DIGEST FOOD
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Digestive System
Digestive enzymes
Proteins called enzymes work in your digestive tract. They break food into pieces small enough
for your body to absorb and use. Different sets of enzymes break down different types of food.
Protein from food
Most living things take in nutrients in some form. From animals to plants to bacteria, we all use proteins to digest our food!
Examples
This protein is called amylase. It breaks down starch.
Carbohydrate (“starch”)
Hair
Hair Root
BUILD HAIR AND NAILS
Keratin builds lots of other things too! Beaks, horns, feathers, scales — and much more — are made mostly of keratin.
Individual keratin proteins twist and weave together to make strong, rope-like fibers.
Hair is made up of dead cells filled with a protein called keratin. New cells are added to the base as the hair grows. Fingernails grow this way too, and they are also made almost entirely of tough keratin proteins.
At the synapse, the sending neuron releasing chemical signals. The signals activate protein receptors on the receiving cell, and that keeps the message going. Once the signal has done its job, a transporter protein takes it back up into the sending cell.
Anything with a brain has similar cells that use many of the same types of proteins. That goes for the simple brain of the water bear to the super-smart brains of the kea, which can do math.
Brain Cells
TRANSMIT MESSAGES IN THE BRAIN
Receiving neuron
Synapse
Sending neuron
In the brain, cells called neurons send and receive messages. It takes a lot of proteins to do this job. Most of the action happens in a synapse. That’s where a neuron that’s sending a signal comes very close to a neuron that’s receiving it.
Electrical impulses travel from one end of a neuron to the other. To send a nerve impulse, the cell needs the right balance of charged ions on the inside and outside. Proteins set up this ion balance, and they help to carry the impulse.
Transporter proteins move ions in and out of the cell, all along its length. When the impulse comes, channel proteins open, and the built-up ions rush through in the opposite direction. This keeps the impulse going.
Nerve impulse
MOVE IONS
Even if they don't send nerve impulses, all cells need to maintain a proper balance of ions. And they use similar proteins to do it — even these single-celled yeast.
These proteins work together like an assembly line to build a pigment called melanin. It's what gives your hair, eyes, and skin their color. Melanin is made inside specialized cells called melanocytes.
In animals, melanin pigments color fur, feathers, scales, and more. And in plants, similar proteins work together to make pigments that color their flowers.
Each protein enzyme carries out one step in the process. It catalyzes a chemical reaction that changes one substance into something else.
Melanocyte
Final product: melanin
BUILD PIGMENTS
Starting material
Nutrients
All living things use proteins to move nutrients into their cells. Plants make nutrients in their leaves and often move them to their roots for storage. Root vegetables, like sweet potatoes, beets, and carrots, hold lots of energy in their roots.
Transporter proteins
Inside of muscle cell
Muscle Cell Membrane
This protein is moving sugar from the outside to the inside of a cell.
Outside of muscle cell
MOVE NUTRIENTS
Nutrients travel through the blood stream to all the body’s tissues. Cells use proteins to grab the nutrients they need and move them inside. Different proteins move different nutrients.
Touch-sensing cell
Touch Sensing Cell
Pressure slightly squishes the touch-sensing cell. This bends the piezo proteins sitting in the cell membrane. As it bends, a hole opens up that lets ions move through. This starts a chemical signal, and other proteins help to carry it.
HELP YOU SEE, TASTE & FEEL
Skin
Proteins that respond to other types of signals contribute to all our senses. Light-sensing proteins in eye cells help with sight. And chemical-sensing proteins in the nose and mouth help with smell and taste.
Touch-sensing cells in your fingers use specialized proteins to help you feel. They turn a signal from outside the body into a chemical signal that goes to your brain.
It may not look quite like your bicep, but scallops use a similar muscle to hold their shell closed. It’s called an adductor, and it works the same way!
Myosin proteins make the movement happen. They walk along the actin proteins, and this shorttens the muscle fiber. Many proteins working together make muscles contract.
Muscle Cell
BUILD & MOVE MUSCLES
Muscles are built mostly from strong protein fibers. Different types of protein fibers line up alongside one another in an organized pattern.
Every known living thing has DNA, from puppies to single-celled bacteria. To copy their DNA, they all use similar teams of proteins.
Polymerase
DNA polymerase puts building blocks together to make a new DNA strand.
Original DNA
New DNA copy
Cell Nucleus
COPY GENETIC MATERIAL
Living things keep a copy of their genetic instructions, as DNA, inside each of their cells. Before a cell can divide to make two cells, it has to copy its DNA. A whole team of proteins work together to do this job. A few are shown here.
Collagen
Connective Tissue
BUILD BODY STRUCTURES
Collagen is the most plentiful protein in your body. And it’s a big part of what holds everything together. It’s in your heart, blood vessels, eyes, skeleton, and more.
Long collagen proteins weave together to form strong meshes and fibers. In different arrangements, collagen helps give each tissue just the right shape, strength, and stretch.
Collagen protein helps to give all animals their structure — even insects and sponges.
Red blood cells
A series of proteins send the message that a wound needs to be covered. The message activates fibrin proteins.
When you get a cut, proteins work together to stop the bleeding. First, signaling proteins send out a message that tissue is damaged. Then fibrin proteins and platelets come together to make a clot.
Platelets
Any animal with blood needs a way to stop bleeding. Some use different proteins than people, but the idea is the same. A signal from the wound brings in proteins to seal it.
Fibrin proteins
Blood Vessel
STOP BLEEDING
Oxygen
Red Blood Cell
CARRY OXYGEN
Hemoglobin protein
Red blood cells are packed full of a protein called hemoglobin. This protein picks up oxygen in the lungs and delivers it to all the body’s tissues.
Hemoglobin proteins have iron-containing heme molecules inside. The heme makes it possible for the protein to carry oxygen. It also gives this protein — and blood — its red color.
Most animals with backbones use hemoglobin to carry oxygen. But even animals with blood that looks very different from ours use a similar protein to do the same job.
Carbohydrate ("starch")
Sugar
Amylase enzyme
Ways Proteins Make You
Build body structures
Digest food
Move ions
Build hair
& nails
Help you see,
taste & feel
Build pigments
Transmit messages in
the brain
Build & move
muscles
Proteins build bodies and make them function.
Choose a process to learn more about how proteins make it happen:
Move nutrients
Stop bleeding
Copy genetic material
Carry oxygen
Signal
Outside cell
Inside cell
Channel proteins
Keratin proteins
Keratin fibers
Glucose transporter
Ions
Piezo protein
DNA Polymerase
Actin proteins
Myosin proteins
Collagen protein
Hemoglobin
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