Chapter 5
Name this step: A virus can invade its host cell only through making an exact fit with a specific host molecule /Receptor sites/Specific surface structures on host to which viruses attach
Adsorption
Put the phases of the life cycle of animal viruses in the correct order: assembly penetration release adsorption synthesis uncoating
Adsorption,Penetration, Uncoating, Synthesis, Assembly, Release
Viruses contain either ____ or ____, NOT both
DNA or RNA
Prominent viral infections found in certain regions of the world:
Dengue fever, Rift Valley Fever, yellow fever
____ _____ of the viral envelope with the host cell membrane occurs with influenza and mumps virus -envelope merges directly with the cell membrane -nucleocapsid is released to the cells interior
Direct fusion
____________ Characteristics of Viruses -reproduce at fantastic rate -only in living cell -mutate
Living
___ ______ postulated that a living thing smaller than bacteria caused these disease.
Louis Pasteur
______ infection (aka latent infections) are when the viral genome becomes incorporated into the hosts cell DNA, can remain this way for long periods, host cell lives
Lysogenic Infection
_______ infection is when the host cell fills with virions and bursts that results in cell death
Lytic Infection
Tomatoes, potatoes, cucumbers, citrus trees, and chrysanthemums are often infected with _____. -____
Viroids
___ are noncellular or acellular infectious agents
Viruses
Viruses infections _____ types of cell.
every
Animla viral replication cell are ..... ( 6 Steps) -The length of replication cycle varies from __ hours in polioviruses to ___ hours in herpresviruses
-Absorption, penetration, uncoating, synthesis, assembly, release -8,36 hours
This step, ______, actually puts together the new viruses using the parts manufactured in the synthesis process: _____ capsids and _____ nucleic acids
-Assembly -new, new
Bovine Spongiform Encephalopathy (BSE) aka (___ _____ _____) --humans can contract disease consuming contaminated ___. -infected individual developed strain of Creutzfeldt-Jacob Disease -As of 2011, only ____ BSE-positive cows have been found to the 180k in UK
-Mad cow disease -beef -three
Structure of a Virus (3 parts)
-Nucleic Acid -Capsid -Envelop -Spikes?
____: Replication and Protein Production -______ viruses enter the hosts cell nucleus and are replicated and assembled there -____ viruses are replicated and assembled in the cytoplasm -_____ turn their RNA genomes into DNA
-Synthesis -DNA -RNA -Retrovirus
Bacteriophage was -discovered by _____ and d'Herel -from Greek phage meaning "_____" -most contain ____ stranded DNA, but some RNA exist as well -every bacterial species is _______
-Twort -eating -double -parasitized
Viruses can cause cancer in animals bc virus carries genes that ____ cause cancer & produce proteins that induce a ___ of growth regulation in the cell.
-directly -loss
external covering of nucleocapsid, usually modified piece of the host's cell membrane , -form when viral glycoproteins and oligosaccharides assosicate with the plasma membrane of the host cell -all envelopes have ____ bilayers
-envelope -phospholipid
Transformation: effect on the cell caused by oncongenic viruses -___ rate of growth -alterations in chromosomes -changes in he cell surface molecules -capacity to divide for an ____ period
-increased -indefinite
The ______ cycle was first worked out in bacteriophages (bacterial viruses). -Animal virus infections can be either ____ or ____.
-infection -lytic or lysogenic
Retrovirus is a single stranded RNA virus that stores its nucleic acid in the form of an _____ genome and target a host cell as an obligate parasite -Once inside host cell, cytoplasm uses its own _______ ______ enzyme to produce DNA from its RNA genome, the reverse of the usual pattern
-mRNA -reverse transcriptase
Creutzfeldt-Jacob Disease infects the human _____ system and causes gradual ______ and _____.
-nervous -degeneration -death
Viroids are virus looking agents that parasitize ____. -__ of avg size of virus -composed of _____ strands of RNA, lacking capsid or other type of coating
-plants -1/10 -naked
Sea water contains ___ ____ viruses per milliliter.
