Proteins

A polypeptide is

a chain of amino acids.

The building blocks of proteins are

amino acids.

Amino acids have an ______ at one end and a _____ at the other end.

amino group carboxyl group

In secondary structure, a polypeptide chain forms

an alpha helix or a beta-pleated sheet.

Four elements always found in proteins are

carbon, hydrogen, oxygen, and nitrogen.

Enzymes are

catalysts in living systems.

Peptide bonds are

covalent bonds between amino acids.

Four things that cause a protein to denature are

heat, radiation, pH changes, and certain chemicals.

Protein function is determined by

its distinct conformation created by its primary, secondary, and tertiary structures.

When a protein denatures, it

loses its tertiary or secondary structure.

The four levels of protein structure are

primary, secondary, tertiary, and quaternary.

Hydrogen bonding determines

secondary structure.

The quaternary structure of a protein forms when

several polypeptide chains connect to form a very large protein.

One element sometimes found in proteins is

sulfur.

The folding of secondary structure is called

tertiary structure.

The primary structure of a protein is

the amino acid sequence of the polypeptide chain.

The twenty amino acids differ in

their side chains or R groups.

Three important functions of proteins are

to serve as structurel materials, energy sources, and chemical messengers. Proteins also function as receptors, antibodies, and enzymes.