Nucleic acids Questions in English

(D) Nucleic acids,specifically $DNA$ and $RNA$,are the largest macromolecules found in living organisms. $DNA$ molecules can reach extremely high molecular weights,often consisting of millions of base pairs,making them significantly larger than typical proteins,carbohydrates,or lipids.

(D) nucleotide consists of a nitrogenous base,a pentose sugar,and a phosphate group.
Ribose sugar is present in $RNA$ nucleotides,while deoxyribose sugar is present in $DNA$ nucleotides.
$RNA$ contains the nitrogenous bases Adenine,Guanine,Cytosine,and Uracil.
$DNA$ contains the nitrogenous bases Adenine,Guanine,Cytosine,and Thymine.
Thymine is specific to $DNA$ (deoxyribose),whereas Uracil is specific to $RNA$ (ribose).
Therefore,a nucleotide containing Uracil must contain ribose sugar.

(D) Nucleic acids are polymers of nucleotides.
Each nucleotide consists of three components: a pentose sugar,a phosphoric acid group,and a nitrogenous base.
Therefore,complete hydrolysis of nucleic acids yields all three components: sugar,phosphoric acid,and nitrogenous bases.
Thus,the correct option is $D$.

(B) Nitrogenous bases are classified into two types: purines and pyrimidines.
Purines are double-ring structures,which include Adenine $(A)$ and Guanine $(G)$.
Pyrimidines are single-ring structures,which include Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$.
Therefore,Guanine is a purine.

(A) $ATP$ stands for Adenosine Triphosphate. It is a nucleotide consisting of an adenine base,a $D$-ribose sugar,and three phosphate groups. The sugar component in $ATP$ is always the $D$-isomer of ribose,which is the naturally occurring form in biological systems.

(A) $ATP$ stands for Adenosine Triphosphate. It consists of an adenine base,a ribose sugar,and three phosphate groups. Since it is composed of a nitrogenous base,a pentose sugar,and phosphate groups,it is classified as a nucleotide.

(C) Nucleic acids consist of nitrogenous bases,which are classified into two types: Purines and Pyrimidines.
Purines include Adenine $(A)$ and Guanine $(G)$.
Pyrimidines include Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$.
Therefore,Thymine is a Pyrimidine.

(A) Pyrimidines are heterocyclic aromatic organic compounds similar to benzene and pyridine,containing two nitrogen atoms at positions $1$ and $3$ of the six-membered ring.
They consist of a single six-membered ring structure.
In contrast,purines are double-ring compounds consisting of a pyrimidine ring fused to an imidazole ring.
Therefore,pyrimidines are single-ring compounds.

(D) Nucleic acids were first identified by Friedrich Miescher in $1869$. He isolated them from the nuclei of pus cells and named the substance 'nuclein'.

(B) Nucleic acids are of two types: $DNA$ (Deoxyribonucleic acid) and $RNA$ (Ribonucleic acid).
$DNA$ contains $2$-deoxyribose sugar,while $RNA$ contains ribose sugar.
Both are pentose sugars (five-carbon sugars).
Among the given options,ribose is the pentose sugar found in $RNA$ molecules.

(B) Purines are heterocyclic aromatic organic compounds that consist of a pyrimidine ring fused to an imidazole ring.
This structure results in a double-ring system.
Examples of purines include adenine and guanine,which are nitrogenous bases found in nucleic acids ($DNA$ and $RNA$).

(C) Nucleic acids,which include $DNA$ and $RNA$,contain nitrogenous bases (purines and pyrimidines) that possess conjugated double bonds.
These structures allow nucleic acids to absorb ultraviolet $(UV)$ light efficiently.
The maximum absorbance for nucleic acids occurs at a wavelength of approximately $260\, \text{nm}$.
This property is widely used in laboratory settings to quantify the concentration of $DNA$ or $RNA$ in a sample using a spectrophotometer.

(B) The nitrogenous bases are classified into two types: purines and pyrimidines.
Purines (Adenine and Guanine) consist of a double-ring structure containing four nitrogen atoms in the rings.
However,Guanine specifically has an additional nitrogen atom in its amino group or side chain,but the question asks for the ring structure. Actually,looking at the molecular structure of Guanine $(C_5H_5N_5O)$,it contains five nitrogen atoms in total,with four nitrogen atoms forming part of the fused heterocyclic ring system (a pyrimidine ring fused to an imidazole ring).
Uracil,Cytosine,and Thymine are pyrimidines,which contain only two nitrogen atoms in their single-ring structure.
Therefore,Guanine is the correct answer as it contains five nitrogen atoms.

