Question

Define and describe protein 1 degree, 2 degree, 3 degree, 4 degree structure c know amino acid sidechain know forces that determine protein 30 structure Define protein and domain families
1-3 thank you

Answer 1

1) Proteins are biopolymers containing a large number of amino acids joined to each other by peptide linkages having three dimensional structures. The structure of proteins is a complex one which is divided into 4 parts. They are primary, secondary, teritiary and quaternary structures.

The simplest level of protein structure, primary structure, it is composed of various amino acids held together by peptide bonds. This structure is responsible for the function of a protein.

The next level of protein structure, secondary structure, refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. The most common types of secondary structures are the α helix and the β pleated sheet. Both structures are held in shape by hydrogen bonds, which form between the carbonyl O of one amino acid and the amino H of another. In an α helix, C=O group of one amino acid is hydrogen bonded to the N-H group of another amino acid in the chain. In a β pleated sheet, two or more segments of a polypeptide chain line up next to each other, forming a sheet-like structure held together by hydrogen bonds.

The overall three-dimensional structure of a polypeptide is called its tertiary structure. It coils and folds in such a way that the hydrophobic side chains are held in the interior and the hydrophilic groups are held outside. This arrangement gives stability to the molecule.

Many proteins are made up of a single polypeptide chain and have only three levels of structure. However, some proteins are made up of multiple polypeptide chains, also known as subunits. The spatial arrangement of these subunits with respect to each other is known as quaternary structure.

2) Protein 3D structure is tertiary structure. The tertiary structure is maintained by hydrogen bonds, disulfide bonds, ionic bonds and hydrophobic interactions.

3) A protein family is a group of proteins that share a common evolutionary origin, reflected by their related functions and similarities in sequence or structure. Domains are distinct functional and structural units in a protein. Usually they are responsible for a particular function or interaction, contributing to the overall role of a protein.