Biomolecules

Structure (1) given is of sucrose which is non reducing.

For non reducing sugar compound should have acetal linkage not hemi acetal linkage.

Gly ala val

Gly val ala

Val gly ala

Val ala gly

Ala val gly

Ala gly val

Total tri peptides $=6$

DNA and RNA show chirality because they contain a chiral sugar in their structure.

In DNA, the sugar present is chiral 2-deoxy-Ribose.

In RNA, the sugar present is chiral Ribose.

$ \begin{aligned} & {[\alpha]_{D \text {-sucrose }}=+66.5^{\circ}, \quad[\alpha]_{D \text {-Glucose }}=+52.5^{\circ}} \\ & {[\alpha]_{D \text {-Fructose }}=-92.4^{\circ}} \end{aligned} $

⇒ Sucrose is dextrorotatory and hydrolysed product is laevorotatory.

A. Activation energy for enzyme catalysed hydrolysis of sucrose is lower than that of acid catalysed hydrolysis.

• Enzymes are biological catalysts that increase the rate of reactions by lowering their activation energy.

• Acid catalysis also provides an alternative reaction pathway, but enzymes are typically much more efficient at lowering activation energy under physiological conditions.

• For the hydrolysis of sucrose, the enzyme sucrase (invertase) significantly reduces the activation energy compared to acid-catalyzed hydrolysis, making the reaction much faster.

• Therefore, statement A is correct.

B. During denaturation, secondary and tertiary structures of a protein are destroyed but primary structure remains intact.

• Denaturation is the process by which proteins lose their native three-dimensional structure (secondary, tertiary, and if present, quaternary structures) due to disruptions of weak interactions (like hydrogen bonds, hydrophobic interactions, ionic bonds).

• The primary structure, which is the sequence of amino acids linked by strong covalent peptide bonds, is generally not broken during denaturation. Breaking peptide bonds would require harsh conditions like strong acid/base hydrolysis or specific proteases.

• Therefore, statement B is correct.

C. Nucleotides are joined together by glycosidic linkage between C1 and C4 carbons of the pentose sugar.

• Nucleotides are linked together in nucleic acids (DNA and RNA) by phosphodiester bonds.

• A phosphodiester bond forms between the phosphate group attached to the 5' carbon of one nucleotide and the hydroxyl group on the 3' carbon of the pentose sugar of the next nucleotide.

• A glycosidic linkage (specifically, an N-glycosidic bond) connects the nitrogenous base to the C1 carbon of the pentose sugar within a single nucleotide. It does not link nucleotides together, nor does it involve C1 and C4 carbons between different pentose sugars.

• Therefore, statement C is incorrect.

D. Quaternary structure of proteins represents overall folding of the polypeptide chain.

• The tertiary structure describes the overall three-dimensional folding of a single polypeptide chain.

• The quaternary structure refers to the arrangement of multiple polypeptide subunits (each having its own tertiary structure) to form a functional protein complex. It describes how these individual chains associate with each other.

• Therefore, the statement describes tertiary structure, not quaternary structure.

• Therefore, statement D is incorrect.

Conclusion:

Statements A and B are correct. Statements C and D are incorrect.

The correct option should include only A and B.

The final answer is $\boxed{\text{A and B Only}}$

Arginine and Tryptophan are essential amino acids.

When oligopeptides undergo hydrolysis, they yield a small number of α-amino acids. In contrast, proteins do not produce β-amino acids upon hydrolysis. Thus, Statement I is incorrect.

Furthermore, natural proteins, when subjected to denaturation by acids, do not convert fibrous proteins from a water-soluble to a water-insoluble form, as fibrous proteins are inherently not water-soluble. Therefore, Statement II is also incorrect.

In conclusion, both Statement I and Statement II are incorrect.

In Statement I, the reaction shown is incorrect. During the hydrolysis of sucrose, D-(+)-glucose and D-(-)-fructose are produced. However, the statement incorrectly specifies D-(+)-fructose, making Statement I inaccurate.

Statement II is accurate. When sucrose undergoes hydrolysis, it results in the formation of invert sugar, a mixture of glucose and fructose. This change involves the inversion of optical rotation, which is where the term "invert sugar" comes from.

