3.10 More Mutations

A. Editing With Nature

Mutations happen when mistakes are made while our DNA is being copied. But what if we could use nature to make changes to DNA.

 

Think About It: What do you notice is similar or different between the three images below.

poodle

golden retriever

golden doodle

Golden doodles are a special breed. When you have one parent as a poodle and one as a golden retriever their offspring are golden doodles.

 

Breeding happens when people put two parents together so that they can create offspring that have traits from both parents. Dog breeders keep breeding until they get dogs that have the exact traits they want.

 

Sizes of Dogs

 

Dogs can even be bread for size. You can already buy dogs of different sizes that have been bred to give you you perfect size pet. For example, goldend oodles often come in four sizes.

toy

mini

medium

large

B. Cross Species Breeding

Sometimes people can even breed different species if they are very close together. A mule is a cross between a horse and a donkey. The mule is infertile, though. That means it cannot reproduce or have offspring. 

 

Think About It?

  • What do the mule, horse and donkey have in common? How are they different? 
  • Should We: If breeding is natural – should it be allowed? Why?
horse

donkey

mule

C. Mutations in People

Remember Jude, who has hemophilia?

Hemophilia is caused by a mutation in a gene that helps your blood clot.
Normally, your body makes special proteins that stop bleeding when you get a cut. But in people with hemophilia, a mutation changes the instructions for making one of those proteins. 

 

Because the protein doesn’t work properly (or isn’t made at all), the blood can’t clot like it should—so even small injuries can lead to longer bleeding.

This mutation is passed down from parents to offspring. People aren’t bred like dogs, but when two parents have a child, their DNA is passed down to their children. If there is a mutation in their DNA that mutation can be passed on to their offspring. That’s how DNA is passed from person to child.

D. Other Natural Mutations

Mutations don’t just cause disease. They can cause other visible changes. Ever heard of “double-muscled” animals? It’s not just a nickname—some animals really do grow way more muscle than usual! 

 

This happens because of a change (mutation) in a gene called MSTN. The MSTN gene gives instructions for making myostatin, a protein that tells the body when to stop building muscle. But when there’s a mutation in this gene, the body makes less myostatin—and that means muscle growth doesn’t stop like it should.

H5P: Slide Show – What do you think happens to animals with mutation on the MSTN gene and they don’t have enough protein to signal the body should stop building muscle?

Think About It:

Should We: Is it right to breed animals with mutations to build super strong cows? If we could, should we give that mutation to people?

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