CRISPR,
the
latest
gene-editing
tool
in
modern
biological
research,
is
heralded
as
one
of
the
greatest
biomedical
discoveries
of
this
decade.
Up
until
the
discovery
of
CRISPR,
gene-editing
was
a
difficult
process.
Editing
genes
in
a
cell
(and
hence
an
organism)
requires
the
ability
to
make
cuts
at
precise
points
along
the
DNA
of
that
cell
(for
example,
the
beginning
and
end
of
a
gene
to
replace
that
gene
with
a
differ-
ent
version).
Before
CRISPR,
existing
molecular
techniques
utilized
proteins
that
did
not
allow
scientists
to
cut
at
specific
sequences
of
their
choosing.
Genetic
modifica-
tion
was
therefore
difficult,
inaccurate,
and
limited.
CRISPR
on
the
other
hand,
uses
short
DNA
sequences
embedded
in
proteins
to
recognize
target
DNA
sequences
to
make
cuts.
Reprogramming
DNA
sequences
to
target
another
DNA
sequence
of
your
choice
is
extremely
easy
–
simply
a
matter
of
rearranging
the
nucleotides
(A,
T,
G,
C).
In
effect,
CRISPR
allows
scientists
to
choose
the
exact
location
within
the
DNA
to
make
cuts,
thus
making
genetic
modification
easy,
accurate,
and
extremely
versatile.
CRISPR
can
be
used
to
treat
genetic
diseases
and
cancer,
develop
new
drugs,
create
organs
for
transplant,
and
modify
foods.
In
this
activity,
the
lines
on
the
chromosomes
separating
each
gene
represent
unique
DNA
sequences.
In
order
to
modify
a
gene
in
an
embryo
by
replacing
an
al-
lele
with
a
different
one,
the
cuts
made
in
the
embryo
chromosome
must
match
the
edges
of
the
replacement
allele
exactly
(represented
by
the
shapes
of
the
lines
here).
Hence,
the
alleles
gathered
from
cutting
apart
the
chromosomes
inside
can
be
used
to
identify
the
exact
"sequence"
where
the
original
chromosomes
will
need
to
be
cut
to
replace
the
original
allele
with
the
new
one.
In
this
manner,
a
dragon
embryo
which
has
no
horn
(hh
=
horn
absent)
can
be
genetically
modified
via
CRISPR
to
a
dragon
with
a
horn
present
(Hh
=
HORN
PRESENT).
+
ward
'
s
science
Dragon
Genetics
Background:
