Biology Genetic Engineering Gel Electrophoresis - colombobiology

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Dec 14, 2012 (8 years and 10 months ago)

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Biology

Genetic

Engineering

Gel
Electrophoresis

Juliana Machado


Isabella

Rojas


Gabriel Felipe Galvis


Genetic

Engineering


Also

called

genetic

modification
.


I
s

the

human

manipulation

of

an

organisms

genome

(
hereditary

information

of

the

organism
)

using

modern

DNA

technology
.


It

involves

the

introduction

of

DNA

or

synthetic

genes

into

the

organism
.


History



Humans

have

altered

the

genomes

of

species

for

thousands

of

years

through

artificial

methods
.

Genetic

engineering

considered

the

direct

manipulation

of

DNA

by

humans

has

only

existed

in

1970
s
.


Paul

Berg

created

the

firsr

recombinant

(

DNA

sequences

that

result

from

the

use

of

laboratory

methods
)
.

By

combining

the

monkey

virus

SV
40

with

lambda

phage

(
another

virus

consisting

of

a

head)









Herbert and Stanley Cohen
created

the

first

transgenic

organism

by

inserting

antibiotic

resistance

genes
into

the

plasmid

of
an

E.
Coli

bacterium
.


Rudolf

Jaenisch

created

a

transgenic

mouse

by

introducing

DNA

into

its

embryo
,

making

it

the

first

transgenic

animal
.




In

1976
,

Genentech
,

the

first

engineering

company

was

founded

by

Herbert

Boyer

and

Robert

Swanson
.




Applications


Genetic

engineering

has

applications

in

medicine,

research
,

industry

and

agriculture
.


Medicine
:

Genetic

engineering

has

been

used

to

produce

insulin
,

human

growth

hormones
.

Also

it

is

used

to

create

animal

models

which

are

non
-
human

animals
,

used

during

the

research

and

investigation

of

human

diseases
.

Genetically

modified

mice

are

the

most

common

genetically

engineered

animal

model
.





Research
:

Genetic

engineering

is

an

important

tool

for

natural

scientists
.

Genes

and

other

genetic

information

from

a

wide

range

of

organisms

and

information

are

transformed

into

bacteria

for

storage

and

modification
,

creating

genetically

modified

bacteria

in

the

process
.

Also

o
rganisms

are

genetically

engineered

to

discover

the

functions

of

certain

genes
.

This

could

be

the

effect

on

the

phenotype

of

the

organism
,

where

the

gene

is

expressed

or

what

other

genes

it

interacts

with
.



Industry
:
By

engineering

genes
it

is

possible

to

create

a
biological

factory

that

can produce
proteins

and
enzymes
. Bacteria and
yeast

have

been

used

to

produce medicines
such

as
insulin
, human
growth

and
vaccines

(
biological

preparation

that

improves

immunity

to

a particular
disease
).




Agriculture
:

Genetic

engineering

is

used

in

the

creation

of

genetically

food
.

Genetically

modified

organisms

have

had

specific

changes

introduced

into

their

DNA

by

genetic

engineering

techniques
.

These

techniques

are

much

more

precise,

an

example

is

mutagenesis

(
mutation

breeding
)

where

an

organism

is

exposed

to

radiation

or

chemicals

to

create

a

non
-

specific

but

stable

change
.

Other

techniques

by

which

humans

modify

organisms

include
:

selective

breeding
,

plant

breeding

and

animal

breeding
.

Since

genetically

modified

food

has

been

introduced

into

supermarkets
,

there

has

been

much

controversy
.



What

is

Gel
electrophoresis
?


When

DNA

manipulation

began
,

DNA

fragments

were

separated

by

gravity
.

In

the

1970
s,

the

powerful

tool


of

DNA

electrophoresis

was

developed
.


Gel

electrophoresis

in

chemistry
:

Is

a

method

used

to

separate

proteins

by

charge

and


size


Gel

electrophoresis

in

biochemistry
:

In

molecular

biology

it

is

used

to

separate

DNA

and

RNA

fragments

by

length
,

to

estimate

the

size

of

DNA

and

RNA
.




Electricity

effects

on

molecules



Nucleic

acids

molecules

are

separated

by

using

a

electric

field

to

move

the

negatively

charged

molecules

through

an

agarose

matrix


We

need

to

take

into

account

that

s
horter

molecules

move

faster

and

migrate

longer

than

longer

ones

because

shorter

molecules

migrate

more

easily

through

the

pores

of

the

gel
.

This

process

is

called

sieving
.

is

a

simple

and

convenient

technique

of

separating

particles

of

different

size


In

the

case

of

proteins

they

are

separated

by

charge

in

agarose

becuase

the

pores

of

the

gel

are

too

large

to

sieve

proteins

Also

electrophoresis

can

be

used

in

the

separation

of

nanoparticles
.


