homework encyclopedia

210 Science and Technology

Genetic engineering is the manipulation of genes of

living things. Scientists can now insert genes from

one organism into another. They do this to grow

. GM FOOD. They can also. CLONE embryos that

provide. STEM CELLS to repair damaged body tissue.

HOW CAN WE MANIPULATE GENES?

When dog breeders select puppies with short tails to

breed from, they are manipulating the gene for tail

length. The gene for short tails is passed on, and the

gene for long tails dies out. Now, scientists can select

and move genes between organisms in the laboratory.

A gene for disease resistance can be “snipped out”

from the DNA of one plant and inserted into another.

WHAT WAS THE GREEN REVOLUTION?

In the 1960s, scientists tried to breed crops suited to

conditions in developing countries. The aim was to

reduce food shortages by introducing productive crops

that were disease-resistant. In India, crop production

increased, but in other places, the new crop varieties

needed fertilizers that farmers could not afford.

ARE GM CROPS SAFE?

Some farmers are not keen to grow GM crops. One

worry is that genes introduced into the crop will

transfer to other species. Another concern is that

herbicide- and pesticide-resistant crops encourage

farmers to use too many of these chemicals, which

might damage wildlife.

The first genetically modified (GM) food went on sale in 1994.

It was a variety of tomato called Flavr Savr. The gene that makes

the tomato soften had been changed to make it ripen more slowly,

so that it would develop more flavour.

WHAT IS GENETIC VARIATION?

The differences between species and between

individuals are explained by the differences in

their genes. Sexual reproduction, which randomly

mixes genes from parents in their children, produces

variation from generation to generation.

Genetic Engineering

4 GM OR NOT?

GM crops, such as these

tomatoes, look just like

traditional varieties. The changes

produced by gene manipulation

are subtle. Genetic modification

is more likely to be used to affect

the crop’s disease resistance or

shelf life than its appearance.

GENETICALLY MODIFIED

PLANT  3

This GM seedling has had genetic

material from another species

inserted into its genetic code.

Scientists perform genetic

modification on plants to make

them more resistant to disease,

pests, pesticides, and even bad

weather conditions.

GM FOOD

MICROBE COLONY 1

Genetic engineering is commonly

performed on microbes grown in

the laboratory, such as on this

fungus. Genes are inserted into

microbes to make them produce

substances to treat disease.

Soil

with natural

nutrients

GM seedling

tolerates

pesticides and

herbicides

genetic

engineering