, to allow the injection of
Penetration step.
the Virus's Nucleic acid into the Host cell

Host's Nucleic acid is destroyed, and Viral DNA is

In the Lytic cycle, define Gene
replicated using the Host cell's reproductive
Expression
machinery

In the Lytic cycle, define Virus makes Host cell produce more viruses, also
Assembly/Maturation placing capsids around the new little viruses
Tortora Micro Chapter 13
Lysis of Host cell
Bacterial cell bursts, and Virulent Virions are released
to infect other Host cells

Refers to the time between when the Host cell is first

Burst time?
attached to the virus, until the cell Lyses

Refers to the Number of Virulent Virions that are

Burst size?
released from each Host cell; between 50-200

In order the cultivate a virus Reproducing Host cells, Tissue

successfully, it must be done in
_________ __________ __________ in __________
culture.

Viruses are hard to grow in Labs Reproducing Host cell

because they require a _________
_________ _________

Viruses are easiest to grow in Bacterial cells

________ ________

More viruses are being grown in Mammalian; closest to Human cells

what type of cells? And why?

Define Plaque Assay Test for how Virulent a virus is

PFUs are __________ __________ __________ Plaque forming units

Bacteria is placed on a Media plate, a virus is

An example of how PFUs are dropped into the plate, incubated; you're looking for
counted is: clear area where Bacteria went through the Lytic
phase
Tortora Micro
When counting PFUs, Chapter
each 13 One Plaque
clear area represents __________
__________.

When counting PFUs, each One Virion

Plaque represents __________
__________.

Define Pathogenicity Ability to cause disease

Define Virulency Degree of Pathogenicity

(Infectious Dose) The dose necessary to INFECT 50%

What does ID50 stand for?
of the test organisms

(Lethal Dose) The dose necessary to KILL 50% of the

What does LD50 stand for?
test organisms

Some viruses can only be Chicken embyros

grown in a living organism. What
organism is used most?

List the 3 types of Tissue Primary cell lines, Diploid cell lines,
cultures Continuous/Immortal cell lines

Derived from tissue slices; these tend to die out after

Define Primary cell lines
only a few generations

Developed from Human embryos; maintains for

Define Diploid cell lines approx 100 generations; widely used for viruses that
require a Human host
Tortora Micro Chapter 13
Define Continuous/Immortal
Routinely grown in a Lab; utilizing cancerous cells or
transformed cells; maintains for an indefinite number
cell lines
of generations

Most studied Phages? T Evens; T2, T4, T6

T evens are usually combined E. coli

with _________________

Normally, E. coli produces 3000

___________ genes in 40 minutes

E. coli + T4 produce 600,000

________________genes in 40 minutes

1-Attachment 2-Penetration (BUT entire Virion enters

Host cell) 3-UN-coating; host cell separates capsid
List of steps for Replication of from Nucleic acid 4-Biosynthesis; Nucleic acid is
Animal Viruses replicated 5-Coating; making capsids and putting
them ON the replicated Nucleic acid 6-Release of
Virulent Virions 7-Host cell is Lysed

Difference between Viral In Proks, only the Nucleic acid enters the Host cell. In
replication in Proks Host cells Euks: 1- the entire Virus enters the Host cell; 2- Un-
vs. Euks Host cells coating occurs

List 3 types of infections in Lytic, Persistent, Latent

Eukaryotic Viruses

Define Lytic infection in Most severe; Virus destroys Host cell Ex: common
Eukaryotic viruses cold, Polio

Define Persistent Infection in Virus is replicated w/in Host cell, but Host cell
Eukaryotic viruses remains Ex: Hepatitis B
Tortora Micro Chapter 13
Define Latent Infection in
Virus is in Host cell, but remains dormant; can
"trigger" Persistent as well as Lytic Ex: HIV, Herpes,
Eukaryotic viruses
Shingles

Cancers are associated with An uncontrolled division of abnormal cells

viral origins. What is cancer?

Cells that do not metastasize, nor do they invade or

Define Benign
injure surrounding tissues

Cells that do metastasize (spread), and are not self-

Define malignant
limiting; invade and injure surrounding tissues

Animal viruses (Eukaryotic) are DNA, RNA

divided into __________ or __________
viruses

Animal virus DNA replicates Nucleus, DO Ex: Herpes

w/in the Host cell's __________, and
_________interact with the Host
cell's Nucleic acid

Animal virus RNA replicates Cytoplasm, DON'T Ex: Polio

w/in the Host cell's __________, and
__________interact with the Host
cell's Nucleic acid

1-Intestinal form 2-Paralytic Polio (Poliomyelitis:

Give 2 forms of Polio
attacks neurons in the CNS)

HIV is known as a _____________virus Retro

Tortora Microproduce
When Retroviruses Chapter 13 reverse transcriptase, DNA
__________ ____________ , they can use
RNA as the template to make
__________

What makes it hard to prevent Genetic Material

or treat these Retroviruses is,
their __________ __________ is
constantly changing

Insects are used a lot as __________ Carriers

for viruses in Genetic
Engineering

Plant viruses are carried Wind, insects

by__________, __________ etc.

Viruses that infect plants can Less and less cropland; Decrease in crop yields won't
have what type of impact provide enough food to feed us all; this would cause
world-wise? chaos

Small, infectious entity consisting only of Ribonucleic

What is a Viroid?
acid (RNA) without a Protein coat

Where are Viroids found? And Plants only, so far; Citrus, cucumbers, potatoes
what do they ruin?

A small proteinaceous infectious disease-causing

What are Prions? agent that is believed to be the smallest infectious
particle

Neurological diseases; i.e., Mad Cow disease,

What do Prions cause?
Spongiform Encephalopathies
Tortora Micro Chapter 13 Degenerative diseases of the brain characterized by
Define Spongiform the development of porous sponge-like lesions in
Encephalopathy brain tissue, and by deterioration in neurological
functioning; specifically, prion disease.

1-Co-Evolution with more complex life forms

List 3 Theories of How Viruses
2-Escaped Gene Theory
Developed
3-Retrograde Evolution

Some forms replicated from RNA to DNA; others

Define Co-evolution of a Virus
retained simple levels

Cells lost control of their genetic material, genes

Define Escaped Gene Theory
escaped, and became their own separate units

Possibly Atypical Prokaryotes who lost their

Define Retrograde Evolution biochemical capabilities, kept only their genetic info,
and regressed back to viral stage

Name 2 Atypical Obligate Rickettsia, Chlamydia

Intracellular Prokaryotes that
are also Obligate Intracellular
Parasites--like viruses?