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