Biomolecules

DNA mainly consist of a nitrogeneous base, phosphate group and a pentose sugar.

So, hydrolysis of DNA produces a pentose sugar.

Hence in sucrose glycosidic linkage between $\mathrm{C}_{1}$ of $\alpha$-glucose and $C_{2}$ of $\beta$-D-fructose is found Maltose $\Rightarrow$ Glycosidic linkage between $\mathrm{C}_{1}$ and $\mathrm{C}_{4}$ Lactose $\Rightarrow$ Glycosidic linkage between $\mathrm{C}_{1}$ and $\mathrm{C}_{4}$ Amylose $\Rightarrow$ Glycosidic linkage between $\mathrm{C}_{1}$ and $\mathrm{C}_{4}$

Animal starch is the other name of glycogen because its structure is similar to amylopectin.

Let's analyze the given statements: Assertion A: "Amylose is insoluble in water." This statement is incorrect.

Amylose is actually soluble in water, although its solubility is lower compared to other carbohydrates like amylopectin.

Reason R: "Amylose is a long linear molecule with more than 200 glucose units." This statement is correct, as amylose is indeed a linear polysaccharide made up of glucose units.

Given this information, the correct option is: Option D: $\mathbf{A}$ is not correct but $\mathbf{R}$ is correct.

Seliwanoff 's test is a differentiating test for Ketose and aldose.

This test relies on the principle that the keto hexose are more rapidly dehydrated to form 5-hydroxy methyl furfural when heated in acidic medium which on condensation with resorcinol, Cherry red or brown red coloured complex is formed rapidly indicating a positive test.

Arginine is an amino acid that has a basic side chain containing a guanidino group.

The other three options are true for arginine: (A) It has a fairly high melting point due to the presence of strong ionic interactions between the positively charged guanidino group and the negatively charged carboxylate group in the solid state.

(B) It is associated with more than one pKa values because it contains multiple ionizable groups, including the amino group, the carboxylate group, and the guanidino group.

These groups can dissociate in a stepwise manner, leading to multiple pKa values.

(D) It is a crystalline solid due to the presence of strong ionic interactions between the positively charged guanidino group and the negatively charged carboxylate group, which leads to the formation of a well-ordered crystal lattice.

However, option (C) is not true because arginine is not soluble in benzene.

This is because benzene is a nonpolar solvent, and arginine is a polar and charged molecule.

Therefore, arginine is more soluble in polar solvents such as water and less soluble in nonpolar solvents such as benzene.

Among the given options, arginine, histidine, and lysine are all basic amino acids because they contain amino (-NH2) and imino (-NH=) functional groups that can accept a proton (H+) to become positively charged.

Asparagine, on the other hand, contains an amide (-CONH2) functional group instead of an imino group.

This functional group is not basic because it does not have a proton that can be easily removed.

Therefore, the answer is: asparagine.

The stabilization of secondary (2°) and tertiary (3°) structures of proteins mainly involves interactions such as disulfide bridges (S-S linkages), van der Waals forces, hydrogen bonding, and hydrophobic interactions.

Option A: O-O linkage is not usually involved in the stabilization of protein structures.

Oxygen-oxygen single bonds are generally unstable and rarely observed in nature.

Option B: S-S linkage (disulfide bridges) between cysteine residues in a protein can help stabilize the protein's structure, particularly its tertiary structure.

Option C: Van der Waals forces can contribute to the stabilization of protein structures, particularly in the interior of the protein where they can promote hydrophobic interactions.

Option D: Hydrogen bonding can play a critical role in the formation and stabilization of secondary structures such as alpha-helices and beta-sheets.

Therefore, the correct answer is Option A (-O-O- linkage).

Isoleucine is an $\alpha$-amino acid that is used in the biosynthesis of proteins.

It contains an $\alpha$ amino group, an $\alpha$-carboxylic acid group, and a hydrocarbon side chain with a branch.

It is classified as a non-polar, uncharged, branchedchain, aliphatic amino acid.

Lysine is an $\alpha$-amino acid that is a precursor to many proteins.

It contains an $\alpha$-amino group, an alpha-carboxylic acid group, and a side chain lysyl, classifying it as a basic, charged, aliphatic amino acid.

It is encoded by the codons AAA and AAG.

Glutamic acid is an amino acid used to form proteins.

Cysteine and methionine are sulphur containing amino acids.

Amino acids get linked to one another by peptide bond formation and form a polypeptide chain of proteins.

Hence cysteine and methionine are found in several proteins. (a) isoleucine (b) cysteine (c) lysine (d) methionine (e) glutamic acid

Phosphodiester linkage