(A) nucleic acid is a polymer of nucleotides,which are composed of a nitrogenous base,a pentose sugar,and a phosphoric acid group.
When a nucleotide lacks the phosphoric acid group,it is referred to as a nucleoside.
Therefore,a nucleoside consists only of a nitrogenous base and a sugar molecule.
Thus,the correct option is $A$.

(D) In nucleic acids, there are four types of nucleotides commonly found in each type of nucleic acid ($DNA$ and $RNA$).
For $DNA$, the four nucleotides are:
$(i)$ Deoxycytidylic acid (deoxycytidylate)
(ii) Deoxythymidylic acid (deoxythymidylate)
(iii) Deoxyadenylic acid (deoxyadenylate)
(iv) Deoxyguanylic acid (deoxyguanylate)
For $RNA$, the four nucleotides are:
$(i)$ Cytidylic acid (cytidylate)
(ii) Uridylic acid (uridylate)
(iii) Adenylic acid (adenylate)
(iv) Guanylic acid (guanylate)
Therefore, the correct answer is $Four$.

(D) nucleoside is a chemical compound consisting of a nitrogenous base linked to a pentose sugar (either ribose or deoxyribose) via a glycosidic bond.
When a phosphate group is added to a nucleoside,it becomes a nucleotide.
Therefore,a nucleoside consists of a sugar and a nitrogenous base.

(B) $RNA$ is widely distributed in a cell because it is found in the nucleus (as part of the nucleolus),in the cytoplasm,and as a component of ribosomes. In contrast,$DNA$ is primarily restricted to the nucleus,mitochondria,and chloroplasts. Chloroplasts and chromoplasts are specific organelles with limited distribution.

(C) Phosphorus is a key structural component of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
The phosphate group is linked to the sugar via a phosphodiester bond,which is essential for the structure of $DNA$ and $RNA$.

(D) $ATP$ (Adenosine Triphosphate) consists of an adenine base,a ribose sugar,and three phosphate groups.
The high-energy bonds in $ATP$ are the phosphoanhydride bonds that link the phosphate groups together.
These bonds are specifically located between the oxygen atom of one phosphate group and the phosphorus atom of the adjacent phosphate group ($O-P$ bonds).
Therefore,the high-energy bonds are $O-P$ bonds.

(A) $ATP$ (Adenosine Triphosphate) is a nucleotide derivative.
It consists of an adenine nitrogenous base,a ribose sugar,and three phosphate groups.
Since $RNA$ is composed of ribonucleotides (which also contain ribose sugar and nitrogenous bases),$ATP$ is structurally most similar to a monomeric unit of $RNA$.

(B) $RNA$ (Ribonucleic acid) is a polymer composed of nucleotides. Each nucleotide consists of a nitrogenous base,a ribose sugar,and a phosphate group.
$1$. The chemical formula of the ribose sugar is $C_5H_{10}O_5$,which contains Carbon,Hydrogen,and Oxygen.
$2$. The nitrogenous bases (Adenine,Guanine,Cytosine,Uracil) contain Carbon,Hydrogen,Nitrogen,and Oxygen.
$3$. The phosphate group $(PO_4^{3-})$ contains Phosphorus and Oxygen.
Sulfur is not a constituent element of the nucleotides that make up $RNA$.

(D) Uridine monophosphate $(UMP)$ is a nucleotide consisting of the nitrogenous base uracil,the sugar ribose,and a phosphate group.
Since uracil is a nitrogenous base specific to $RNA$ and not $DNA$,uridine monophosphate is a fundamental component of $RNA$ molecules.
Therefore,the correct option is $D$.

(A) nucleoside consists of a nitrogenous base and a pentose sugar.
In contrast,a nucleotide consists of a nitrogenous base,a pentose sugar,and a phosphate group.
Therefore,a nucleoside differs from a nucleotide by the absence of a phosphate group.

(D) Phosphorus is a fundamental component of nucleic acids ($DNA$ and $RNA$).
It exists in the form of a phosphate group $(PO_4^{3-})$ which links the sugar molecules of the nucleotide backbone via phosphodiester bonds.
Proteins generally do not contain phosphorus unless they are phosphorylated (e.g.,phosphoproteins),but it is a structural requirement for all $DNA$ and $RNA$ molecules.
Therefore,both $DNA$ and $RNA$ contain phosphorus.

(C) Nucleotides are the fundamental building blocks or monomeric units of nucleic acids ($DNA$ and $RNA$).
Each nucleotide consists of three distinct components:
$1$. $A$ nitrogenous base (Purines or Pyrimidines).
$2$. $A$ pentose sugar (Ribose or Deoxyribose).
$3$. $A$ phosphate group (derived from phosphoric acid).
Therefore,the correct composition is Base-sugar-phosphate.

