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What are proteins? Surprise – they are chemicals!

They’re made of smaller chemical units called amino acids.

Here we see 2 amino acids joining together to make a mini-protein.

Some atoms are left over: 1 O and 2 H.

They float off as an H2O molecules (water – which is another chemical)

Amino acid and peptide bond

Imagine getting many amino acids.

Then they bond to each other, making a chain.

Then it folds up into a 3D shape – that’s a protein.


Where do our body’s proteins come from?

We eat food with proteins – vegetarian or meat – and break them down into individual amino acids.

Then our DNA instructs our cells to attach them in a new sequence.

Vegan Protein nuts vegetables

What is their job?

Some float in the lipid bilayer (cell membrane)

They control which molecules enter or leave the cell.

Creative Biomart Lipidsome-Based-Membrane-Protein-Production

Some are hormones (chemical messengers)

They’re released in one part of the body and travel to another part.

Pituitary gland Adrenal gland Kidney Endocrine hormone

from Mar Vista Animal Medical Center, marvistavet.com

Cell organelles are made of proteins and lipids


Hair and nails are made of protein

Hair and nails

Bone isn’t mysterious – it is a matrix of protein fibers and minerals

Antibodies are a special type of protein; they have a shape which attaches to bacteria or viruses.

Antibody Immune Response by Nucleus Medical Media

Chemical reactions in our cells, by themselves, are too slow.
So some proteins are specially shaped to speed of those reactions.
Such proteins are called enzymes.

Salivary amylase enzyme mouth GIF

from dynamicscience.com.au

Skin pigments are from colorful proteins.

Eye pigments are from colorful proteins.

Eye color pigments

Learning Standards

HS-LS1-6. Construct an explanation based on evidence that organic molecules are primarily composed of six elements, where carbon, hydrogen, and oxygen atoms may combine with nitrogen, sulfur, and phosphorus to form monomers that can further combine to form large carbon-based macromolecules.
Clarification Statements:
• Monomers include amino acids, mono- and disaccharides, nucleotides, and fatty acids.
• Organic macromolecules include proteins, carbohydrates (polysaccharides), nucleic acids, and lipids.

Disciplinary Core Idea Progression Matrix: PS1.A Structure of matter

That matter is composed of atoms and molecules can be used to explain the properties of substances, diversity of materials, how mixtures will interact, states of matter, phase changes, and conservation of matter.

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