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Proteins

Proteins

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Description:

This lesson will describe the levels of protein structure as well as define the role of proteins in your body

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Tutorial

What's Covered

Welcome to the lesson on proteins. In today’s lesson, you will be reviewing:

  1. An Overview of Proteins
  2. The Role of Proteins
  3. Amino Acids
  4. The Structure & Function of Proteins

1. An Overview of Proteins

So first of all, proteins are organic compounds. And if you'll remember back, organic compounds are compounds that contain the element carbon. Common organic compounds include proteins, lipids, nucleic acids, and carbohydrates.

Term to Know

Proteins
Organic molecules composed of amino acids.


2. The Role of Proteins

Proteins are made up of something called amino acids; amino acids are the building blocks of proteins. There's many different types of proteins, so they have many different roles.

Example Some examples of ways that proteins are used in your body are as enzymes. They're used for structure, for transport, for movement, for regulation of cell activity and they're used as your hormones. They're also used as receptors to bind hormones to target cells and they're used in defense in your lymphatic system.

So proteins have many, many different roles in your body and they're a very important molecule in your body.


3. Amino Acids

Amino acids are the building blocks of proteins and combine together to form proteins.

Term to Know

Amino Acids

The building blocks of proteins. Amino acids compose proteins.

The diagram below shows the structure of an amino acid.

Screen Shot 2015-11-24 at 1.47.21 PM.png

So in the center, you have a carbon molecule that's going to be covalently bonded to a hydrogen as well as to a carboxyl group. It is also bonded to an R group. So these are all the different components that make up an amino acid.

The R group is going to be distinct to each of the different 20 amino acids that there are. In each of those 20 amino acids, the rest of the structure will be the same, but the R group will be different. One amino acid is going to have a different R group than a different type of amino acid. Each amino acid has its own R group.

So amino acids will make up proteins. The order of amino acids and the number of amino acids is going to compose different types of proteins. So there are many, many different types of proteins, depending on the structure of amino acids.


4. The Structure & Function of Proteins

The structure of a protein has basically four different levels. As you go through the four levels, see the diagram below.

Screen Shot 2015-11-24 at 1.47.40 PM.png

  • Primary Structure:

The primary structure of a protein includes a linear chain of amino acids.

Term to Know

Primary Structure of Proteins

The most simple structure of proteins composed of a chain of amino acids.

Remember, there are 20 different types of amino acids total. So you have a chain here of four amino acids. When you have amino acids together in a chain, you call that a polypeptide chain; the prefix poly means many. So you have many of these amino acids linked together in a chain and they're held together by something called a peptide bonds.

Term to Know

Peptide Bond

A type of bond that joins amino acids together.

These are all different types of amino acids held together by peptide bonds and when you have many amino acids held together by peptide bonds which are refered to as a polypeptide chain. So this is the primary structure of a protein, a polypeptide chain.

  • Secondary Structure:

The secondary structure protein is that polypeptide chain that's then twisted or folded. When the primary structure twists and folds, it produces the secondary structure of a protein.

Term to Know

Secondary Structure of Proteins

The second level of organization of proteins where amino acid chains twist and fold.

  • Tertiary Structure:

The tertiary structure of a protein is made when that secondary structure will start to twist and fold even more, producing a 3D shape. This 3D shape is going to determine how the protein is going to function.

Term to Know

Tertiary Structure of Proteins

The third level of organization of proteins where amino acids continue to twist and fold forming a 3-D shape.

  • Quaternary Structure:

The quaternary structure is formed when you have two or more chains that are held together. After the polypeptide chain has been twisted and folded, and twisted folded more, it is going to combine with other chains. Those other chains are all going to be bonded together.

Term to Know

Quaternary Structure of Proteins

The most complex level of protein structure where the tertiary structure of several amino acid chains are bonded together.


Summary

In this lesson, you learned that proteins are organic compounds found in your body that are built by amino acids and that they have various roles in your body. You also learned about the four different levels of protein structure.


Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Proteins

    ​Organic molecules composed of amino acids.

  • Amino Acids

    ​The building blocks of proteins. Amino acids compose proteins.

  • Peptide Bond

    ​A type of bond that joins amino acids together.

  • ​Polypeptide Chain

    ​A chain formed when three or more amino acids join together.

  • Primary Structure of Proteins

    The most simple structure of proteins composed of a chain of amino acids.

  • ​​Secondary Structure of Proteins

    The second level of organization of proteins where amino acid chains twist and fold.

  • ​Tertiary Structure of Proteins

    ​The third level of organization of proteins where amino acids continue to twist and fold forming a 3-D shape.

  • ​Quaternary Structure of Proteins

    ​The most complex level of protein structure where the tertiary structure of several amino acid chains are bonded together.