(A) The correct answer is $A$.
Nucleic acids ($DNA$ and $RNA$) are polymers of nucleotides.
$A$ nucleotide consists of three components: a nitrogenous base (purine or pyrimidine),a pentose sugar (ribose or deoxyribose),and a phosphate group.
$A$ nucleoside consists only of a nitrogenous base and a pentose sugar,lacking the phosphate group.
Therefore,the repeating structural unit of a nucleic acid is a nucleotide.

(D) Nucleic acids ($DNA$ and $RNA$) are considered the "Secret of life" because they store and transmit the genetic information required for the development, functioning, growth, and reproduction of all living organisms.
They act as the blueprint for life, directing the synthesis of proteins which carry out the essential biological processes.

(D) $A.T.P.$ stands for Adenosine Triphosphate.
It is a nucleotide consisting of an adenine base,a ribose sugar,and three phosphate groups.
The bonds between the phosphate groups are high-energy phosphoanhydride bonds.
When these bonds are hydrolyzed,a significant amount of energy is released,which is used by the cell for various metabolic activities.
Therefore,$A.T.P.$ is known as the energy currency of the cell because it stores energy in its high-energy phosphate bonds.

(C) $Nucleotide$ is the basic structural unit of nucleic acids ($DNA$ and $RNA$).
It consists of three components:
$1$. $A$ nitrogenous base (purine or pyrimidine).
$2$. $A$ pentose sugar (ribose or deoxyribose).
$3$. $A$ phosphate group.
When a nitrogenous base is linked to a pentose sugar,it forms a $Nucleoside$. When a phosphate group is added to this $Nucleoside$,it becomes a $Nucleotide$.

(A) $ATP$ stands for Adenosine Triphosphate. It consists of an adenine base,a ribose sugar,and three phosphate groups. Since it is a nitrogenous base attached to a sugar and phosphate groups,it is classified as a nucleotide.

(D) Nucleic acids ($DNA$ and $RNA$) are macromolecules formed by the polymerization of repeating units called nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
Therefore,nucleic acids are polymers of nucleotides.

(B) Nitrogenous bases in nucleic acids are classified into two categories: Purines and Pyrimidines.
$1$. Purines are double-ring structures,which include Adenine $(A)$ and Guanine $(G)$.
$2$. Pyrimidines are single-ring structures,which include Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$.
In option $B$,Adenine is a Purine,but Thymine is a Pyrimidine. Therefore,the pair 'Adenine,Thymine - Purines' is incorrectly matched.

(A, B) Nucleic acids contain nitrogenous bases which are classified into two types: purines and pyrimidines.
Purines are double-ring structures,which include Adenine $(A)$ and Guanine $(G)$.
Pyrimidines are single-ring structures,which include Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$.
In the given options,both Adenine and Guanine are purines. However,since the question asks to identify a purine and both $A$ and $B$ are correct,typically in such multiple-choice questions,we select the most appropriate one or note that both are purines. Given the standard structure,both Adenine and Guanine are purines.

(D) $DNA$ $(Deoxyribonucleic \text{ acid})$ is a type of nucleic acid.
$1$. It is a large molecule with a high molecular weight, hence it is classified as a biomacromolecule.
$2$. Due to the presence of phosphate groups in its backbone, it exhibits acidic properties.
$3$. Structurally, it is a long chain (polymer) consisting of repeating units called nucleotides.
Therefore, all the given statements are correct.

(D) Nucleic acids ($DNA$ and $RNA$) are polymers of nucleotides.
Each nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group.
$1$. $H$-bonds are present between the nitrogenous bases of the two strands in $DNA$ (e.g., $A=T$, $G \equiv C$).
$2$. Glycosidic bonds (specifically $N$-glycosidic linkages) connect the nitrogenous base to the pentose sugar.
$3$. Ester bonds (specifically phosphodiester bonds) connect the phosphate group to the sugar molecule.
$4$. Peptide bonds are characteristic of proteins, which are polymers of amino acids, and are not found in nucleic acids.

(C) Nucleic acids ($DNA$ and $RNA$) contain five main types of nitrogenous bases.
These are categorized into two groups:
$1$. Purines: Adenine $(A)$ and Guanine $(G)$.
$2$. Pyrimidines: Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$.
$DNA$ contains $A, G, C,$ and $T$,while $RNA$ contains $A, G, C,$ and $U$.
Therefore,there are $5$ distinct types of nitrogenous bases found in nucleic acids.

