Nucleic acids Questions in English

(D) The correct set is $D$.
$1$. Malleus,Incus,and Stapes are ear ossicles; Cochlea is a part of the inner ear,so option $A$ is incorrect.
$2$. Ilium,Ischium,and Pubis are the three bones that fuse to form the coxal bone of the pelvic girdle,so option $B$ is correct.
$3$. Actin and Myosin are contractile muscle proteins,while Rhodopsin is a visual pigment found in the retina,so option $C$ is incorrect.
$4$. Cytosine,Uracil,and Thymine are all nitrogenous bases belonging to the Pyrimidine category,so option $D$ is correct.
Note: In the provided options,both $B$ and $D$ are biologically correct. However,in the context of standard biology questions regarding biomolecules,$D$ is the most direct classification of nitrogenous bases.

(A) phosphodiester bond is a chemical bond that links the $3'$ carbon atom of one sugar molecule and the $5'$ carbon atom of another in deoxyribonucleic acid $(DNA)$ and ribonucleic acid $(RNA)$.
These bonds are the structural backbone of nucleic acids,connecting individual nucleotides together.
In contrast,diglycerides contain ester bonds,polysaccharides contain glycosidic bonds,and polypeptides contain peptide bonds.

(A) Nucleotides consist of carbon,hydrogen,oxygen,nitrogen,and phosphorus.
Nitrogenous bases are classified as purines or pyrimidines.
Purines (Adenine and Guanine) are $9$-membered double-ringed structures containing $4$ nitrogen atoms.
Pyrimidines (Cytosine,Thymine,and Uracil) are single-ringed structures.
Specifically,Cytosine has $3$ nitrogen atoms,while Uracil and Thymine have $2$ nitrogen atoms.
Therefore,the statement that Adenine has $4$ nitrogen atoms is correct.

(A) By analyzing the chemical structures of the nitrogenous bases:
$A$ is Uracil,a pyrimidine base found in $RNA$.
$B$ is Adenine,a purine base.
$C$ is Thymine,a pyrimidine base with a methyl group $(-CH_3)$ at the $5^{th}$ position.
$D$ is Guanine,a purine base.
$E$ is Cytosine,a pyrimidine base.
Therefore,the correct combination is $A-$ uracil,$B-$ adenine,$C-$ thymine,$D-$ guanine,$E-$ cytosine.

(A) Nucleotides are the building blocks of nucleic acids.
Each nucleotide consists of three distinct components:
$1$. $A$ pentose sugar (ribose in $RNA$ or deoxyribose in $DNA$).
$2$. $A$ phosphate group.
$3$. $A$ nitrogenous base (purine or pyrimidine).
Therefore,a nucleotide is formed by the combination of a base,a sugar,and a phosphate group.

(N/A) Heterocyclic compounds are organic compounds that contain at least one atom other than carbon (such as nitrogen,oxygen,or sulfur) within their ring structure.
In living organisms,many important biomolecules contain heterocyclic rings. Nitrogenous bases are classic examples of such compounds.
Nitrogenous bases include purines (e.g.,Adenine,Guanine) and pyrimidines (e.g.,Cytosine,Uracil,Thymine).
When a nitrogenous base is attached to a sugar molecule,it forms a nucleoside (e.g.,Adenosine,Guanosine,Thymidine,Uridine,Cytidine).
When a phosphate group is also esterified to the sugar of a nucleoside,it forms a nucleotide (e.g.,Adenylic acid,Thymidylic acid,Guanylic acid,Uridylic acid,Cytidylic acid).
Nucleic acids like $DNA$ and $RNA$ are polymers of nucleotides and serve as the genetic material in living organisms.

(N/A) $\rightarrow$ In the acid-insoluble fraction of any living tissue,the other type of macromolecule is the nucleic acid.
$\rightarrow$ Together with polysaccharides and polypeptides,these comprise the true macromolecular fraction of any living cell/tissue.
$\rightarrow$ $A$ nucleotide is the building block for nucleic acid. Each nucleotide is formed by three different components: $(i)$ Heterocyclic compound - Nitrogenous base,$(ii)$ Monosaccharide,$(iii)$ Phosphoric acid/phosphate.
$\rightarrow$ The heterocyclic compounds in nucleic acids are the nitrogenous bases: Adenine,Guanine,Uracil,Cytosine,and Thymine. Adenine and Guanine are substituted purines,while Uracil,Cytosine,and Thymine are substituted pyrimidines.
$\rightarrow$ The sugar found in polynucleotides is either ribose or $2^{\prime}$-deoxyribose.
$\rightarrow$ $A$ nucleic acid containing deoxyribose is called deoxyribonucleic acid $(DNA)$,while that which contains ribose is called ribonucleic acid $(RNA)$.

