Page 76. Watch the Lecture. Part B. LISTEN FOR MAIN IDEAS

Unit eight

page 76

watch the lecture

part B: listen for main ideas

alright my friends, today were going to continue with our discussion of genetic modification.

Now, does everyone remember our definition?

Yes, no, were not sure…

okay let’s recap.

genetic modification is when we change the genes inside of a living thing to make it grow in a different way, okay?

Alright, today were going to talk specifically about genetically modified food or GM food for short.

genetic modification has produced many new possibilities in plant biology.

scientists have been able to create all kinds of new plants and it’s really a very exciting time in this field.

but there are some people who are against this practice, we’ll talk more about that later.

right now, we’re going to look at three types of genetic modification.

First, modifications to make stay fresh longer.

Second, modifications to make crops grow better.

and third, modifications to make food healthier.

our first example is about a modification made to help food retain freshness longer; it was called “the FLAVRSAVR tomato”, that spelled FLAVRSAVR, Flavrsvr.

like the name says, it was supposed to save the flavor of a fresh tomato.

It is interesting actually because it was the first genetically modified food to be sold in US supermarkets back in 1994.

So, why was this tomato created?

well there’s a big problem with growing fruits and vegetables and that’s keeping them fresh.

like tomatoes at you pick them, they go bad quickly.

they get too soft, they don’t taste good anymore.

now the reason the tomato goes bad, is because of the special chemical inside the tomato plant.

this chemical starts to work after a tomato was picked; starts making it get soft.

scientists wanted to stop this chemical from working; to do this, they created the FLAVRSVR tomato.

by adding the gene called antiscnsc RNA; that ANTISCNSC. this antiscnsc RNA gene stops the chemical that makes tomatoes get soft.

the chemical doesn’t function, so the tomato stays fresh for a long time, much longer than a normal tomato.

but there were some problems with the FLAVRSVR tomato.

one problem was that people didn’t trust this new genetically modified food; they thought it might be unhealthy or even dangerous to eat, so they didn’t buy it.

another problem was that, people said it just didn’t taste very good.

at anyway, shoppers didn’t purchase the FLAVRSVR; so it wasn’t grown anymore after 1997.

our next example is a plant that was developed to grow more easily; a type of corn called BT corn; that’s BT corn.

Now, all farmers have problems with insects eating the crops and corn farmers have problems with the insect called the root worm.

this one gets inside the corn plant and it eats it and these worms can kill an entire corn crop.

For a long time the only method for getting rid of these insects was the use of pesticides.

but as you know, pesticides cause problems too; because while they do kill pests, they also can be dangerous to people and the environment, and they’re very expensive to use; so it isn’t the best solution to the problem.

and this is why BT corn was developed; to make BT corn, scientists use the common bacteria called BT bacteria.

this bacteria lives in the ground and makes a natural poison that kills insects, but it doesn’t hurt people at all.

so scientists added the BT gene to corn plants and now when insects consume the plant, they die but people and animals aren’t hurt at all.

now for farmers, BT corn is one of the most popular genetically modified crops today; it’s grown all over the world.

although the corn is used primarily as food for animals.

Finally, let’s look at a food that’s been created to solve a health problem.

millions of people around the world, the poorest people they don’t get enough food with vitamin A.

you know the vitamin and orange foods like carrots and sweet potatoes.

and this causes serious health problems.

over a million children die each year the lack of vitamin A and another 300,000 go blind.

so scientists thought if they could add vitamin A to rice it would help millions of people eat better and live healthier lives.

they came up with a new kind of rice with extra vitamin A in it. it’s called “golden rice”.

to make golden rice, scientists took a vitamin A gene from a plant; a daffodil, which is a flower and added this gene to the rice plant.

looking at the rice, that looks just like regular rice.

except it has a kind of yellowish orange, golden color like a carrot.

that’s the vitamin A gene giving that orange color.

at this point, golden rice is still being studied to make sure it’s safe.

So, it’s been grown in a few places as a part of these studies, but we’ll have to see if it becomes a common source of vitamin A in the future.

so that gives you some ideas of the three main reasons why genetically modified plants have been developed; next time, were going to look at exactly how this works in more detail.