Agarose


Agarose

is

a

polysacharide

obtained

from

agar

that

is

used

for

a

variety

of

science

applications
,

specially

in

gel

electrophoresis
.



Agarose

it

is

used

in

t
he

matrix
,

which

plays

a

vital

role

in

this

separation
.


Agarose

used

as a
gel
to

be
incluided

in
the

matrix
.

How

does

gel
electrophoresis

work
?

-
After

DNA

is

extracted

from

cells

or

obtained

using

PCR

(
polymerase

chain

reaction
),

they

are

cut

into

many

fragments

of

different

lenghts

with

restriction

enzymes

(
enzyme

that

cuts

DNA)
.







-
DNA

fragments

are

loaded

into

the

wells

of

an

agarose

gel

and

placed

in

an

electrophoresis

buffer

filled

tank
.

This

gel

which

is

similar

to

gelatin

is

formed

for

the

DNA

fragments

to

be

placed

in

here
.






-
This

gel

is

placed

in

the

matrix

and

contains

electrolytes
,

so

that

an

electric

current

conducted
.


-
Positive

and

negative

electrodes

are

connected

to

the

opposite

ends

of

the

gel
-

(
electric

field

is

applied
)
.


-
The

negatively

charged

DNA

fragments

are

drawn

towards

the

positive

terminal
.







The

agar gel
is

highly

porous



Shortest

DNA
fragments

are
able

to

move

quickly

through

the

pores
.


Larger

DNA
fragments

move

very

slowly

because

it

is

more
difficult

for

them

to

pass

through

the

pores
.


Applications

of Gel
electrophoresis


Estimation

of

the

size

of

DNA

molecules
.

Example
:

restriction

enzyme

(
enzyme

that

cuts

DNA)

also

called

restriction

mapping

of

cloned

DNA
.



Analysis

of

PCR(
polymerase

chain

reaction
)

products

is

a

scientific

technique

in

molecular

biology

to

amplify

or

increase

a

single

or

few

copies

of

a

piece

of

DNA

across

several

orders
,

generating

thousands

or

millions

of

copies

of

a

particular

DNA

sequence
.


8 PCR
tubes
,
each

containing

a
reaction

mixture

What

is

DNA
profiling
?


DNA

profiling

also

called

DNA

fingerprinting
,

DNA

testing
,

is

a

technique

use

by

forensic

scientists

to

distinguish

between

individuals

of

the

same

species

using

samples

of

their

DNA
.



Although

the

majority

of

our

DNA

is

the

same
,

there

are

short

pieces

called

microsatellites

.

These

repeat

many

times

in

a

persons

DNA
.

This

is

the

pattern

of

repeats

which

is

different

in

every

individual
.



Knowing

these

microsatellites
,

DNA

sequences

are

the

basis

for

the

DNA

profiling
.



Stages

of DNA
profiling



STEP 1:
Cells

are
broken

down

to

release

DNA.
If

a
small

amount

of DNA
is

available
,
the

amount

can be
increased

or

amplified

by

using

polymerase

chain

reaction

(PCR).


STEP

2
:

The

DNA

is

cut

into

fragments

using

restrictions

enzymes

as

I

explained

before
.

Each

restriction

enzyme

cuts

DNA

at

a

specific

base

sequence
.



The

sections

of

DNA

which

are

cut

are

called

restriction

fragments
.








STEP 3:
In DNA
profiling

the

gel
electrophoresis

is

involved

Fragments

are
separated

on

the

basis

by

using

a
process

called

gel
electrophoresis
.



DNA
fragments

are
inserted

in
the

wells

and a
electric

current

is

developed
. As I
explained

before

in gel
electrophoresis
.


DNA
is

negatively

charged

so
it

is

attracted

to

the

positive
part

of
the

gel.


DNA
is

separated

on

the

basis

of
size
.


A
radioactive

is

added

which

combines
with

the

DNA
fragments

to

produce a
image
,
that

contains

the

copies of
DNA
bands
.


STEP 4:
The

pattern

of
the

fragment

is

analyzed
.


USES OF DNA
PROFILING


DNA
profiling

is

used

to

solve

medical
problems
.


Biological

uses
for

DNA
profiling
:

-
Blood


-
Hair

-
Saliva

-
Body

tissue

cells



Bibliography



http://science.howstuffworks.com/dna
-
profiling1.htm


http
://learn.genetics.utah.edu/
search


http://www.sumanasinc.com/webcontent/animation
s/content/
gelelectrophoresis.html


http://www.youtube.com/watch?v=
QEG8dz7cbnY