(N/A)

Purine	Pyrimidine
$(1)$ It consists of a double-ring structure.	$(1)$ It consists of a single-ring structure.
$(2)$ It contains $5$ carbon atoms in its heterocyclic ring system.	$(2)$ It contains $4$ carbon atoms in its heterocyclic ring system.
$(3)$ Examples include Adenine and Guanine.	$(3)$ Examples include Cytosine,Uracil,and Thymine.

(N/A) The differences between a nucleoside and a nucleotide are as follows:
| Feature | Nucleoside | Nucleotide |
| :--- | :--- | :--- |
| Composition | Formed by the linkage of a pentose sugar and a nitrogenous base. | Formed by the linkage of a pentose sugar,a nitrogenous base,and a phosphate group. |
| Formation | $A$ nitrogenous base links with a ribose sugar to form a ribonucleoside. | When a ribonucleoside links with a phosphate group,a ribonucleotide is formed. |
| Deoxy form | $A$ nitrogenous base links with a deoxyribose sugar to form a deoxyribonucleoside. | When a deoxyribonucleoside links with a phosphate group,a deoxyribonucleotide is formed. |
| Examples | Cytidine,Uridine,Adenosine,Thymidine. | $AMP$,$GMP$,$UMP$,$CMP$. |
| Structure | Consists of a sugar and a base (e.g.,Adenosine). | Consists of a sugar,a base,and a phosphate group (e.g.,Adenosine monophosphate or $AMP$). |

(N/A) $(i)$ Nucleic acids are macromolecules formed by the polymerization of nucleotides. Each nucleotide consists of three components: a nitrogenous base (heterocyclic compound),a pentose sugar (monosaccharide),and a phosphoric acid group.
$(ii)$ $A$ peptide bond is a chemical bond formed between the carboxyl group $(-COOH)$ of one amino acid and the amino group $(-NH_2)$ of the adjacent amino acid. This linkage occurs through a dehydration synthesis process,where a molecule of water is eliminated.

(N/A) $(i)$ $ATP$: Adenosine triphosphate
$(ii)$ $DNA$: Deoxyribonucleic acid
$(iii)$ $RNA$: Ribonucleic acid

(N/A) Nitrogenous bases are organic molecules containing nitrogen that form the building blocks of nucleotides. In the given list,adenine,thymine,uracil,and cytosine are nitrogenous bases.
Nucleosides are compounds formed by the attachment of a nitrogenous base to a sugar molecule (ribose or deoxyribose). In the given list,cytidine (cytosine + sugar) and guanosine (guanine + sugar) are nucleosides.

(N/A) Nucleic acids are polymeric macromolecules essential for the origin of life. The secondary structure of a nucleic acid refers to the spatial arrangement of the polynucleotide chain. $DNA$ and $RNA$ are the primary nucleic acids,and they differ significantly in their secondary structures. For example,the secondary structure of $DNA$ consists of two complementary polydeoxyribonucleotide strands that coil around a common axis to form a double-helical structure. This double-helical structure is stabilized by hydrogen bonds between complementary nitrogenous bases and hydrophobic interactions between stacked base pairs.

(N/A) nucleoside is formed by the combination of a pentose sugar and a nitrogenous base. In contrast,a nucleotide is formed when a nucleoside is linked to a phosphate group.
Key differences:
$1$. Composition: Nucleoside = Sugar + Nitrogen base; Nucleotide = Sugar + Nitrogen base + Phosphate group.
$2$. Examples of Nucleosides: Adenosine,Guanosine.
$3$. Examples of Nucleotides: Adenylic acid $(AMP)$,Guanylic acid $(GMP)$.
Structure:
- Adenosine (Nucleoside): Consists of Adenine attached to a ribose sugar at the $1'$ position.
- Adenosine monophosphate $(AMP)$ (Nucleotide): Consists of Adenine attached to a ribose sugar at the $1'$ position,with a phosphate group attached to the $5'$ carbon of the sugar.

