Question

what are proteins? how are they classified? discuss briefly about their primary secondary and tertiary structures​

Answer 1

Answer:

Primary structure is the amino acid sequence. Secondary structure is local interactions between stretches of a polypeptide chain and includes α-helix and β-pleated sheet structures. Tertiary structure is the overall the three-dimension folding driven largely by interactions between R groups.

Explanation:

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Answer 2

Answer:

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Explanation:

Definition of protein

Proteins are macromolecular polypeptides. They are the large biomolecules and macromolecules that are comprised of one or more long chains of amino acid residues.

Classifications of Proteins;

Proteins are classified based on their

• Solubility and composition

• Function

• Shape & size

1. SOLUBILITY AND COMPOSITION

According to this classification, Proteins are divided into 3 main groups

• Simple
• Conjugated
• Derived

Simple;

This is grouped into these;

• Albumins
• Globulins
• Prolamins
• Glutelin
• Histones
• Protamine
• Albuminoid

Conjugated;

They are grouped into these;

• Nucleoproteins
• Mucoproteins
• Chromoproteins
• Lipoproteins
• Metalloproteins
• phosphoproteins

Derived;

Consists of two types;

• Primary-derived proteins
• Secondary-derived proteins

2. FUNCTION

These are sub-divided into 10. These are the;

• Catalytic proteins - enzymes

• Regulatory proteins - Hormones
• Protective proteins - Antibodies
• Storage Proteins
• Transport proteins
• Toxic proteins
• Structural proteins
• Contractile proteins
• Secretary proteins and the
• Exotic proteins

3. Size And Shape

These are sub-divided into 2. These are the;

• Globular and
• Fibrous

STRUCTURES OF A PROTEIN

Primary-

• The Primary structure of proteins is the exact ordering of amino acids forming their chains.

• The exact sequence of the proteins is very important as it determines the final fold and therefore the function of the protein.

• the primary structure of a protein is the linear sequence of amino acids. Together, this linear sequence is referred to as a polypeptide chain. The amino acids in the primary structure are held together by covalent bonds, which are made during the process of protein synthesis.

Secondary-

• The proteins do not exist in just simple chains of polypeptides.
• These polypeptide chains usually fold due to the interaction between the amine and carboxyl group of the peptide link.
• The structure refers to the shape in which a long polypeptide chain can exist.
• They are found to exist in two different types of structures α – helix and B – pleated sheet structures.
• This structure arises due to the regular folding of the backbone of the polypeptide chain due to hydrogen bonding between -CO group and -NH groups of the peptide bond.
• However, segments of the protein chain may acquire their own local fold, which is much simpler and usually takes the shape of a spiral an extended shape or a loop. These local folds are termed secondary elements and form the proteins secondary structure.

Tertiary-

• This structure arises from further folding of the secondary structure of the protein.

• H-bonds, electrostatic forces, linkages, and Vander Waals forces stabilize this structure.

• The tertiary structure of proteins represents overall folding of the polypeptide chains, further folding of the secondary structure.

• It gives rise to two major molecular shapes called fibrous and globular.

• The main forces which stabilize the secondary and tertiary structures of proteins are hydrogen bonds, van der Waals and electrostatic forces of attraction.