Viruses
True or False: Viruses have a nucleus and organelles.
False; they have neither nucleus nor organelles
Nonenveloped virus
Nonenveloped viruses cause the host to burst to release viral particles. -lack an envelope derived from the host's cell membrane
retrovirus
RNA virus that contains reverse transcriptase
Basic roles of Head, Sheath, and Tail
-Head stores genetic material. -Sheath provides a passage way for genetic material to be injected into the host bacteria. -Tail fibers attach to the host bacteria.
Describe information about the "capsid"
A capsid is the protein shell enclosing the viral genome.
Enveloped virus
Enveloped viruses bud off the host's membrane. -have an envelope derived from the host's cell membrane
Life Cycle: Lysogenic Stage
In the lysogenic phase there are generally no symptons. Under certain conditions the lysogenic lifestyle can switch to a lytic lifestyle. Often, a virus is found at this stage under harsh conditions. The virus is a prophage at this stage. 1) The virus binds to bacteria (host) 2) The virus inserts its DNA into the bacteria 3) The viral DNA gets incorporated into the cell's chromosome 4) Viral DNA is replicated along with chromosomal material
Life Cycle: Lytic Stage
In the lytic stage, many viral particles are made and copies are sent back into the environment. 1) The virus attaches to bacteria (host) 2) The virus inserts its DNA into the bacteria 3) The virus takes over the cell's machinery 4) The virus reproduces itself and self-assembles. 5) The host cell is destroyed
Describe what viral genomes are like.
The genome is usually organized as a single linear or circular molecule of nucleic acid. It can be DNA or RNA, and it can be single or double stranded, depending on the virus.
True or False: A protein coat covers the nucleic acid.
True
True or False: Viruses are generally smaller than bacteria
True
Genomic content RNA or DNA
Viruses can contain either RNA or DNA as their genomic content. Out of the RNA viruses, those that convert their genome into DNA inside their host are called retroviruses.
Is HIV a retrovirus?
Yes
protease inhibitor
blocks capsid synthesis
inactivated virus
cannot replicate in a host cell
Prions
composed of protein with no nucleic acid
Emerging diseases
diseases that evolve in a geographically isolated area and are caused by pathogenic viruses
proto-oncogene
gene that can be converted into a cancer-forming gene
oncogene
gene that causes cancer
Look at this link to understand better lytic versus lysogenic...
http://lh6.ggpht.com/-ezqWWBNtWQc/UThK7PGNYQI/AAAAAAAAE3Y/RZNa1X7x26w/lytic%252520and%252520lysogenic%252520cycle_thumb%25255B5%25255D.jpg?imgmax=800
Viroids
infectious disease agents that have a single stand of RNA and have no capsid
vector
intermediate host that transfers a pathogen
lysis
the bursting of a cell, releasing viruses
reverse transcriptase
uses RNA as a template to make DNA (hence, "reverse transcription". It's RNA to DNA instead of DNA to RNA)
Bacteriophages
viruses that infect bacteria
virulent
viruses that reproduce by the lytic cycle
temperate viruses
viruses whose replication includes the lysogenic cycle
attenuated virus
weakened form of a virus
Prophage
when the DNA temperate phage is integrated into the host's chromosome. A prophage is a bacteriophage genome inserted and integrated into the circular bacterial DNA chromosome or existing as an extrachromosomal plasmid. This is a LATENT form of a phage, in which the viral genes are present in the bacterium without causing disruption of the bacterial cell.