Part 2 Flashcards
- nucleic acid
- Single-stranded genomes may be of
positive (i.e. mRNA) or negative (i.e. antimRNA) polarity.
Genome
- nucleic acid
- Single-stranded genomes may be of
positive (i.e. mRNA) or negative (i.e. antimRNA) polarity.
- a coat of protein arranged in one of several
possible morphologies - encloses the genome.
Capsid
- a coat of protein arranged in one of several
possible morphologies - encloses the genome.
- cubical with 20 flat sides
Icosahedral capsid
- cubical with 20 flat sides
- spiral
Helical capsid
- spiral
- sub-unit of capsid
Capsomere
- sub-unit of capsid
- Certain viruses also contain an additional
phospholipid bilayer derived from the host
cell and surrounding the protein capsid.
Envelope
- Certain viruses also contain an additional
phospholipid bilayer derived from the host
cell and surrounding the protein capsid.
- glycoprotein that functions as attachment or
as an enzyme
Spikes
- glycoprotein that functions as attachment or
as an enzyme
- a complete viral particle
Virion
- a complete viral particle
- with circular RNA molecules
- without capsid and envelope
Viroid
- with circular RNA molecules
- without capsid and envelope
- viroid-like particles
- passengers in virus capsids
Virusoids
- viroid-like particles
- passengers in virus capsids
- believed to consist of a single type of
protein molecule without Nucleic Acid
content
Prions
- believed to consist of a single type of
protein molecule without Nucleic Acid
content
Virus Classifications
Virus Classifications
1. According to Type of Genetic Material
a. DNA
b. RNA
2. According to Shape of Capsid
a. Helical
b. Polyhedral
o example: Icosahedral (20 sides)
3. Number of Capsomeres
4. Size of Capsomeres
5. Presence or Absence of Envelope
Recognition and attachment to its host cell’s
carbohydrate receptors
- viruses are ________ as to the type of host cell
in which they can multiply and so
recognition is often very specific.
(___________) - Viruses adsorb to their host cell surface via
specific ______________ molecules, often
glycoproteins. - Adsorption is generally _________________ and
_________ independent.
Recognition and attachment to its host cell’s
carbohydrate receptors
- viruses are limited as to the type of host cell
in which they can multiply and so
recognition is often very specific.
(TROPISM) - Viruses adsorb to their host cell surface via
specific antireceptor molecules, often
glycoproteins. - Adsorption is generally temperature and
energy independent.
Penetration into the host cell
- often energy dependent and may occur by
three different mechanisms;
a.
b.
c.
Penetration into the host cell
- often energy dependent and may occur by
three different mechanisms;
a. translocation of the plasma membrane
b. pinocytosis into cytoplasmic vacuoles, or
c. fusion of the plasma membrane with the viral envelope forming a SYNCYTIA
Penetration into the host cell
- Non-enveloped viruses may enter via
________________ or _______________; enveloped
viruses typical enter via fusion. Once inside
the host cell
Penetration into the host cell
- Non-enveloped viruses may enter via
translocation or pinocytosis; enveloped
viruses typical enter via fusion. Once inside
the host cell
- releases the viral genome to be replicated.
Uncoating
- releases the viral genome to be replicated.
- production of _______________ and __________________
- Viral transcription leads to the synthesis of _______ (encodes early(structural) and late viral proteins)
Macromolecular synthesis
- production of nucleic acid and protein polymers
- Viral transcription leads to the synthesis of mRNA (encodes early(structural) and late viral proteins)
- structural proteins, genomes and enzymes are assembled
Viral assembly
- structural proteins, genomes and enzymes are assembled
Release
______
- causes rapid host cell death
Release
Lysis
- causes rapid host cell death
_________
- viral envelopes are acquired from
host’s cell membrane
- may not result to rapid cell death
Release
Budding
- viral envelopes are acquired from host’s cell membrane
- may not result to rapid cell death
Nonspecific defenses
__________________
anatomical barriers,
viral inhibitors in _______ and _________.
Phagocytosis is somewhat ________.
Nonspecific defenses
Prior to infection
anatomical barriers,
viral inhibitors in fluids and tissues.
Phagocytosis is somewhat variable.
Nonspecific defenses
________________
_____ (viral replication is strongly influenced by temperature) and
inflammatory processes including edema, leucocyte accumulation, local hyperthermia, reduced oxygen tension and altered cell metabolism can all act to reduce _______________.
Nonspecific defenses
After infection
fever (viral replication is strongly influenced by temperature) and
inflammatory processes including edema, leucocyte accumulation, local hyperthermia, reduced oxygen tension and altered cell metabolism can all act to reduce viral replication.
___________________
- prevent adsorption to target cells and cytotoxic T-lymphocytes, which recognize virally-infected cells and
destroy them, reducing viral production.
Specific host defenses
antiviral antibody
- prevent adsorption to target cells and cytotoxic T-lymphocytes, which recognize virally-infected cells and
destroy them, reducing viral production.