Fat-soluble vitamins are A, D, E and K. From the list:

A: Vitamin B₁ – water-soluble

B: Vitamin C – water-soluble

C: Vitamin E – fat-soluble

D: Vitamin B₁₂ – water-soluble

E: Vitamin K – fat-soluble

So the fat-soluble ones are C (E) and E (K), which is Option C.

To determine the number of tetrapeptide sequences possible using the amino acids glycine (Gly), alanine (Ala), valine (Val), and leucine (Leu), we consider the concept of permutations. Since each tetrapeptide sequence consists of four different amino acids, we need to calculate the number of ways to arrange these four different elements.

The formula for the number of permutations of a set of $ n $ distinct elements is given by $ n! $ (n factorial), where $ n! = n \times (n-1) \times (n-2) \times \cdots \times 1 $.

For our case:

$ n = 4 $

Hence, the number of possible sequences (or permutations) is:

$ 4! = 4 \times 3 \times 2 \times 1 = 24 $

Thus, there are 24 different tetrapeptide sequences possible using each of the four amino acids exactly once.

To clarify the statements regarding amino acids:

Chirality in Amino Acids: Most naturally occurring amino acids contain at least one chiral center, but there are exceptions. For example, Isoleucine has two chiral centers, and Glycine is an exception as it is optically inactive due to lacking a chiral center.

Cysteine and Dimerization: The amino acid Cysteine can easily undergo dimerization. This is due to its free sulfhydryl (SH) group, which can form disulfide bonds, leading to the formation of a dimer.

Carboxyl Groups in Amino Acids: Glutamic acid is not the only amino acid with a carboxyl group in its side chain. Aspartic acid also contains a carboxyl group in its side chain.

Optical Activity: While many naturally occurring amino acids are indeed optically active, Glycine is an exception as it does not possess a chiral center and is hence optically inactive.

In summary:

Not all naturally occurring amino acids are optically active (e.g., Glycine).

Not all naturally occurring amino acids contain only one chiral center (e.g., Isoleucine has two).

Both Glutamic acid and Aspartic acid contain side chain carboxyl groups.

Cysteine can dimerize due to its SH group.

The nine essential amino acids that must be obtained from the diet are:

Histidine

Isoleucine

Leucine

Lysine

Methionine

Phenylalanine

Threonine

Tryptophan

Valine

From the provided list:

Valine (A) is essential.

Proline (B) is non-essential.

Lysine (C) is essential.

Threonine (D) is essential.

Tyrosine (E) is non-essential (it is considered conditionally essential, but under normal conditions it is non-essential).

Thus, the essential amino acids among those listed are Valine, Lysine, and Threonine.

So the correct answer is:

$\textbf{Option A: (A), (C) and (D) only}$

A) Amylose - Polysaccharide of glucose units with glycosidic linkage $\alpha-1,4$.

The source is plant.

So, the linkage is $\alpha-c_1-C_4$.

Glucose units in amylose are linked by alpha bonds between the $1^{\text {st }}$ and $4^{\text {th }}$ carbon atoms.

Amylose match with $\alpha-c_1-c_4$, plant

(A) with (IV)

B) Cellulose - The glycosidic linkage in cellulose is $\beta-1,4$. Glucose monomers are joined by linkage between the $c_1$ of the one glucose ling and the $C_4$ of the next ring.

Source is plant

Cellulose match with $\beta-C_1-C_4$, plant.

(B) with (I)

c) Glycogen - Glycogen is a polymer of glucose that is stored in animals as an energy reserve. It is used as carbohydrate storage in animals. It is a polymer of $\alpha$-glucose with $\alpha-1,4$-glycosidic and $\alpha-1,6$-glycosidic links.

$\alpha-1,4$-linkage forms during linear polymer.

$\alpha-1,6$ - linkage forms during the formation of branching.

Glycogen match with $\alpha-C_1-C_4$, animal

(C) with (II)

D) Amylopectin - It is the polymer of glucose units linked by $\alpha-1,4$ and $\alpha-1,6$ glycosidic bonds.

$x-1,4$ - glucose units linked in a linear way.

$\alpha-1,6$ - These bonds branch out from the linear chains of glucose units.

They are stored in large complexes called starch granules in plants.

Amylopectin match with $\alpha-c_1, c_4, \alpha-c_1-c_6$, plant (D) with (III).

