Biomacromolecuals Questions in English

(A) Assertion $(A)$: Polysaccharides are indeed long chains of monosaccharides (sugars) linked together by glycosidic bonds. This statement is true.
Reason $(R)$: Cellulose is a structural polysaccharide made of glucose units and is a major structural component of the plant cell wall. This statement is also true.
Since both statements are scientifically accurate,the correct option is that both $A$ and $R$ are true.

(B) Macromolecules are large,complex molecules with a high molecular weight,typically formed by the polymerization of smaller subunits called monomers.
In biological systems,proteins,polysaccharides,and nucleic acids are classified as macromolecules.
Amino acids are the monomers of proteins.
Monosaccharides,such as glucose,are the monomers of polysaccharides.
Therefore,among the given options,$Protein$ is a macromolecule.

(A) $ATP$ (Adenosine Triphosphate) is known as the energy currency of the cell.
It stores chemical energy in its high-energy phosphate bonds.
When the cell requires energy for various metabolic processes,$ATP$ is hydrolyzed to $ADP$ (Adenosine Diphosphate) and inorganic phosphate,releasing energy.

(N/A) Macromolecules are large,complex molecules that exist in a colloidal state within the intercellular fluid. They are formed by the polymerization of micromolecules,which are molecules with low molecular weight. Common examples of macromolecules include polysaccharides,proteins,and nucleic acids.

$\rightarrow$ All those compounds found in the acid-soluble pool have molecular weights ranging from $18$ to $800$ Daltons (Da). These are known as micromolecules or biomolecules of low molecular weight.
$\rightarrow$ The acid-insoluble fraction contains four types of organic compounds: proteins, nucleic acids, polysaccharides, and lipids. With the exception of lipids, these have molecular weights in the range of $10,000$ Daltons and above. These are known as biomacromolecules.
$\rightarrow$ Biomolecules are classified based on their molecular weight: $(i)$ Micromolecules (molecular weight $ < 1000$ Daltons) and $(ii)$ Biomacromolecules (molecular weight $ > 1000$ Daltons).
$\rightarrow$ The molecules in the insoluble fraction, except for lipids, are polymeric substances.
$\rightarrow$ Lipids are small molecular weight compounds but are found in the acid-insoluble fraction because they form vesicles during tissue grinding, which are not water-soluble.
$\rightarrow$ Average composition of cells:

Component	% of the total cellular mass
Water	$70-90$
Proteins	$10-15$
Carbohydrates	$3$
Lipids	$2$
Nucleic acids	$5-7$
Ions	$1$

(N/A) $\rightarrow$ In a polypeptide or a protein, amino acids are linked by a peptide bond, which is formed when the carboxyl $(-COOH)$ group of one amino acid reacts with the amino $(-NH_2)$ group of the next amino acid with the elimination of a water molecule (dehydration).
$\rightarrow$ In a polysaccharide, the individual monosaccharides are linked by a glycosidic bond. This bond is also formed by dehydration between two carbon atoms of two adjacent monosaccharides.
$\rightarrow$ In a nucleic acid, a phosphate moiety links the $3'$-carbon of one sugar of one nucleotide to the $5'$-carbon of the sugar of the succeeding nucleotide. The bond between the phosphate and hydroxyl group of the sugar is an ester bond. As there is one such ester bond on either side, it is called a phosphodiester bond.
$\rightarrow$ Nucleic acids exhibit a wide variety of secondary structures, such as the Watson-Crick model of $DNA$, where two polynucleotide strands are anti-parallel and held together by hydrogen bonds between nitrogenous bases ($A=T$ with two hydrogen bonds, $G \equiv C$ with three hydrogen bonds).

(D) $\Rightarrow$ Compounds with a molecular weight less than $1000 \text{ Dalton}$ are classified as micromolecules,while those with a higher molecular weight are called macromolecules.
$\Rightarrow$ Proteins,nucleic acids,and polysaccharides are true macromolecules found in the acid-insoluble fraction.
$\Rightarrow$ Lipids have a molecular weight of less than $1000 \text{ Dalton}$,which would typically classify them as micromolecules.
$\Rightarrow$ However,during the process of grinding tissue in trichloroacetic acid,the cell membrane and other membranes are broken into vesicles that are not water-soluble.
$\Rightarrow$ Consequently,these lipid-containing vesicles are separated along with the acid-insoluble fraction (macromolecules) rather than the acid-soluble pool. Therefore,they are studied along with biomacromolecules.

(N/A) The basic needs of all living organisms are essentially the same. They require macromolecules such as carbohydrates,proteins,and fats,along with water and minerals,for their growth,development,and metabolic activities. These macromolecules serve as energy sources and structural components of cells.

(B) Cellulose is a polysaccharide consisting of a linear chain of several hundred to many thousands of $\beta$-$D$-glucose units.
In biological contexts,a typical cellulose molecule is formed by the polymerisation of approximately $6000$ molecules of $\beta$-glucose linked by $\beta-1, 4$-glycosidic bonds.

(D) Vitamin-$C$ is chemically known as ascorbic acid.
It is primarily obtained from citrus fruits such as lemon,orange,amla,and guava.
Vitamin-$C$ plays a crucial role in the formation of normal collagen,bone matrix,tooth dentine,and other extracellular materials.
It is essential for the growth and maintenance of connective tissues,cartilages,bones,and teeth.

