Viruses
are
not
____________________
,
so
they
are
not
really
living
things
.
They
cannot
carry
out
any
vital
functions
.
They
are
____________________
and
they
infect
____________________
cells
.
They
can
reproduce
.
They
are
parasites
because
they
always
need
a
host
.
These
are
some
of
their
main
characteristics
:
·
They
are
very
____________________
.
We
can
only
observe
them
under
an
electronic
microscope
.
·
The
are
unable
to
____________________
,
so
they
have
no
legs
,
flagellum
or
cillium
.
·
Their
____________________
is
very
extensive
.
They
can
be
found
on
the
ground
,
in
the
air
and
in
the
water
.
Viruses
are
very
simple
microorganisms
.
They
have
only
3
parts
:
·
____________________
acid
:
It
is
the
genetic
material
,
protected
by
a
capsule
.
·
____________________
:
It
is
a
____________________
made
of
proteins
that
covers
and
protects
the
genetic
material
.
It
can
have
different
shapes
.
Viruses
like
____________________
have
a
round
shell
.
·
Viral
____________________
:
It
covers
the
capsid
,
but
not
all
viruses
have
one
.
Only
especial
viruses
like
influenza
or
AIDS
are
covered
by
this
particular
shell
.
The
infection
process
stars
when
the
virus
enters
the
cell
.
Then
the
virus
starts
the
____________________
process
,
creating
viral
components
from
its
genetic
material
.
Later
,
the
viral
components
____________________
and
a
new
virus
comes
out
from
the
cell
.
