Cloning & Genetic Engineering

D. Crowley, 2007

Cloning & Genetic Engineering• To understand cloning and genetic engineering

Friday, April 21, 2023

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 CloningOther 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 & ConsAdvantages 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 & ConsAdvantages 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?