(N/A) The term "Energy Currency" refers to a molecule that stores and provides energy for various cellular processes. $ATP$ (Adenosine Triphosphate) is known as the energy currency of the cell because it stores energy in its high-energy phosphate bonds, which can be readily released when needed.
In plants and animals, $ATP$ acts as the primary energy currency. While other molecules like $GTP$, $CTP$, and $UTP$ can also act as energy donors, $ATP$ is the most universal.
The hydrolysis of $ATP$ into $ADP$ and inorganic phosphate $(Pi)$ releases approximately $7.3 \text{ kcal/mol}$ of energy, which powers various biochemical processes.
$ATP$ functions effectively as an energy carrier because:
$(i)$ Energy is stored in small, manageable packets, minimizing energy loss during transport.
$(ii)$ It can be easily transported from the site of production to the site of utilization within the cell.
$(iii)$ It provides a continuous and immediate supply of energy for essential cellular tasks.

(A) From a chemical perspective $(P)$,biomolecules are classified based on their functional groups and chemical structures,such as aldehydes,ketones,and aromatic compounds.
From a biological perspective $(Q)$,biomolecules are classified based on their role as building blocks of life,such as amino acids (for proteins),nucleotide bases (for nucleic acids),and fatty acids (for lipids).
Therefore,the correct classification is $P$ = Aldehydes,ketones,aromatic compounds and $Q$ = Amino acids,nucleotide bases,fatty acids. This corresponds to option $A$.

(D) During the chemical analysis of living tissues using trichloroacetic acid $(Cl_3CCOOH)$,the tissue is ground to form a slurry.
When this slurry is filtered,two fractions are obtained:
$1$. The filtrate,which is the acid-soluble pool,contains small molecular weight compounds (monomers like amino acids,sugars,nucleotides).
$2$. The retentate,which is the acid-insoluble fraction (also called the residue),contains macromolecules like polysaccharides,proteins,nucleic acids,and lipids.
Since polysaccharides are macromolecules,they are found in the acid-insoluble fraction,which is also referred to as the residue.
Therefore,both $B$ and $C$ refer to the same fraction.

(C) Cellulose is a homopolymer composed exclusively of $D$-glucose units linked by $\beta-1,4$-glycosidic bonds.
Since it consists of only one type of monomer unit,it is classified as a homopolymer,not a heteropolymer.
Therefore,the statement '$C$' is incorrect.
All other statements are correct: Cellulose is the primary structural component of plant cell walls,paper is derived from plant pulp (cellulose),and cotton fibers are nearly pure cellulose.

(A) When tissues are ground in trichloroacetic acid $(TCA)$,the chemical analysis results in two fractions.
$1$. The filtrate,which is the acid-soluble pool,contains small molecular weight compounds known as micro-biomolecules (e.g.,amino acids,simple sugars,nucleotides).
$2$. The retentate,which is the acid-insoluble fraction,contains large molecular weight compounds known as macro-biomolecules (e.g.,proteins,nucleic acids,polysaccharides,lipids).
Therefore,$P$ represents micro-biomolecules and $Q$ represents macro-biomolecules.

(A) $ATP$ (Adenosine Triphosphate) is known as the energy currency of the cell.
It stores energy in its high-energy phosphate bonds.
When the cell requires energy for various metabolic processes,$ATP$ is hydrolyzed into $ADP$ (Adenosine Diphosphate) and inorganic phosphate,releasing the stored energy.

(D) The molecule shown in the image consists of an adenine base,a ribose sugar,and three phosphate groups attached to the sugar.
This structure is characteristic of Adenosine Triphosphate $(ATP)$.
$ADP$ (Adenosine Diphosphate) would have only two phosphate groups.
$NADP$ (Nicotinamide Adenine Dinucleotide Phosphate) has a more complex structure involving a nicotinamide ring.
$FMN$ (Flavin Mononucleotide) is a derivative of riboflavin and has a different structure.

(D) The image shows the oxidized and reduced forms of Nicotinamide Adenine Dinucleotide $(NAD)$.
In the left structure,the nicotinamide ring has a positive charge on the nitrogen atom,indicating the oxidized form,which is $NAD^+$.
In the right structure,the nicotinamide ring has gained two hydrogen atoms (one as a hydride ion),resulting in the reduced form,which is $NADH$.
Therefore,the correct sequence is $NAD^+$ and $NADH$.

(B) Biomacromolecules are organic compounds with a high molecular weight,typically exceeding $10,000 \ Da$.
Proteins,nucleic acids,and polysaccharides are polymers formed by the linkage of many monomeric units,thus qualifying as macromolecules.
Lipids,although often found in the acid-insoluble fraction along with macromolecules,have a molecular weight generally less than $800 \ Da$.
Therefore,lipids are not considered true biomacromolecules.

(D) Biomacromolecules are organic compounds with a molecular weight generally exceeding $10,000$ Daltons.
Cellulose is a polysaccharide (a polymer of glucose) and is considered a biomacromolecule.
Haemoglobin is a protein (a polymer of amino acids) with a high molecular weight,thus it is also a biomacromolecule.
Phospholipids have a lower molecular weight compared to polysaccharides and proteins,so they are generally classified as lipids rather than biomacromolecules.
Therefore,both Cellulose and Haemoglobin are biomacromolecules.

(A) Water $(H_2O)$ is a polar molecule due to the electronegativity difference between oxygen and hydrogen atoms.
This polarity allows the formation of hydrogen bonds between adjacent water molecules.
These hydrogen bonds are responsible for unique properties of water such as high specific heat,cohesion,adhesion,surface tension,and its role as a universal solvent.
Peptide bonds are found in proteins,glycosidic bonds in carbohydrates,and disulphide bonds in protein tertiary structures,none of which are present between water molecules.