Answer: $(A)-($ IV $),(B)-(I),(C)-($ II $),(D)-($ III $)$. Option (3).

(A) Sucrose $\rightarrow \alpha_1-\beta_2$ Glycosidic linkage

(B) Maltose $\rightarrow \alpha$ 1-4 Glycosidic linkage

(C) Lactose $\rightarrow \beta$ 1-4 Glycosidic linkage

(D) Amylopectin $\rightarrow \alpha$ 1-4 and $\alpha$ 1-6 Glycosidic linkage

$\mathrm{A}-\mathrm{III}, \mathrm{~B}-\mathrm{I}, \mathrm{C}-\mathrm{IV}, \mathrm{D}-\mathrm{II}$

(A) Starch $\xrightarrow{\mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}}$ Glucose

(B) $\mathrm{\mathop {Cane\,sugar}\limits_{(Sucrose)} \buildrel {{H^ + }/{H_2}O} \over \longrightarrow \mathop {glu\cos e}\limits_{50\% } \, + \mathop {fructose}\limits_{50\% }}$

(C) $\mathrm{\mathop {Milk\,sugar}\limits_{(Lactose)} \buildrel {{H^ + }/{H_2}O} \over \longrightarrow glu\cos e\, + \,galactose}$

(D) Amylopectin $\xrightarrow{\mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}}$ Glucose

(E) Amylose $\xrightarrow{\mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}}$ Glucose

So, correct options are B, C and E only

Statement I: D-glucose pentaacetate does not react with 2,4-dinitrophenylhydrazine (DNPH). This is because D-glucose pentaacetate is a derivative where all the hydroxyl groups of D-glucose have been acetylated, eliminating the presence of a free aldehyde group. Since DNPH reacts specifically with free aldehyde or ketone groups to form hydrazones, D-glucose pentaacetate does not participate in this reaction.

Statement II: Starch, when heated with concentrated sulfuric acid at 100°C and under a pressure of 2-3 atmospheres, undergoes hydrolysis. This process breaks the glycosidic linkages in starch, resulting in the production of glucose. This statement is accurate as starch is a polysaccharide composed of glucose units and can be broken down into glucose under these conditions.

The correct information based on the statements is:

Statement I is false, as D-glucose pentaacetate does not react with 2,4-dinitrophenylhydrazine due to the absence of a free aldehyde group.

Statement II is true, as the described method effectively converts starch into glucose.

In Ribose carbohydrate present in DNA is $\beta-2-$ Deoxy-D-Ribose whose structure is

which is a reducing $D$-sugar in $\beta$ anomeric form & it is a pentose sugar.

$\alpha$-helix and $\beta$-pleated sheet belongs to secondary structure of protein, which have hydrogen bonds.

In $\mathrm{A}, \mathrm{B}, \mathrm{D}-\mathrm{OH}$ group in right hand side then D-configuration is assigned.

Correct Answer: Ascorbic Acid

Ascorbic acid is commonly known as Vitamin C. It is a water-soluble vitamin essential for various bodily functions, including:

$\textbf{Antioxidant Function:}$ It helps protect cells from damage caused by free radicals.

$\textbf{Collagen Synthesis:}$ It is crucial for the formation of collagen, a protein necessary for skin, cartilage, tendons, ligaments, and blood vessels.

$\textbf{Immune Support:}$ It supports the immune system by enhancing the body's natural defenses.

$\textbf{Iron Absorption:}$ It improves the absorption of non-heme iron from plant-based foods.

Among the given options, only ascorbic acid qualifies as a vitamin.

Let's analyze each statement to identify the incorrect one about glucose.

Option A: Glucose remains in multiple isomeric forms in its aqueous solution. This statement is correct. Glucose exists in equilibrium with various isomeric forms in solution, including its linear form and two cyclic forms (alpha and beta anomers) that result from the formation of a hemiacetal bond within the molecule itself. The interconversion between these forms is known as mutarotation.

Option B: Glucose is soluble in water because of having an aldehyde functional group. This statement is incorrect though it might seem partially true at first glance. While the aldehyde group can participate in hydrogen bonding, the primary reason glucose is highly soluble in water is due to its multiple hydroxyl (-OH) groups that can form hydrogen bonds with water molecules. The ability to form numerous hydrogen bonds makes glucose highly water-soluble, not just the presence of an aldehyde group.

