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Viruses (Viral Diseases (Emerging Diseases (Viruses that suddenly become…
Viruses
Viral Diseases
Animals
Vaccines
A harmless piece of pathogen that the immune system can kill so it knows how to defend itself
many diseases were eradicated or greatly reduced using vaccines
measles
polio
smallpox
Prions
Proteins that cause degenerative brain disease
scrapie
mad cow disease
prions act very slowly, ten years before symptoms
Prions are misfolded proteins in the brain
converts other healthy proteins and forms a chain
virtually indestructible
no known cure
Plants
most have RNA genome
Horizontal Transmission
external viral source
Vertical Transmission
inherits viral load from parent
Emerging Diseases
Viruses that suddenly become apparent are called emerging viruses
Pandemic
A worldwide outbreak
Epidemic
a widespread outbreak
Existing viruses mutate and immunity of the old disease is uesless
HIV/AIDS is an example of an emerging virus
west nile virus
ebola
Viral Struture
Capsid
The protein shell that enclosesa viral genome
polyhedral
adenoviriuses
Triangular facets
icosahedral viruses
complex shapes
rod shaped
called helical viruses
Built from protein subunits called Capsomeres
The different kinds of proteins is small
Bacteriophages
viruses that infect bacteria
T1-T8 phages
T2,4,6 are the T even phages
elongated icosahedral heads
protein tail piece with fibers
also called phages
Viral Envelope
Host cell phospholipids and membrane proteins
Proteins and Glycoproteins
Glyco proteins is a protein with a carbohydrate contently bonded
Derived from membrane of host cell
An accessory structure that helps virus infect the host
Viral enzyme molecules inside their capsids
Only 20nm
nucleic acid enclosed in a protein coat
can have a variety of different genetic material
RNA double strand
Dna single strand
DNA double strand
RNA single strand
Viral Genome
Provirus
integrated viral DNA in a host cell
never leaves
contrasts prophages that can leave the cell
Evolution
can infect any form of life
bacteria archaea fungi algae protists
Plasmids
small circular DNA molecules found in bacteria
Transposons
DNA segments that can move around in the cells genome
Plasmids Transposons and Viruses are all mobile genetic elements
Could have evolved and been the original source of viruses
believed to have evolved from bits of nucleear acids
Retrovirus
Animal viruses with the most complicated replicative cycles
Reverse Transcriptase
Transcribes RNA > DNA
this is backwards of normal DNA >RNA so its referred to as Retro or backwards
HIV (Human Immunodeficiency syndrome)
a retrovirus of medical importance
HIV turns into AIDS once the infection sets deep
HIV replicative cycle
reverse transcriptase molecules released
viral DNA is synthesized and enters the cells nucleus
Enters cell
integrates into DNA
permanent in the cell
reproduces and creates more
Enveoped viruses that have two molecules of single strand RNA and two molecules of reverse transcriptase
Viral Cycles
Lysogenic
Replication of phages without destroying host cell
The viral DNA integrated in the host DNA is known as a prophage
Lysoggenic means they are capable of activating the prophages and starting a lytic cycle
Phages that can do both lytic and lysogenic are called Temperate Phages
Phage attatches
Injects DNA
Dna is integrated into host DNA
Reproduces normally
Large pop of bacteria with prophages
Lytic
the host cell dies
at the end the bacteria cell lyses and releases the new phages
Virulent Phages only reproduce by the lytic phase
injects DNA and degrades host DNA
synthesis of viral genomes and proteins
assembly of phages
cell lysis and releases phages
attatches by binding to surface proteins
Restriction Enzymes
restrict phages ability to replicate within the bacteria
CRISPRS
DNA sequence that has phage DNA in the spacers
CAS are the nucleases proteins that identify and cut up phage proteins
bacteria have defense against phages so they dont go extinct