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Non-viral Infectious Agents Viroids- The smallest known particle that can replicate. Single Strand of RNA Disrupt plant cell metabolism Can destroy entire crops Prions – Abnormal forms of proteins that clump together inside cells. Clumping eventually kills the cell Example Mad Cow Disease
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Non-Living Infectious Agents Viruses
What are they? How do they work? Where do they come from? And What
good are they? Non-viral Infectious Agents
Viroids- The smallest known particle that can replicate. Single
Strand of RNA Disrupt plant cell metabolism Can destroy entire
crops Prions Abnormal forms of proteins that clumptogether inside
cells. Clumping eventually kills the cell Example Mad Cow Disease
Overview of Viruses Nonliving Composed of Nucleic acid and
protein
Cause many diseases Virology Study of Viruses Comparison of Viruses
and Cells below Char. Of Life Virus Cell Growth No Yes Homeostasis
Metabolism Mutation Nucleic acid DNA or RNA DNA Reproduction Only
within host cell Independently by cell division Structure Nucleic
acid core, protein covering, some have envelope Cytoplasm, cell
membrane, etc.. Characteristics of Viruses
2 essential features 1. Nucleic Acid May be DNA or RNA Helical,
closed loop, or long strand 2. Protein Coat called CAPSID Some have
ENVELOPE Ex.Influenza, chickenpox, herpes simplex, HIV VIRAL SHAPE
Icosahedron 20 triangular faces Ex.) herpes, chickenpox, polio
Helix Coiled spring EX.) Rabies, measles, tobacco mosaic
Bacteriophages: like tiny little syringes that injectDNA from the
virus into the cell Lytic Cycle 1. Attachment- Virus finds host
cell Host cell DNA
Bacteriophage Host cell DNA 1. Attachment- Virus findshost cell 2.
Entry- Viral DNAinjected into host 3. Replication- Host makesviral
DNA & parts 4. Assembly- New viruses made 5. Lysis &
Release-viruses burst out of host(dies); Find new host Here is a
non-enveloped bacteria virusinserting its DNA into a bacterial
cell. Some virus are pushed out by the cell,taking some of the cell
membrane with them. Lysogenic Cycle After Step #2 of the Lytic
Cycle, the Virusmay become Dormant and enter into theLysogenic
cycle Dormant- non-active time of virus Host is infected, but
doesnt know it Ex: Herpes (cold sores) Person doesnt havethem all
the time, but has outbreaksthroughout year Ex: HIV Mono Lysogenic
Cycle From Step #2 Lytic cycle, enters Lysogenic cycle here
2. Entry- Viral DNAinjected into host 3. Integration - Viral
DNAbecomes part of host DNA 4. Cell Multiplication Hostreplicates
with viral DNA Many celldivisions 5. Cell enters back into Lytic
Cycle-Assemble, Lysis & Release Provirus Classification of
Viruses
1. By Shape Host type function Retroviruses attacka certain way.
DNA viruses attackanother way. Animal viruses Plant viruses
Bacteria viruses Viruses and Human Disease
Control and Prevention of spread. Vaccination & Antiviral drugs
Ex.) chickenpox vaccine, AZT, Acyclovir, proteaseinhibitors.
Emerging Viruses exist in isolated habitats Do not usually infect
humans unlessenvironmental conditions favor contact. Several
viruses are now linked to cancerssuch as leukemia, liver cancer,
Burkittslymphoma, cervical cancer. English physician and scientist
from Berkeley, Gloucestershire, who was the pioneer of smallpox
vaccine Cowpox and smallpox are closely related, but cowpox is a
much less serious disease than smallpox.
Jenner noticed milkmaids were immune to smallpox. He used puss from
a cowpox blister to inocculate an 8 year old boy He called his
method vaccination, from the Latin word vacca, or cow, and today we
use vaccination to refer to immunization against any disease. A
vaccine contains a killed/weakened part of a germ.
When a person receives a vaccine, the body reacts by making
protective antibodies. Wendell M. Stanley Wendell M. Stanley
crystallized and described the molecular structure of the tobacco
mosaic virus. PAPOVAVIRUSES:Tumor causing viruses Most common:Human
papillomavirus (HPV) (warts) ADENOVIRUSES: causes respiratory
issues and pink eye HERPESVIRUSES: easily transmitted by direct
contact with a lesion or the body fluid of an infected individual
POXVIRUSES PICORNAVIRUSES The name is derived from pico, meaning
small, and RNA, referring to the ribonucleic acid genome, so
"pico-rna-virus" literally means small RNA virus. Ranges from the
common cold to polio! MYXOVIRUSES RHABDOVIRUSES RETROVIRUSES: genes
are encoded in RNA instead of DNA Here is a classic picture of HIV
viralprogeny being released from thesurface of a T- cell.Notice
themembrane coating they receive. Ebola Virus Some therapies that
have worked havebeen when patients receive blood fromconvalescent
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