9.4 Genetic Engineering KEY CONCEPT Genetic Engineering is about changing the DNA sequences of organisms

9.4 Genetic Engineering

KEY CONCEPT Genetic Engineering is about changing the DNA sequences of organisms.


Genetic Engineering Technique #1:Entire organisms can be cloned.• A clone is a genetically identical copy of a gene or of

an organism.

CC, short for CopyCat, is the first successfully clonedCat.

The originalcat


• Cloning occurs in nature.

– bacteria (binary fission)– some plants (from roots)– some simple animals (budding, regeneration)


• Mammals can be cloned through a process called nuclear transfer.

– nucleus is removed from an egg cell– nucleus of a cell from the animal to be cloned is

implanted in the egg


One of first mammals to be successfully cloned was a sheep.


The adult sheep is Dolly,

the first mammal cloned

from an adult cell.

The lamb is Dolly’s

offspring, called Bonnie.


• Cloning has potential benefits.

– organs for transplant into humans– save endangered species

• Cloning raises concerns.– low success rate– clones “imperfect” and less healthy than original animal– decreased biodiversity


Genetic Engineering Technique #2: Recombinant DNANew genes can be added to an organism’s DNA.

• Genetic engineering involves changing an organism’s DNA to give it new traits.

• Genetic engineering is based on the use of recombinant DNA.

• Recombinant DNA contains genes from more than one organism.

(bacterial DNA)


• Process involves:– Bacterial plasmids are often used to make

recombinant DNA.

– Steps:

1. plasmids are loops of DNA in bacteria

2. restriction enzymes cut plasmid and foreign DNA

3. foreign gene inserted into plasmid


Genetic Engineering Technique #3: GMO’sA GMO = a “Genetically Modified Organism”

• A “GMO” or transgenic organism has one or more genes from another organism inserted into its genome.


• GMO (Transgenic) bacteria can be used to produce human proteins.

– gene inserted into plasmid – plasmid inserted into bacteria– bacteria express the gene

• GMO (Transgenic) plants are common in agriculture.– transgenic bacteria

infect a plant– plant expresses

foreign gene– many crops are now

genetically modified(GM)


Examples of how transgenic bacteria and plants are being used:

1.1. Transgenic BacteriaTransgenic Bacteria

Now make insulin, growth hormone, and clotting factor cheaply and in great abundance)

2. Transgenic Plants2. Transgenic Plants

52% of soybeans and 25% of corn are transgenic Different varieties are resistant to disease, produce their own insecticide, resist weed-killing chemicals, and/or have increased vitamin content


• GMO (Transgenic) animals are used to study diseases and gene functions.

– Ex. transgenic mice used to study development and disease

– gene “knockout mice” used to study gene function

Knockout mouse on left lacks gene for protein leptin, which helps to control food intake. Used in obesity studies.


• Scientists have concerns about some uses of genetic engineering.

– possible long-term health effects? of eating GM foods– possible effects of GM plants on ecosystems and

biodiversity ?

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9.4 Genetic Engineering KEY CONCEPT Genetic Engineering is about changing the DNA sequences of organisms