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Basics of Biology

Enzymes—and Proteins—at Work

What are proteins, and how do they work?

Proteins do, in a word, everything. Proteins allow life to exist as we know it. They are the enzymes that are required for all metabolic reactions. They are also important to structures like muscles and act as both transporters and signal receptors. The following chart lists the types of functions of proteins:

 

 

 

 

 

 

 

 

Type of protein

Examples of functions

 

 

 

 

 

 

 

 

Defensive

Antibodies that respond to invasion

 

 

 

 

 

 

 

 

Enzymatic

Increase the rate of reactions, build and break down molecules

 

 

 

 

 

 

 

 

Hormonal

Insulin and glucagon, which control blood sugar

 

 

 

 

 

 

 

 

Receptor

Cell surface molecules that cause cells to respond to signals

 

 

 

 

 

 

 

 

Storage

Store amino acids for use in metabolic processes

 

 

 

 

 

 

 

 

Structural

Major components of muscles, skin, hair, horns, spider webs

 

 

 

 

 

 

 

 

Transport

Hemoglobin carries oxygen from lungs to cells



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