honors bio

bio

What are some of the functions of proteins?

Proteins can be used for transportation, Enzymes (speed up reactions), structure, immune system protection, store nutrients and other things,communicating, regulate homeostasis

What determines a protein’s shape and function?

The sequence of amino acids

What are the components of an amino acid?

Central carbon to which four functional groups are attached: hydrogen, amino group, carboxyl group, and variable R group

What makes each amino acid unique?

The R group

What are some of the properties of R groups?

Some are hydrophobic, some may be charged, polar or nonpolar, some may be acidic or basic

How do these properties drive the formation of the three-dimensional structure of a protein?

If an R group is hydrophilic, it will force itself to be in contact with water on the outside of the 3-D structure, Conversely, hydrophobic amino acids stay in the interior of the protein

What is the name of the bond that forms between amino acids? Are these bonds covalent or ionic?

Bonds between the amino acids are covalent peptide bonds

What is Primary Structure

The sequence of amino acids

What is Secondary structure

Formation of simple motifs ( alpha helix, beta sheets) that are the result of amino acid interactions

What is tertiary structure

Three dimensional structure of the polypeptide (includes primary and secondary structures)

What is Quaternary structure

Two or more polypeptide chains in association with each other, each polypeptide chain has its own primary structure, secondary structure, and tertiary structure

“No matter what the function of a protein is, the ability to carry out this function depends on…”

“…the three dimensional structure of the protein.”

What type of bond holds secondary structures together?

Hydrogen Bonds

Interactions of what sort define the tertiary structure?

The tertiary structure is a collection of interactions between secondary and primary structure segments of the chain.

R group properties drive the structure of a three-dimensional protein’s shape. Hydrophilic R groups will bend that section of the polypeptide toward water or hydrophobic groups will twist that section of the chain toward the interior of the protein, for example. Interactions between R groups drive the formation of the mature polypeptide chain.

How can R groups form bonds with others that are far away in the polypeptide chain?

Loops and turns in the polypeptide chain

The primary and secondary structures determine the structure of the protein. What does the tertiary structure determine?

By the time the protein has a tertiary structure, it has the proper shape for its proper function

What is denaturation?

Denaturation is changing the nature of the protein. This involves a change in the shape of a protein and therefore, a change in the function of the protein.

However, many,many,many proteins do not perform their normal functions without a slight change in shape (conformation). If the change in shape is severe, the protein becomes denatured and will not function.

What determines the activity of a multisubunit protein with a quaternary structure?

Each subunit (single polypeptide chain) has a specific shape and orientation that comes together with the other subunits to make the functional protein.

Do all proteins have a primary structure? Secondary? Tertiary? Quaternary?

Yes; no but most do; no but many do; no

What is the role of chaperone proteins? Why are they needed for some types of protein folding?

Chaperone proteins direct folding or protect proteins as they are folding