Proteins - Retrieval Questions 2

Why are secondary structures stable?

Because they have hundreds of hydrogen bonds

What is the secondary structure of a protein?

It is the curling or folding of the polypeptide chain into alpha helixs and beta pleated sheets due to the formation of hydrogen bonds.

After secondary structure, what do the alpha helixs and beta pleated sheets do?

They form tertiary structures by twisting and turning.
This forms a protein with a unique 3-D structure.

How is the tertiary structure held in place?
(Hint : there is three ways)

It is held in place by the:
- ...hydrogen bonds that form between the polar R groups.
- ...ionic bonds between the positively and negatively charged R-groups
- ...disulphide links between the sulphur atoms in the R-groups.

What is the tertiary groups decided by?

The hydrophillic and hydrophobic R-groups.

Where are the amino acids with hydrophobic R-groups found?

In the centre of the proteins.

Where are the amino acids with hydrophillic R-groups found?

On the outside of the proteins.

What is the overall tertiary structure a result of?

The primary structure determines the tertiary structure, and sp does the R-groups and interactions.

What is the tertiary structure of a proteins?

It is the overall specific 3-D shape of a protein. This is determined by interactions between R groups and properties of R groups.

What is the quaternary structure?

The final structure of a protein.

What are the polypeptide chains in the quaternary structure held together by?

Hydrogen bonds
Ionic bonds
Disulphide links

In the quaternary structure, what else can be associated with the polypeptide chain?

Non-protein groups (prosthetic groups).

What forms once the non-protein groups associate with the polypeptide chain?

Conjugated proteins.

What causes the formation of the proteins to have a unique quaternary structure?

The bonding of different chains and non-protein group.

Define the quaternary structure.

It is the specific 3-D shape of a protein that is determined by the multiple polypeptide chains and/or prosthetic groups bonded together.

What can break the bonds that maintain the structure of proteins?

Changes in temperature.
Changes in pH.

Define denatured.

It is when the protein changes shape and prevents it from being able to carry out its function.

What are the two types of quaternary structures?

Fibrous
Globular

What are the properties of globular proteins?

They are roughly spherical in shape, with hydrophobic R groups are on the inside and hydrophilic R groups on the outside.
They are soluble in water.
They have specific shapes which allows them to carry out specific functions.

Roles of globular proteins.

Transport proteins
Hormones
Enzymes