Protein Structure and Denaturation

Answer:- (C) hydrogen bonds

In $\alpha -$helix structure, polypeptide chains are folded in a both way (heft hand and write hand).

Cheese is a denatured protein. When producing (hard or semi-hard) cheese, the cheese yield can be increased by subjecting part of the cheese milk to a high temperature heat treatment. Thermal denaturation of whey proteins changes the protein structure so that part of the whey remains in the curd during the cheese-making process. 

Denaturation of proteins can be carried out by heat, mineral acids or bases. Denaturation is a process in which proteins lose their quaternary, tertiary and secondary structure which is present in their native state by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent, radiation or heat. If proteins in a living cell are denatured, it results in disruption of cell activity and possibly cell death. Denatured proteins can exhibit a wide range of characteristics from loss of solubility to communal aggregation.

Option (C) is correct.
Enzymes are globular proteins, and catalyze metabolic reactions in living organisms.
They have a specific tertiary structure with an active site complementary to the substrate. They can speed up a reaction but do not get used up. Their activity can be affected by temperature and $pH$.

The primary structure of a protein is defined by the linear sequence of amino acids linked by peptide bonds. Secondary, tertiary, and quaternary structures refer to the folding and spatial arrangement of this chain.

Globular Proteins have three dimensional folded structure. These are cross linked proteins, soluble in water.
Globular Proteins are present in blood, eggs and milk.

Globular Proteins have three dimensional folded structure.
These are cross linked protein.
They are Soluble in water.
Fibrous Proteins are linear condensation polymers.
They are Insoluble in water.
These are held together by intermolecular hydrogen bond.

The secondary structure of a protein refers to either of $\alpha$-helical back bone or $\beta$-sheet.

Myoglobin or haemoglobin is a globular protein.

 Globular proteins are present in egg albumin, haemoglobin, myoglobin, insulin, serum globulins in blood, and many enzymes.

Proteins are linear polymers formed by linking the -carboxyl group of one amino acid to the -amino group of another amino acid with a peptide bond.

Proline is the only proteinogenic amino acid whose side-group links to the -amino group and, thus, is also the only proteinogenic amino acid containing a secondary amine at this position.

Proteins may have one or more polypeptide chains. Each polypeptide in a protein has amino acids linked with each other in a specific sequence and it is this sequence of amino acids that is said to be the primary structure of that protein.

Primary structure refers specifically to the unique sequence of amino acids in a polypeptide chain. Other options describe higher-level folding or structural organization.

The tertiary structure of proteins is stabilized by various interactions between the side chains of amino acids. These include hydrogen bonds, Van der Waals forces, ionic bonds, and covalent disulphide linkages. Since multiple types of interactions are responsible, all the listed options play a role.

Given statement is false.

Myoglobin is a simple protein consisting of a single polypeptide. Since the quaternary structure is composed of an assembly of subunits of polypeptides, myoglobin does not have a quaternary structure. Due to the lack of multiple subunits, it has the highest level of structure as tertiary. Hemoglobin, on the other hand,  is composed of multiple polypeptide subunits, each capable of binding and transporting one molecule of oxygen in the blood, thus giving it a quaternary structure.

While primary structure is held together by covalent peptide bonds, secondary structures (like alpha-helices and beta-pleated sheets) are formed and stabilized by hydrogen bonding between the backbone atoms.

The building block of proteins are $ \displaystyle \alpha-$amino acids.
On hydrolysis, proteins gives  $ \displaystyle \alpha-$amino acids.
 $ \displaystyle \alpha-$amino acids have structure  $ \displaystyle H _2N- \underset {  \displaystyle   { \underset {  \displaystyle  \text { R } }{ | } } }{CH }-COOH$
Proteins $ \displaystyle \xrightarrow {H _2O}n H _2N- \underset {  \displaystyle   { \underset {  \displaystyle  \text { R } }{ | } } }{CH }-COOH$
Proteins are polypeptides and contain peptide linkage ($ \displaystyle - \underset {  \displaystyle   { \underset {  \displaystyle  \text { O } }{ || } } }{C }-NH-$ linkage)