clones

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14 Δεκ 2012 (πριν από 4 χρόνια και 6 μήνες)

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Cloning & Genetic
Engineering

D. Crowley, 2007

Cloning & Genetic Engineering


To understand cloning and genetic engineering

Sunday, March 17, 2013

Cloning


What is a clone? Is it natural?



Exact copies of organisms are called
clones

-

they have identical
genetic information

as the organism they were cloned from



Cloning is the
production of genetically identical copies



Clones frequently occur naturally, but they can also be produced
artificially

Natural Cloning


Plants are easy to clone
-

gardeners often take cuttings to grow new
plants which are clones


Cloning is an example of
asexual

reproduction (where
genetic information

comes from just one parent)



Potato plants reproduce vegetatively by
growing tubers, from which the new plant will
grow these are clones

Natural Cloning

Other examples include:
-



A colony of bacteria
-

each bacterium splits into two, with the total
number doubling every twenty minutes
-

all genetically identical



A clump of daffodils
-

the new plants arising from the original bulb are
exact replicas or clones of the parent (and of each other)



Strawberry or blackberry runners are clones of the parent plant.

Artificial Plant Cloning


Clones can also be produced artificially
-

you can take a small number of
cells from a 'parent' plant and ‘grow’ them in a medium rich in nutrients
and plant growth hormones

Plants Pros & Cons


Cloning of plants is very important commercially
-

successful varieties of
plants can be produced on a large scale in a short space of time



Can you think of any pros / cons of
plant

cloning?

Advantages of plant cloning

Disadvantages of plant cloning

Plants Pros & Cons

Advantages of plant cloning

Disadvantages of plant cloning

Lots of new plants can be grown in
a short time period

All plants have the same genetic
information
-

all are vulnerable to
the same disease / pest

Conditions can be precisely
controlled

No new beneficial characteristics
will arise (as they do by chance
naturally)

All new plants get the
characteristics you want
-

e.g.
disease resistant

No variation causes the
gene pool
(no. of genes in a population) to be
reduced

Artificial Animal Cloning


Artificial cloning of animals is now commonplace in laboratories: the
most famous example of animal cloning is
Dolly

the sheep:
-

1.
An egg cell was removed from the ovary of an adult
female sheep, and the nucleus removed


2.
The empty egg cell was fused with DNA extracted
from an udder cell of a donor sheep


3.
The fused cell now began to develop normally, using
the donated DNA


4.
Before the dividing cells became specialised the
embryo was implanted into the uterus of a foster
-
mother sheep
-

the result was Dolly,
genetically
identical

to the donor sheep.

Animals Pros & Cons


Animal cloning has potential uses in both farming and medicine (for
protein synthesis (manufacturing proteins), gene therapy (adding /
replacing specific genes to treat diseases) and organ donation (e.g.
kidneys from pigs which can be used in humans))



Can you think of any pros / cons of
animal

cloning?

Advantages of animal cloning

Disadvantages of animal cloning

*Interestingly cells seem to ‘know’ their age
-

so a cloned animal, although just born,
on a cellular basis is as old as its donor parent!

Animals Pros & Cons

Advantages of animal cloning

Disadvantages of animal cloning

Allows you to check the embryo for
defects

No new beneficial characteristics
will arise (as they do by chance
naturally)

Allows you to choose the sex and
time of birth

All animals have the same genetic
information
-

all equally vulnerable
to the same disease or predator

Exact copies of the ‘best’ animal
can be made year after year
(selective breeding)

No variation causes the
gene pool
(no. of genes in a population) to be
reduced

Could be used in saving
endangered species from extinction

Animal welfare concerns
-

cloned
animals tend to die young*

Genetic Engineering


Genetic engineering is
very

different from cloning



How did humans used to change the genetic make
-
up of organisms we took
advantage of?



Selective breeding
-

only breeding the organisms with the characteristics we
wanted



Genetic engineering takes genes from one organism, and places them into the
chromosomes of another organism. It alters an organism's genetic code, and
works because there is only one code for life



The set of instructions for which a gene is responsible work whichever organism
the gene is in, e.g. a gene for luminescence from a jellyfish can be added to a
frog, making it luminescent too!

Genetic Engineering


Enzymes are used to cut up and join together parts of the DNA of one
organism, and insert them into the DNA of another organism



In the resulting new organism the inserted genes will code for one or
more new characteristics
-

for example producing a new substance, or
performing a new function


The organism has been
genetically re
-
engineered



E.g. a bacterium's genetic
make
-
up can modified by
splicing a gene into its DNA

Arguments


Genetic modification can be used to help many people
-

e.g. people
suffering from diabetes can get their insulin from genetically modified
bacteria, rather than having to extract it from other humans / animals



Some people believe growing and eating genetically modified plants
could be dangerous because they contain genes which are not natural

Task


Your task

is to produce a poster listing
both

the pros or cons for genetic
engineering
-

it needs to be informative and catchy to highlight both
sides of the argument for people who do not know much about the
subject



Whilst doing think where you stand
-

is genetic modification a good or a
bad thing?