Proteins AP Biology

Summary

Proteins are complex organic macromolecules built from sequences of 20 different amino acids, each with a unique R group. Amino acids join via dehydration synthesis, forming polypeptide chains. These chains fold into specific 3D shapes through interactions among R groups, resulting in secondary and tertiary structures. Some proteins, like hemoglobin, achieve quaternary structure by combining multiple polypeptides. Protein shape dictates function, allowing them to serve various roles in cells, including structural, communicative, metabolic, and transport functions.

Takeaways

• 🧬 Proteins are organic macromolecules made from sequences of amino acids.
• 🌿 Amino acids in proteins contain carbon, hydrogen, oxygen, and nitrogen.
• 🔬 There are 20 different amino acids, each with a unique R group.
• 🔗 Amino acids have a central carbon atom bonded to a hydrogen atom, a carboxyl group, and an amino group.
• 💧 Dehydration synthesis forms covalent bonds between amino acids, resulting in a polypeptide chain.
• 🧩 The primary structure of a protein is its specific sequence of amino acids in a polypeptide chain.
• 🌀 Secondary protein structure involves alpha helices and beta sheets formed by hydrogen bonding.
• 🔄 Tertiary structure arises from interactions among R groups, leading to the protein's unique 3D shape.
• 🔄 Quaternary structure occurs when two or more polypeptides join to form a functional protein.
• ⚛️ Proteins perform diverse functions such as cell structure, communication, metabolism, defense, and transport.

Q & A

What are proteins made of?

Proteins are organic macromolecules built from a sequence of amino acids, which are covalently bonded together.

What elements do amino acids and proteins contain?

Amino acids and proteins contain the elements carbon, hydrogen, oxygen, and nitrogen.

How many different amino acids are there and what makes each unique?

There are 20 different amino acids, each made unique by their variable region of atoms called an R group.

What is the general structure of an amino acid?

An amino acid contains a central carbon atom bonded to a hydrogen atom, a carboxyl group, and an amino group. Additionally, each amino acid has a variable region called an R group.

What reaction joins amino acid monomers, and what does it produce?

The reaction that joins amino acid monomers is called dehydration synthesis, which involves the loss of water and the formation of a covalent bond, producing a polypeptide.

What is the primary structure of a protein?

The primary structure of a protein is a linear chain of amino acids covalently bonded together, forming a polypeptide.

What are the secondary structures in proteins, and how are they formed?

Secondary structures in proteins include alpha helices and beta sheets, which are formed by hydrogen bonding between the backbone of the polypeptide.

What determines the tertiary structure of a protein?

The tertiary structure of a protein is determined by interactions among the R groups of amino acids, including polar, nonpolar, and ionic interactions.

What is quaternary protein structure?

Quaternary protein structure occurs when two or more polypeptides join together to form a functional protein.

Why is the shape of a protein important?

The shape of a protein determines its biological function. Proteins must have specific 3D shapes to perform various functions such as cell structure, communication, metabolism, defense, and transport.

What is an example of a protein with quaternary structure?

Hemoglobin, a protein found in red blood cells that functions in oxygen transport, is an example of a protein with quaternary structure, made from four polypeptides.