(A) Nucleic acids are polymers of nucleotides. $DNA$ (Deoxyribonucleic acid) contains the pentose sugar deoxyribose,while $RNA$ (Ribonucleic acid) contains the pentose sugar ribose. Therefore,a nucleic acid containing deoxyribose is $DNA$.

(N/A) $(1)$ $GTP$ stands for Guanosine Triphosphate. It is a purine nucleoside triphosphate that serves as an energy source or activator of substrates in metabolic reactions.
$(2)$ $GDP$ stands for Guanosine Diphosphate. It is a nucleoside diphosphate that is formed when $GTP$ loses a phosphate group,often during energy-releasing processes.

(D) Nucleic acids are large biomolecules that play essential roles in all cells and viruses. The two primary types of nucleic acids are Deoxyribonucleic acid $(DNA)$ and Ribonucleic acid $(RNA)$.
$DNA$ serves as the genetic material in most organisms,while $RNA$ is involved in protein synthesis and gene regulation.
Proteins are polymers of amino acids,not nucleic acids.
Therefore,both $DNA$ and $RNA$ are nucleic acids.

(C) nucleotide is the basic structural unit of nucleic acids like $DNA$ and $RNA$. It consists of three distinct chemical components:
$1$. $A$ nitrogenous base (purine or pyrimidine).
$2$. $A$ pentose sugar (deoxyribose in $DNA$ or ribose in $RNA$).
$3$. $A$ phosphate group.
Therefore,the correct answer is $3$.

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

(B) nucleoside is a chemical compound formed by the combination of a pentose sugar and a nitrogenous base.
When a phosphate group is added to a nucleoside, it forms a nucleotide.
Therefore, the correct composition of a nucleoside is $Pentose \text{ } sugar + Nitrogenous \text{ } base$.

(D) Nitrogenous bases in nucleic acids are classified into two types: purines and pyrimidines.
Purines include Adenine $(A)$ and Guanine $(G)$,which are double-ring structures.
Pyrimidines include Cytosine $(C)$,Thymine $(T)$,and Uracil $(U)$,which are single-ring structures.
Since Guanine is a purine,it is not a pyrimidine.

(A) In a nucleotide,the phosphate group is attached to the $5'$-carbon of the pentose sugar through a phosphoester bond.
This bond is formed by the reaction between the hydroxyl group of the sugar and the phosphoric acid.
Note that a phosphodiester bond connects two nucleotides together,whereas the bond between a single phosphate and its sugar is a phosphoester bond.

(B) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar.
Nucleotides are formed when a phosphate group is added to a nucleoside.
$1$. Guanylic acid,Uridylic acid,and Cytidylic acid are nucleotides because they contain a phosphate group.
$2$. Adenosine is a nucleoside formed by the combination of the nitrogenous base Adenine and the sugar Ribose (or Deoxyribose).
Therefore,the correct option is $B$.

(C) $AMP$ stands for Adenosine monophosphate.
It is a nucleotide consisting of an adenine base,a ribose sugar,and a single phosphate group.
It is formed by the hydrolysis of $ATP$ (Adenosine triphosphate) or $ADP$ (Adenosine diphosphate) in biological systems.
Therefore,the correct option is $C$.

(C) In $DNA$,the nitrogenous bases are Adenine $(A)$,Guanine $(G)$,Cytosine $(C)$,and Thymine $(T)$.
Nucleotides are formed by the combination of a nitrogenous base,a pentose sugar (deoxyribose in $DNA$),and a phosphate group.
$AMP$ stands for Adenosine monophosphate,$CMP$ for Cytidine monophosphate,and $GMP$ for Guanosine monophosphate,which are all valid nucleotides found in $DNA$ or $RNA$.
$TMP$ stands for Thymidine monophosphate. In $DNA$,the nucleotide containing Thymine is specifically called Deoxythymidine monophosphate $(dTMP)$.
Since $DNA$ contains deoxyribose sugar,the term $TMP$ is technically incorrect as it implies the presence of ribose sugar (as in $RNA$),where Thymine is replaced by Uracil $(U)$. Therefore,$TMP$ is not a standard structure found in $DNA$ nomenclature.

