MICROBIOLOGY A SYSTEMS APPROACH 7
2026 STUDY GUIDE REVISION SHEET CORE
CONCEPT BREAKDOWN
◉ Ivanovski and Beijernick.
Answer: discovered that tobacco disease caused by virus
◉ Loeffler and Frosch.
Answer: discovered foot-and-mouth disease caused by virus
◉ filterable virus.
Answer: infectious fluids were passed through filters designed to
trap bacteria.
the cell-free fluid remained infectious
= proved that an agent smaller than bacteria was the cause of
disease
◉ True/False: Viruses can be cultured using the same methods as
bacteria and fungi..
Answer: False; need living host such as chick embryo
◉ Pasteur developed a vaccine for the _______ virus.
,Answer: Rabies
◉ Viruses were discovered by filtering infectious fluid through a
filter designed to trap ________..
Answer: bacteria
◉ Unique properties of viruses.
Answer: Infectious particles; rather than organisms
Active or inactive; rather than alive or dead
Obligate intracellular parasites:
-cannot multiply unless they invade a specific host cell
-must instruct the genetic and metabolic machinery of the host cell
to make and release new viruses
◉ True/False: Viruses are alive..
Answer: False
◉ What percentage of the bacterial chromosome is composed of
viral genes?.
Answer: 10-20%
◉ Discuss the predominant view among scientists as to the nature of
viruses..
,Answer: infectious particle
◉ List and describe 5 unique properties of viruses..
Answer: not alive, do not reproduce on their own, very small, core
contains nucleic acids,
◉ virus size.
Answer: ultra microscopic size
electron microscope required to see them
parvoviruses: 20 nm in diameter
mimiviruses: 450 nm in length - larger than some small bacteria
cylindrical viruses: 800 nm long, but 15 nm in diameter
◉ capsid.
Answer: shell surrounds the nucleic acid
◉ nucleocapsid.
Answer: capsid and nucleic acid together
◉ envelope.
, Answer: usually a modified piece of the host cell membrane
◉ naked virus.
Answer: consists only of a nucleocapsid
◉ spikes.
Answer: found on both naked and enveloped viruses
project from either the nucleocapsid or envelope
allow viruses to dock with their host cells
spikes: protruding glycoproteins essential for attachment to the host
cell
◉ virion.
Answer: fully formed virus able to establish infection in a host
◉ capsomeres.
Answer: - identical protein subunits that spontaneously self
assemble to form the capsid
helical capsid- rod-shaped capsomeres that form a continuous helix
around the nucleic acid
2026 STUDY GUIDE REVISION SHEET CORE
CONCEPT BREAKDOWN
◉ Ivanovski and Beijernick.
Answer: discovered that tobacco disease caused by virus
◉ Loeffler and Frosch.
Answer: discovered foot-and-mouth disease caused by virus
◉ filterable virus.
Answer: infectious fluids were passed through filters designed to
trap bacteria.
the cell-free fluid remained infectious
= proved that an agent smaller than bacteria was the cause of
disease
◉ True/False: Viruses can be cultured using the same methods as
bacteria and fungi..
Answer: False; need living host such as chick embryo
◉ Pasteur developed a vaccine for the _______ virus.
,Answer: Rabies
◉ Viruses were discovered by filtering infectious fluid through a
filter designed to trap ________..
Answer: bacteria
◉ Unique properties of viruses.
Answer: Infectious particles; rather than organisms
Active or inactive; rather than alive or dead
Obligate intracellular parasites:
-cannot multiply unless they invade a specific host cell
-must instruct the genetic and metabolic machinery of the host cell
to make and release new viruses
◉ True/False: Viruses are alive..
Answer: False
◉ What percentage of the bacterial chromosome is composed of
viral genes?.
Answer: 10-20%
◉ Discuss the predominant view among scientists as to the nature of
viruses..
,Answer: infectious particle
◉ List and describe 5 unique properties of viruses..
Answer: not alive, do not reproduce on their own, very small, core
contains nucleic acids,
◉ virus size.
Answer: ultra microscopic size
electron microscope required to see them
parvoviruses: 20 nm in diameter
mimiviruses: 450 nm in length - larger than some small bacteria
cylindrical viruses: 800 nm long, but 15 nm in diameter
◉ capsid.
Answer: shell surrounds the nucleic acid
◉ nucleocapsid.
Answer: capsid and nucleic acid together
◉ envelope.
, Answer: usually a modified piece of the host cell membrane
◉ naked virus.
Answer: consists only of a nucleocapsid
◉ spikes.
Answer: found on both naked and enveloped viruses
project from either the nucleocapsid or envelope
allow viruses to dock with their host cells
spikes: protruding glycoproteins essential for attachment to the host
cell
◉ virion.
Answer: fully formed virus able to establish infection in a host
◉ capsomeres.
Answer: - identical protein subunits that spontaneously self
assemble to form the capsid
helical capsid- rod-shaped capsomeres that form a continuous helix
around the nucleic acid