Option C: Glucose is an aldohexose. This statement is correct. Glucose is classified as an aldohexose because it contains an aldehyde group (-CHO) on its first carbon and has a total of six carbon atoms, making it a hexose sugar.

Option D: Glucose is one of the monomer units in sucrose. This statement is correct. Sucrose is a disaccharide composed of two monomers: glucose and fructose. Thus, glucose is indeed one of the monomer units in sucrose.

In summary, the incorrect statement about glucose is Option B: Glucose is soluble in water because of having an aldehyde functional group. The primary reason for its solubility in water is the hydroxyl groups' ability to form extensive hydrogen bonding, not solely the presence of an aldehyde functional group.

Hydroxyapatite : $\left[3\left(\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2\right) \cdot \mathrm{Ca}(\mathrm{OH})_2\right]$

Fluoroapatite : $\left[3\left(\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_2\right) \cdot \mathrm{CaF}_2\right]$

The given structure is of glucose.

Glucose does not give Schiff test due to absence of aldehyde group in ring structure, glucose on reaction with $\mathrm{Br}_2 / \mathrm{H}_2 \mathrm{O}$ give gluconic acid which is mono carboxylic acid.

The correct answer is Option A: (B) and (D).

Let’s analyze each statement:

(A) Enzymes are biocatalysts. - This statement is correct. Enzymes are indeed biocatalysts, meaning they are natural catalytic substances produced by living organisms to speed up chemical reactions in cells without being consumed in the process. They are crucial for a myriad of biological processes.

(B) Enzymes are non-specific and can catalyse different kinds of reactions. - This statement is incorrect. Enzymes are highly specific in nature; they typically catalyze only one kind of reaction or a very limited range of reactions. This specificity is a result of the unique 3D structure of the enzyme molecule, particularly the active site where substrate molecules bind.

(C) Most enzymes are globular proteins. - This statement is correct. The vast majority of enzymes are indeed globular proteins. This means they are folded into a compact shape which is crucial for their function. Their globular structure allows for the creation of specific active sites where the chemical reactions take place.

(D) Enzyme - oxidase catalyses the hydrolysis of maltose into glucose. - This statement is incorrect. The enzyme that catalyses the hydrolysis of maltose into glucose is maltase, not oxidase. Oxidases are a class of enzymes that catalyze the transfer of electrons to oxygen, and are involved in oxidation reactions, not in the hydrolysis of sugars.

Therefore, the incorrect statements regarding enzymes are (B) Enzymes are non-specific and can catalyse different kinds of reactions, and (D) Enzyme - oxidase catalyses the hydrolysis of maltose into glucose, making Option A the correct choice.

Are bases of DNA molecule. As DNA contain four bases, which are adenine, guanine, cytosine and thymine.

The coagulation of an egg on heating is because of Option A: Denaturation of protein occurs. When an egg is heated, the proteins in the egg (primarily albumins) undergo denaturation. This process involves the structural alteration of the protein molecules without breaking the peptide bonds that hold the amino acid sequences together. Denaturation causes the proteins to unfold and then aggregate into a new, solid structure, which is what you observe as the egg white and yolk changing from liquid to solid. This change is principally caused by the disruption of non-covalent bonds in the protein, such as hydrogen bonds, ionic bonds, and hydrophobic interactions.

Option B is incorrect because the biological property of the protein does indeed change during the process. The protein in its denatured (coagulated) form does not function in the same way as it did in its native form.

Option C is also incorrect because the primary structure of the protein, defined by its amino acid sequence linked by peptide bonds, remains unaltered during denaturation. The process does not involve the breaking of these peptide linkages.

Lastly, Option D is incorrect because the secondary structure of the protein, which includes α-helices and β-pleated sheets formed by hydrogen bonding, typically undergoes significant alteration during denaturation, contributing to the observable change in the egg's texture.

The ninhydrin test is a chemical test which is used to detect the presence of amino acids or proteins. When amino acids or proteins react with ninhydrin, a deep blue or purple color is produced, which is indicative of a positive test. This reaction primarily occurs due to the reaction of ninhydrin with the free amino groups (-NH₂) present in amino acids or proteins.

Let's examine each option:

Option A: Polyvinyl chloride - Polyvinyl chloride, commonly known as PVC, is a synthetic polymer. It does not contain amino acids or free amino groups. Therefore, it does not give a positive test with ninhydrin.

