Genetic Engineering

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22 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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Genetic Engineering

Think of the possibilities

http://channel.nationalgeographic.com/seri
es/explorer/4828/Overview#tab
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Videos/09346_00


Selective Breeding

Selective Breeding

Selective breeding

allows only those
organisms with
desired

characteristics
to produce the next generation.

Nearly all domestic
animals

and most
crop
plants

have been produced by
selective breeding.

Example: Champion race horses,
cows with tender meat, large oranges
on a tree.


Selective Breeding


Artificial selection
-

where individuals
with desirable traits are mated to
produce offspring with those traits.


Hybridization


Hybridization

is the crossing of
dissimilar
individuals to bring together
the best of both organisms.

Hybrids
, the individuals produced by
such crosses, are often hardier than
either of the parents.


Inbreeding



Inbreeding

is the continued breeding
of individuals with
similar

characteristics.

Inbreeding helps to ensure that the
characteristics

that make each
breed

unique will be
preserved
.

Serious
genetic problems

can result
from excessive inbreeding.


WHY?

Inbreeding and Variation

Recessive genetic disorders can be
blindness
, or joint deformities.

Variation

is a term used to identify the
difference

between individuals of a
species
.

For example: Some humans have blond
hair and some have brown. This is a
variation among humans.

Finches
-

Increasing Variation


Why might breeders try to induce mutations?

Breeders increase the
genetic variation

in a
population by inducing
mutations
.



Producing New Kinds of Bacteria

Introducing mutations has allowed scientists to
develop

hundreds of
useful

bacterial strains,
including
bacteria

that can clean up oil spills.


Genetics Engineering

In
genetic engineering
, biologists make
changes

in the
DNA

code of a living organism.

How do scientists make changes to DNA?

Scientists use different techniques to:

extract

DNA from
cells

cut

DNA into smaller
pieces

identify the sequence of bases in a DNA
molecule

make unlimited copies of DNA


The Tools of Molecular Biology

Each
restriction enzyme

cuts DNA at a specific
sequence of nucleotides.

How do scientists manipulate DNA

1. DNA is removed from
the cell of an
organism

2. DNA is cut using
restriction enzymes to
identify the bases.

3. There are thousands of
restriction enzymes,
each cuts the DNA at
a different starting
place based in the
nucleotide sequence.

4. DNA fragments are
separated by gel
electrophoresis.

5. Positive charged DNA
moves to negative poles
and negative DNA moves to
positive poles. Smaller
fragments move faster,
larger move slower.

6. This is also how DNA is
compared (ex at crime
scenes)

7. Then, unlimited copies of
fragments are made by
scientist.


Nova: who done it

http://www.pbs.org/wgbh/nova/sheppard/analyze.html





Video clip

Video clip 2

Cell Transformation

13
-
3

Cell Transformation

Recombinant DNA

Host Cell DNA

Target gene

Modified Host Cell DNA

Cell Transformation

During
transformation
, a cell takes in DNA from
outside the cell. The
external

DNA becomes a
component

of the cell's DNA.

Foreign

DNA is first joined to a small,
circular

DNA molecule known as a
plasmid
.

Plasmids are found
naturally

in some
bacteria

and have been very useful for DNA transfer.

The plasmid has a
genetic marker


a gene that
makes it possible to
distinguish

bacteria that
carry the plasmid (and the foreign DNA) from
those that don't.





Biotechnology and genetic engineering


Genetic engineering is making
changes

in the
DNA code of a living organism.

A scientist can take
genes

from one organism
and
transfer

them to another organism. This is
called
transformation
.

Genetic engineering has given rise to a new
technological field called biotechnology
(technology of life).

The organisms that have DNA transferred to
them are called transgenic.

(trans: means different, genic: refers to genes)

Transgenic helpful?

How are transgenic organisms useful to human
beings?

Transgenic bacteria produce important
substances useful for health and industry.
Transgenic bacteria have been used to produce:


insulin


growth hormone


clotting factor




Copyright Pearson Prentice
Hall



Recombinant
DNA

Gene for human
growth hormone

Gene for human
growth hormone

Human Cell

Bacteria cell

Bacterial
chromosome

Plasmid

Sticky
ends

DNA
recombination

Bacteria cell
containing gene for
human growth
hormone

DNA
insertion

..
\
Genetic engineering
\
1 gen mod insulin
wit res enz.wmv

http://www.youtube.com/watch?v=8rXizmL
jegI

Animals and plants

Transgenic animals: genes inserted into
animals so they produce what humans need.

A way to improve the food supply: livestock
given genes that make them grow faster or resist
bacteria that cause infections.

Mice are given human genes that make their
immune system work like ours. They can now
be used for researching the human immune
system

Transgenic Plants

Transgenic plants: plants are given genes
that make them produce a natural
pesticide. Now they don’t have to be
sprayed with cancer causing pesticides.

25% of all corn is like this. It called
genetically modified or GM.

Cloning

Cloning

A
clone

is a member of
a population of
genetically
identical

cells produced from a
single cell
.

In 1997, Ian Wilmut
cloned a sheep called
Dolly
.

