virology - study of viruses
DESCRIPTION
Discovery of Viruses Edward Jenner (1796) developed smallpox vaccine using milder cowpox viruses Beijerinck (1897) coined the Latin name "virus" meaning poison Wendell Stanley (1935) crystallized sap from tobacco leaves infected with a virus & found virus was made of nucleic acid & protein Viruses couldn't be seen until the electron microscope was invented in the 1930s tiny, much smaller than a cell and only visible with advanced electron microscopes;TRANSCRIPT
Virology - study of viruses
Objective: G2 - Describe viral structure, reproduction, & the
role of viruses in causing diseases, and compare the structure of
viruses to cells Virology - study of viruses tiny, much smaller
than a cell and only visible with advanced electron microscopes;
Discovery of Viruses Edward Jenner (1796) developed smallpox
vaccine using milder cowpox viruses Beijerinck (1897) coined the
Latin name "virus" meaning poison Wendell Stanley (1935)
crystallized sap from tobacco leaves infected with a virus &
found virus was made of nucleic acid & protein Viruses couldn't
be seen until the electron microscope was invented in the 1930s
tiny, much smaller than a cell and only visible with advanced
electron microscopes; Viral Characteristics
Non living Not made up of cells Cannot grow or replicate on their
own Must be reproduced in living cells Can ONLY reproduce inside of
a living host cell
Some can cause disease (smallpox, measles, mononucleosis,
influenza, colds, AIDS, Ebola) Highly host specific (only infect
certain cells)
Viruses are classified into 2 main groups by their nucleic acid ---
DNA or RNA Viruses Viral Structure Consist of a nucleic acid core
(DNA or RNA) and a protein coat called the capsid that allow them
to identify a specific type of cell and attach to it Lack ribosomes
& enzymes needed for protein synthesis or metabolism
Bacteriophage---- viruses that infect bacteria HIV - attacks
T-cells of the human immune system Virus Replication Viruses cannot
reproduce on their own, and must infect a host cell in order to
create more viruses. Viruses use their own genetic material and the
host cell's machinery
1. Penetration - surface proteins bind to host, and release genetic
material (DNA or RNA) into the cytoplasm 2. Replication - the viral
genetic material is copied 3. Transcription - the genetic material
is used as a blueprint, for the cell to make messenger RNA which is
used to make viral proteins 4. Protein synthesis - occurs in the
cytoplasm (ribosomes), viral proteins are made 5. Viral Assembly -
the viral genetic material (from replication) is surrounded by the
newly made viral proteins 6. Release - viruses emerge from the cell
by "budding" from the cell membrane or bursting out of the cell
(this causes the cell's death) Viruses are about a thousand times
smaller than bacteria Lysogenic Cycle Lysogenic Pathway - the virus
stays within the cell until certain environmental triggers cause it
to enter the lytic cycle the virus stays within the cell until
certain environmental triggers cause it to enter the lytic cycle
Lytic cycle Lytic Pathway - rapid replication of the virus, ending
in cell lysis (or death). More viruses are released to infect other
cells lytic cycle (see figure above): A virus particle attaches to
a host cell. The particle releases its genetic instructions into
the host cell. The injected genetic material recruits the host
cell's enzymes. The enzymes make parts for more new virus
particles. The new particles assemble the parts into new viruses.
The new particles break free from the host cell. Human
Immunodefiency Virus (HIV) - causes AIDS
Retrovirus - RNA inside a protein coat HIV infects one particular
type of immune system cell, called a T-helper cell that functions
in the bodys immune response. Once infected, the T-helper cell
turns into a HIV-replicating cell. There are typically 1 million
T-cells per one milliliter of blood. HIV will slowly reduce the
number of T-cells until the person develops AIDS. Check for
Understanding
NO !!! 1. Are viruses alive? _________ 2. Why or why not?
________________________ 3. Can viruses reproduce on their own?
_______ 4. What do viruses need in order to reproduce?
_________________________ Not made up of cells No A host cell 5.
Structurally, what do viruses have in common with living
things
6. What type of cell do bacteriophages attack?________________ 7.
Which body system do T-cells belong to?________________ Genetic
information bacteria Immune