Option B: Cellulose - Cellulose is a carbohydrate polymer consisting of glucose units. It is the main constituent of the cell wall in plants. Like PVC, cellulose does not contain amino acids or free amino groups, so it also does not give a positive test with ninhydrin.

Option C: Egg albumin - Egg albumin is a protein found in egg whites. Proteins are made up of amino acids linked by peptide bonds, and free amino groups are present in the structure of proteins. Therefore, egg albumin reacts with ninhydrin and gives a positive test by producing a deep blue or purple color.

Option D: Starch - Starch is a polysaccharide composed of glucose units and is a carbohydrate like cellulose. It does not possess amino acids or free amino groups. Consequently, starch does not give a positive test with ninhydrin.

Based on the explanation, the correct answer is Option C: Egg albumin, as it is the only option among the ones listed that contains proteins, which have free amino groups capable of reacting with ninhydrin to give a positive test.

$\alpha$-Glucose and $\alpha$-Galactose differ in configuration of one asymmetric carbon. Thus they are epimers.

$\alpha$ and $\beta$-glucose differ at anomeric carbon. Thus they are anomers.

$\alpha$-Glucose and $\alpha$-Fructose have different functional groups. Thus they are functional isomers.

A (adenine) pairs with T (thymine)

T (thymine) pairs with A (adenine)

G (guanine) pairs with C (cytosine)

C (cytosine) pairs with G (guanine)

T (thymine) pairs with A (adenine)

T (thymine) pairs with A (adenine)

C (cytosine) pairs with G (guanine)

A (adenine) pairs with T (thymine)

1. A pairs with T

2. T pairs with A

3. G pairs with C

4. C pairs with G

5. T pairs with A

6. T pairs with A

7. C pairs with G

8. A pairs with T

Glucose $\xrightarrow[\Delta]{\mathrm{NaHCO}_3}$ no reaction

Glucose $\xrightarrow[\Delta]{\mathrm{HNO}_3}$ saccharic acid

Glucose $\xrightarrow[\Delta]{\mathrm{HI}}$ n-hexane

Glucose $\xrightarrow[\Delta]{\mathrm{Br}_2}$ Gluconic acid

Sucrose do not contain hemiacetal group.

Hence it does not give test with Fehling solution.

While all other give positive test with Fehling solution

A-II, B-III, C-I, D-IV

Fact based.

Proteins are natural polymers composed of $\alpha$-amino acids which are connected by peptide linkages.

Hence proteins upon acidic hydrolysis produce $\alpha$-amino acids.

The structure of protein that remains intact after the coagulation of egg white on boiling is the Primary structure. The correct answer is Option B.

The primary structure of a protein is the sequence of amino acids that are linked by peptide bonds. This sequence dictates the protein's higher levels of structure including secondary, tertiary, and quaternary structures. Regardless of the change in the protein's conformation due to denaturation (such as what happens during boiling of egg white), the sequence of amino acids remains the same since the peptide bonds do not get broken under such conditions.

When egg white is boiled, the proteins denature, which means the structure of the protein becomes altered due to the breakdown of non-covalent interactions that hold the protein's higher-order structures together. This includes:

• Secondary structure: This involves hydrogen bonding within the peptide backbone, producing structures such as alpha-helices and beta-sheets.


• Tertiary structure: This involves the overall three-dimensional folding of the protein, driven by interactions such as hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bridges.


• Quaternary structure: This involves the arrangement and interactions of multiple protein subunits in a multi-subunit complex.

During coagulation caused by heat, the weak hydrogen and ionic bonds of secondary and tertiary structures are broken and the proteins can aggregate or form gel-like structures, changing the consistency of the egg white. However, the covalent peptide bonds of the primary structure stay intact throughout this process.

Phosphodiester linkage

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).

The one-letter code for each amino acid is as follows:

Glutamic Acid (A) is represented by the letter E (III).

Glutamine (B) is represented by the letter Q (I).

Tyrosine (C) is represented by the letter Y (IV).

Tryptophan (D) is represented by the letter W (II).

These one-letter codes are part of the standard notation used in biology and biochemistry to represent the 20 standard amino acids, plus a few others. The codes are designed to be short and easy to remember, while still being distinct from each other.