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  • What is a protein? We often think about

  • protein as a nutritional requirement. You

  • eat meat because it has a lot of protein.

  • But proteins are far more than just food.

  • Proteins are made of a string of smaller

  • building blocks called amino acids. Amino

  • acids are kind of like Legos that can be

  • used to build proteins with different

  • structures. When we eat our food, we break

  • down the proteins that we ate into amino

  • acids and then we stick them back

  • together again to make lots of different

  • types of proteins to do jobs in the cell.

  • Here are some things that proteins can

  • do: detect light, form hair, and fight

  • disease. Let's look more closely at three

  • examples. One: proteins move you. The

  • reason that meat has a lot of protein is

  • that meat is muscle. Muscle has to

  • contract to move our body, so it's full

  • of a type of protein that moves stuff

  • around. Let's see how that works: here are

  • some proteins in the muscle fiber. This

  • protein, called myosin, can change its

  • shape. When it changes shape, it moves

  • these fibers relative to one another.

  • Millions of these tiny movements cause

  • the whole muscle to contract.

  • Two: proteins can kill you. Botox is a protein

  • that cuts up molecules in nerve cells

  • that control your muscles. This means

  • that Botox makes your muscles relax. This

  • can be handy to reduce wrinkles for

  • Hollywood actors, but it's not so great

  • with the muscles controlling your lungs

  • stop working after you eat food

  • contaminated with botulism.

  • Three: proteins speed things up. Enzymes are

  • proteins that make reactions go more

  • quickly. For example, the enzyme amylase

  • helps break down starch into sugar. You

  • have amylase in your saliva. Try

  • chewing a piece of bread for a really

  • long time. Keep chewing! What do you notice?

What is a protein? We often think about

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