Transcript No Slide Title

VIRUS
MEANS
“POISON”!
MADE OF
PROTEIN AND
NUCLEIC ACID
(EITHER DNA or
RNA)
Protein part is
the CAPSID
NA is
inside
capsid
Living or Not?
They have
genetic material
& structural
proteins
BUT:
No Ribosomes
No Organelles
No Nucleus
Can’t Use Energy
AND:
They Cannot
Reproduce
on their own
SO:
They are
NON-LIVING!
They are
referred to as
Obligate
Intracellular
Parasites
They need a
HOST CELL
in order to
replicate.
They can be
classified
3 Ways:
Polyhedron,
Helical,
Complex
INTERESTING
SHAPES!
Some are
“enveloped”
with a membranelike structure
Their nucleic
acid type:
Either DNA or
RNA virus
DNA virus:DNA is
inserted into cell,
then protein
synthesis using
virus mRNA
Virus DNA
joins host cell
DNA and
replicates with
host cell DNA
OR,
RNA Virus:
virus RNA is
inserted into
host cell,makes
proteins directly
OR, RNA retrovirus:
DNA, made by
reverse transcription,
joins host DNA,
followed
by protein synthesis
Classified
by whether or
not the virus is
disease-causing
Virus can be
“virulent”--causes
disease right away
(like a cold or
flu)
If virulent,
they undergo
the
LYTIC CYCLE
Lytic Cycle:
1) Adsorption:
virus attaches
to host cell
2) Entry:
virus NA is
injected into
host cell
3) Replication:
Host cell starts
making virus
parts
4) Assembly:
virus parts get
put together
5) Release:
host cell gets so
full of new viruses
that it bursts,
releasing viruses
Virus can be
“temperate”--waits
to cause disease
later
(like HIV)
a) If temperate,
virus goes into
the LYSOGENIC
CYCLE
b) LYSOGENIC
CYCLE:
Starts like lytic
cycle with
adsorption & entry
c) Then,
Attachment:
virus DNA joins
with host DNA
d) Replication:
Host cell
undergoes
replication; virus
DNA gets copied
e) Activation:
something
triggers the
virus to become
virulent (lytic)
Then,it starts
the LYTIC
CYCLE and
causes
infection (disease).
How are viruses
spread?
Bodily fluids
Through air, water
Direct contact
What is smaller
than a virus?
Viroid--NA only
cause plant
diseases
Prion--small
strand of amino
acids; mammal
diseases like CWD
or Mad Cow disease
How could you
prevent viral
infections?
Vaccinations
Wash hands!
Cover your mouth when
sneezing or coughing!
Safe sex!