Dolly and Bonnie

Cloning

Donor Nucleus

Fused cell

Embryo

Egg Cell

Foster Mother

Cloned
Lamb

Cloning

1.
A single cell is removed from a parent
organism.

2.
An entire individual is grown from that
cell.

3.
Remember one cell has all the DNA it
needs to make an entire organism.

4.
Each cell in the body has the same DNA,
but cells vary because different genes
are turned on in each cell.


Dolly

Dolly was the first animal cloned.

She had the same exact DNA as
her mother and had no father.

Cloning is a form of asexual
reproduction.

Since Dolly, cats and other
organisms have been cloned.

The cat that was cloned had the
same exact DNA but different
color fur than the mother.

How can this be?

Environment plays a huge part
in the way organisms develop.


http://content.tutorvista.com/biology_11/content/media/cloning.swf


..
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Genetic
engineering
\
Bonehead_Detectives_of_the
_Paleoworld__The_Dino_Clones.wmv

Cool cloning vids

Cloning the dead
http://videos.howstuffworks.com/hsw/6365
-
cloning
-
the
-
dead
-
video.htm

Ethics of human cloning:
http://videos.howstuffworks.com/hsw/6362
-
the
-
ethics
-
of
-
human
-
cloning
-
video.htm

Creating a superhuman race:
http://videos.howstuffworks.com/hsw/6348
-
could
-
cloning
-
create
-
a
-
superhuman
-
race
-
video.htm

Positives of cloning:
http://videos.howstuffworks.com/hsw/6363
-
cloning
-
and
-
human
-
reproduction
-
video.htm

Cloning endangered species:
http://videos.howstuffworks.com/hsw/6364
-
cloning
-
and
-
the
-
protecting
-
endangered
-
species
-
video.htm

Cloning for organ transplants:
http://videos.howstuffworks.com/hsw/6359
-
cloning
-
organs
-
for
-
transplant
-
video.htm






Human Genome

Human Chromosomes

Human Chromosomes

Cell biologists analyze chromosomes by looking at
karyotypes
.

Cells

are
photographed

during
mitosis
. Scientists
then cut out the
chromosomes

from the
photographs and group them together in pairs.

A
picture of chromosomes
arranged in this way is
known as a
karyotype
.


Human
Karyotype


Human Traits


Pedigree Charts


A
pedigree

chart shows the
relationships

within a
famliy
.

Genetic counselors analyze pedigree charts to
infer the genotypes of family members.


Human Traits

A circle
represents

a female.

A horizontal line
connecting a
male and a
female
represents a
marriage.

A shaded
circle or
square
indicates
that a person
expresses
the trait.

A square
represents

a male.

A vertical line and a
bracket connect the
parents to their
children.

A circle or square
that is not shaded
indicates that a
person does not
express the trait.

Human Genes

Blood Group Genes

Human blood comes in a
variety

of genetically
determined blood groups.

A
number

of
genes

are responsible for human
blood

groups.

Human Genes

Recessive Alleles

Many disorders are caused by autosomal
recessive

alleles.

Copyright Pearson Prentice
Hall

Human Genes

From Gene to Molecule

Sickle Cell Disease

Sickle cell
disease is a
common genetic disorder
found in African Americans.

It is characterized by the bent
and twisted shape of the
red blood
cells.

Sex
-
Linked Genes

Sex
-
Linked Genes

The
X

chromosome and the
Y

chromosomes
determine sex.

Genes located on these chromosomes are
called
sex
-
linked genes
.

More than
100
sex
-
linked genetic disorders have
now been mapped to the
X

chromosome.

Sex
-
Linked Genes

The
Y

chromosome is
much smaller than the X
chromosome and appears
to contain only a few
genes.


Sex
-
Linked Genes


For a recessive allele to be expressed in
females, there must be two copies of the
allele, one on each of the two X
chromosomes.

Males have just one X
chromosome. Thus, all X
-
linked
alleles are expressed in males,
even if they are recessive.


Chromosomal Disorders


The most common
error

in
meiosis

occurs when
homologous chromosomes
fail

to
separate
.

This is known as
nondisjunction
, which means,
“not coming apart
.”

If
nondisjunction

occurs,
abnormal

numbers of
chromosomes may find their way into gametes, and
a disorder of chromosome numbers may result.


Chromosomal Disorders

Down syndrome
produces mild to
severe mental
retardation.

It is characterized
by:

increased
susceptibility to
many diseases

higher frequency of
some birth defects


Down Syndrome Karyotype

The Human Genome Project

A
genome

is
all

the
DNA

in one cell of an
organism.

The main goal of the Human Genome
Project was to
identify the DNA sequence
of every gene in the human genome. It
was completed in May 2006.

Scientists estimate that human DNA has
around 25,000 genes.

Gene Therapy



In
gene therapy
, an absent or faulty gene is
replaced

by a normal,
working

gene.


The body can then make the correct protein or
enzyme, eliminating the cause of the disorder.

Copyright Pearson Prentice
Hall

Gene Therapy

Viruses

are often
used because of
their ability to enter a
cell’s
DNA
.

Virus particles are
modified so that they
cannot cause
disease.

Copyright Pearson Prentice
Hall

Gene Therapy

A
DNA

fragment containing a
replacement

gene

is spliced to viral DNA.