100 million
Icosahedral Viruses -their shape is derived from ___ triangular faces that make up the capsid -the capsid has ___ points of symmetry
20,12
Antibiotics are an effective method for treating viral infections. True False
False. Antibiotics are designed to target prokaryotes and have no effect on viruses.
Types of receptor binding: -_______ Virus: binding takes place b/w viral capsid and receptor -____ Virus: binding takes place between viral envelope proteins and receptor
Non-enveloped, enveloped
________ Characteristics of viruses -acellular (no cytoplasm or organelles) -carry out no metabolism on their own -must replicate using host cells metabolic machinery
Nonliving
Creutzfeldt-Jakob disease and Bovine spongiform encephalopathy are caused by prions. Which of the following best describes a prion? viral particle naked DNA infectious protein small bacterium naked RNA
Prions are infectious protein particles
Viruses and be ____ or ___.
RNA or DNA
Helical Capsids- ____ ______ _____ are shaped like hollow tubes with protein walls
Tobacco Mosaic Virus
colds, hepatitis, chickenpox, influenza, herpes, warts are?
acute infections
____ ____ that block viral replication by targeting the function of host cells can have severe side effects
antiviral drugs
Papillomaviruses and Epstein-Barr Virus are _____-causing viruses
cancer
Protein shell that surrounds the nucleic acid, protect viral genetic material and aid in its transfer between host cells
capsid
Viruses consists of more than 1 molecule of DNA or RNA Nucleic Acid is surrounded or coated by a protein shell/coat of protein called _______
capsid
Capsid is composed of identical protein subunits called _____ or ______.
capsomeres or protomers
Polio and neonatal rubella viruses that cause long term ____.
disability
Some cylindrical viruses can be relatively long (800 nm) but are so narrow in diameter (15 nm) that their visibility is limited without an _____ microscope
electron
Penetration through ________ where entire virus is engulfed by cell and enclosed in _____ or vesicle.
endocytosis, vacuole
Virions having envelopes -enveloped viruses infect humans and other animals
enveloped viruses
Influenza virus has an ______ virus with a ____ nucleocapsid
enveloped, helical
Rabies, AIDS, and Ebola are viruses with ____ mortality rates.
high
____ naturally occur in human cells and is used with some success intreating and preventing viral infection
interferons
Viruses are infectious agents with both ____ and _____ characteristics.
living, nonliving
Virions lacking envelopes
naked infections
Antibiotics designed to disrupt prokaryotic cells have ___ ______ on viruses.
no effect
the capsid together with the nucleic acid
nucleocapsid
_____ viruses: viruses capable of initiating tumors, experts estimate that up to 20% of human cancers are caused by viruses
oncogenic
Pasteur proposed the term virus, which is latin for _____.
poison
_____ infected cell - 100,000 virions (polio) is a contagious disease that was eliminated from western hemisphere
poliovirus
______ synthesize DNA and RNA
polymerases
_____ infected cell: 3000-4000 virions (smallpox)
poxvirus
A common feature of spongiform encephalopathies is distinct protein fibrils in brain tissue called ___.
prions
_______ copies RNA
replicases
____ synthesizes DNA from RNA
reverse transcriptase
Release: The # of viruses released by infected cells in variable, controlled by ___ of the virus or ___ of the host cell.
size, health
Viruses are the ____ infectious agent, the smallest being ______ around 20 nm in diameter and the largest being ________ around 450 nm in length.
smallest, parvoviruses -mimiviruses
can be found on naked or enveloped viruses, project from the nucleocapsid or the envelop, allow viruses to dock with host cells
spikes
______ occurs when enzymes in the vacuole dissolve the envelope and capsid, virus fuses with the wall of the vesicle, viral nucleic acid is released into the cytoplasm
uncoating
type 1 diabetes, multiple sclerosis, various cancers, Alzheimer's disease, obesity are examples of viruses with possible connection to chronic affiliations with an ______ cause.
unknown
_____ stimulate immunity and are extremely valuable, but are only available for a limited number of viral diseases.
vaccines
a fully formed virus that is able to establish an infection in a host cell/an intact viral particle
virion
scientists who study viruses
virologists
Study of virsuses
virology
The flexible cell membrane of host of penetrated by ____ virus or its ___ ____.
whole, nucleic acid