Bacteriophages' contact and attachment to host cells are mediated by ___-_____ _____.
cell-surface receptors
Cell-surface receptors are proteins that are _____ to the host species and which bind to a specific ____ component.
specific, viral
Bactieral cell receptors are normall used for important functions for the ____ cell, such as sugar uptake.
host
Most bacteriophages (phages) inject only their ____ into a cell through the cell envelope, while the phage ____ remains outside, attached to the cell surface and it termed a _____.
genome, capsid, ghost
Name the bacteriophage life cycle:
- bacteriophage quickly replicates, killing the host cell
Lytic cycle
Name the bacteriophage life cycle
- Bacteriophage is quiescent
- Integrates into cell chromosome, as a prophage
- Can reactivate to the other life cycle
Lysogenic, it can reactivate to become lytic, based on environmental cues. Generally, events that threaten host cell survival trigger lytic burst
Name the type of exit of a phage from the host cell:
- make enzyme that breaks down cell wall
- host cell bursts to release progeny phage
Lysis
Name the type of exit of a phage from the host cell:
- Filamentous phages can extrude individual progeny through cell envelope
- Host cell grow slowly but do not die
Slow release
Name the type of bacteria host defense against phage infection:
- altered receptor proteins
genetic resistance
Name the type of bacteria host defense against phage infection:
- cleave viral DNA lacking methylation
restriction endonucleases
Name the type of bacteria host defense against phage infection:
- Clustered regularly interspaced short plaindromic repeats
- a bacterial immune system
CRISPR integration of phage DNA sequences
True/False: bacteriophages have greater complexity and diversity of viral replication cycles than we see in animal and plant viruses.
False, it's the opposite way around
Animal viruses bind specific receptor proteins on their host cells, and the receptors determine viral _____.
tropism
Most animal viruses enter host as _____. Upon entering, they undergo ____, where the genome is released from its capsid.
virions, uncoating
What type of animal virus is this:
- can utilize the host replication machinery
DNA virus
What type of animal virus is this:
- use an RNA-dependent RNA-polymerase to transcribe their mRNA
RNA viruses
What type of animal virus is this:
- Use a reverse transcriptase to copy their genomic sequence into DNA for insertion in the host chromosome
Retroviruses
All animal viruses make proteins with ____ ribosomes.
- Translation occurs in the ______.
host, cytoplasm
Animal virus assembly of new virions:
- may occur in the ____ or _____
cytoplasm, nucleus
Name two ways that animal viruses are released from the host cell:
- lysis of cell
- budding
In the budding release of an animal virus from host cell:
- virus passes through _____
- _____ surround capsid to form envelope
- all ______ viruses bud from a membrane (either plasma or organelle)
- membrane
- membrane lipids
- enveloped
Many human cancers are caused by _____ viruses, such as epstein-Barr virus (lymphomas) and hepatitis C virus (liver cancer)
oncogenic
Oncogenic viruses _____ the host cell to become cancerous.
transform
Mechanisms of oncogenesis include:
- insertion of an _____ into the host genome
- integration of the _____ viral genome
- expression of viral ______ that interfere with host cell cycle regulation
- oncogene
- entire
- proteins
In contrast to animal viruses and bacteriophages, plant viruses infect cells by mechanisms that do not involve:
specific membrane receptors
Entry of plant viruses into host cells usually requires:
mechanical transmission
What three routes do most plant viruses enter by?
- contact with damaged tissues
- transmission by animal vector
- transmission through seed
Within a plant, the thick ___ ___ prevent a lytic burst or budding out of virions.
cell wall
Plant viruses are transmitted to uninfected cell by:
plasmodesmata
Definition:
- membrane channel that connect adjacent plant cells
- inner channel connects the ER
plasmodesmata
How do plant and animals show genetic resistance to viruses?
hosts continually experience mutations
Bacteriphages may be cultured either in ____ ____ (in liquid) or as isolated plaques on a ____ ____ (on a plate).
batch culture, bacterial lawn
Batch cultures of viruses generates a ____ curve.
step
Animal viruses can be cultures within whole animals by serial inoculation, which ensures that the virus strain maintains its original ______.
virulence
_____ viruses, which kill their hosts, are outnumbered by _____ viruses, which are "along for the ride"
acute, persistent
Virus to bacteria ratios range from ______ in marine and aquatic environments to _______ in soils.
1:100, 1:1,000
On a global scale, viruses play a significant role in the _____ balance
carbon
When a bacterial cell is infected by a bacteriophage, what happens to the viral capsid?
D) it remains on the outside of the host cell
The primary factor determining the life cycle of an animal virus is the form of its
B) genome
Marine viruses play a significant role in which of the following cycles?
A) the carbon cycle
When a bacterial cell is infected by a bacteriophage, what happens to