(A) Nucleic acids are of two types: $DNA$ (Deoxyribonucleic acid) and $RNA$ (Ribonucleic acid).
In $DNA$,the nitrogenous bases are Adenine,Guanine,Cytosine,and Thymine.
Thymine is chemically known as $5$-methyluracil.
$RNA$ contains Uracil instead of Thymine.
Therefore,Thymine (methylated uracil) is specifically found in $DNA$.

(D) Nucleic acids are composed of nitrogenous bases,pentose sugars,and phosphate groups.
In $DNA$,the four nitrogenous bases are Adenine $(A)$,Guanine $(G)$,Cytosine $(C)$,and Thymine $(T)$.
In $RNA$,the four nitrogenous bases are Adenine $(A)$,Guanine $(G)$,Cytosine $(C)$,and Uracil $(U)$.
Thymine is present in $DNA$ but is replaced by Uracil in $RNA$.
Therefore,Uracil is the nitrogenous base found exclusively in $RNA$.

(C) Nucleic acids,specifically $DNA$ and $RNA$,are essential biomolecules.
$DNA$ is primarily located within the nucleus of eukaryotic cells,while $RNA$ is found in both the nucleus and the cytoplasm.
Additionally,$RNA$ is a key component of ribosomes.
Therefore,nucleic acids are present in both the nucleus and the cytoplasm of the cell.

(D) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar.
When a phosphate group is added to a nucleoside,it forms a nucleotide.
Therefore,the composition of a nucleoside is $Sugar + Base$.

(B) nucleotide is the basic building block of nucleic acids ($DNA$ and $RNA$).
Each nucleotide consists of three distinct chemical components:
$1$. $A$ nitrogenous base (purine or pyrimidine).
$2$. $A$ pentose sugar (ribose in $RNA$ or deoxyribose in $DNA$).
$3$. $A$ phosphate group.
These three components are linked together to form a single nucleotide unit. Therefore,the correct composition is Base - Sugar - Phosphate.

(D) Nucleic acids,such as $DNA$ and $RNA$,are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
Therefore,the fundamental repeating unit of a nucleic acid is the nucleotide.

(A) nucleoside consists of a nitrogenous base linked to a pentose sugar.
$A$ nucleotide is formed when a phosphate group is added to a nucleoside.
Therefore,the fundamental difference between a nucleoside and a nucleotide is the presence of a phosphate group in the nucleotide,which is absent in the nucleoside.

(A) Nucleic acids ($DNA$ and $RNA$) are polymers of nucleotides.
Each nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
$A$ nucleoside consists only of a nitrogenous base and a pentose sugar,lacking the phosphate group.
Therefore,the fundamental repeating unit that polymerizes to form nucleic acids is the nucleotide.

(A) nucleotide is the basic structural unit of nucleic acids ($DNA$ and $RNA$).
It consists of three essential components:
$1$. $A$ nitrogenous base (purine or pyrimidine).
$2$. $A$ pentose sugar (ribose in $RNA$ or deoxyribose in $DNA$).
$3$. $A$ phosphate group (derived from phosphoric acid).
When a nitrogenous base is linked to a pentose sugar,it is called a nucleoside. When a phosphate group is added to a nucleoside,it forms a nucleotide.

(B) High-energy nucleotides,such as $ATP$ (Adenosine triphosphate),$GTP$ (Guanosine triphosphate),etc.,are characterized by the presence of multiple phosphate groups attached to the sugar moiety.
These phosphate groups are linked by high-energy phosphoanhydride bonds.
When these bonds are hydrolyzed,a significant amount of energy is released,which is used to drive various cellular processes.
Therefore,the defining feature of high-energy nucleotides is the presence of more than one phosphate group.

(A) Nucleic acids,such as $DNA$ and $RNA$,are long-chain macromolecules known as polynucleotides.
These are formed by the polymerization of repeating units called nucleotides.
$A$ single nucleotide consists of three components: a nitrogenous base,a pentose sugar (ribose or deoxyribose),and a phosphate group.
Therefore,nucleic acids are polymers of nucleotides.

(C) In a nucleotide,the phosphate group is linked to the $5'$-carbon of the sugar (pentose sugar) through a covalent bond known as an ester bond.
Specifically,when a phosphate group connects to the sugar,it forms a phosphoester linkage.
Since the question asks for the bond between phosphate and sugar in a single nucleotide,it is a covalent phosphoester bond.
Among the given options,'Covalent bond' is the most accurate description of the linkage between the phosphate and the sugar moiety.