(C) In a $DNA$ or $RNA$ molecule,nucleotides are linked together to form a polynucleotide chain.
This linkage occurs between the $3'$-carbon atom of the sugar molecule of one nucleotide and the $5'$-carbon atom of the sugar molecule of the adjacent nucleotide through a phosphate group.
This specific covalent linkage is known as a $3'-5'$ phosphodiester bond.

(D) In $DNA$,the nitrogenous bases present are Adenine $(A)$,Guanine $(G)$,Cytosine $(C)$,and Thymine $(T)$.
$RNA$ contains Uracil $(U)$ instead of Thymine $(T)$.
Deoxyribose sugar is the characteristic sugar of $DNA$,while Ribose sugar is found in $RNA$.
Therefore,'Deoxyuridylic acid' is not possible because Uracil is typically associated with Ribose sugar in $RNA$ (forming Uridylic acid),not with Deoxyribose sugar in $DNA$.

(B) nucleoside is formed by the attachment of a nitrogenous base to a sugar molecule (pentose sugar).
Structure $A$ represents a nitrogenous base (Adenine).
Structure $B$ represents a nucleoside (Adenosine),consisting of a sugar and Adenine.
Structure $C$ represents a nucleoside (Uridine),consisting of a sugar and Uracil.
Structure $D$ represents a nucleotide (Adenosine monophosphate),consisting of a sugar,Adenine,and a phosphate group.
Therefore,structures $B$ and $C$ are nucleosides. The correct option is $(B)$.

(B) nucleoside is composed of a nitrogenous base and a pentose sugar (ribose or deoxyribose).
It does not contain a phosphate group.
Nucleotides are formed when a phosphate group is attached to a nucleoside.
Among the given options,Adenosine,Guanosine,and Cytidine are nucleosides,whereas Adenylic acid,Cytidylic acid,and Guanylic acid are nucleotides.

(A) nucleotide consists of three components: a nitrogenous base,a pentose sugar,and a phosphate group.
In the provided image,structures $(A)$ and $(B)$ contain a phosphate group attached to the sugar-base complex,making them nucleotides.
Structures $(C)$ and $(D)$ lack the phosphate group and are therefore nucleosides.
Thus,$(A)$ and $(B)$ are the correct nucleotides.

(B) Nucleotides are the fundamental building blocks of nucleic acids ($DNA$ and $RNA$).
$A$ nucleotide consists of a nitrogenous base, a pentose sugar, and a phosphate group.
$Adenylic$ $acid$, $cytidilic$ $acid$, and $guanylic$ $acid$ are all examples of nucleotides because they contain a nitrogenous base, a sugar, and a phosphate group.
In contrast, $Adenosine$, $Cytidine$, and $Thymidine$ are nucleosides (base + sugar), while $Adenine$, $Cytosine$, $Uracil$, and $Thymine$ are nitrogenous bases.

(A) Nucleic acids ($RNA$ and $DNA$) are long-chain polymers composed of repeating units called nucleotides.
Each nucleotide consists of a nitrogenous base,a pentose sugar,and a phosphate group.
Therefore,they are correctly defined as polymers of nucleotides.

(B) The sugar present in $RNA$ is ribose,while the sugar present in $DNA$ is $2'$-deoxyribose.
In $\beta$-$D$-ribose (found in $RNA$),there is a hydroxyl $(-OH)$ group attached to the $2^{\text{nd}}$ carbon atom.
In $\beta$-$D$-deoxyribose (found in $DNA$),the hydroxyl group is absent at the $2^{\text{nd}}$ carbon atom,and only a hydrogen atom is present.
Therefore,the presence or absence of the hydroxyl group at the $2^{\text{nd}}$ carbon atom differentiates $RNA$ and $DNA$.

(B) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar. Adenosine is formed when the nitrogenous base adenine is linked to the sugar ribose. Therefore,adenosine is a nucleoside.

(C) $RNA$ (Ribonucleic acid) contains a pentose sugar known as Ribose.
Deoxyribose is the pentose sugar found in $DNA$ (Deoxyribonucleic acid).

(B) Ribozymes are $RNA$ molecules that possess catalytic activity and behave like enzymes.
Unlike most enzymes which are proteins,ribozymes are composed of ribonucleic acids.

(A) Nucleic acids,such as $DNA$,primarily exhibit a secondary structure.
This is characterized by the double helical model proposed by Watson and Crick,where two polynucleotide chains are coiled around a common axis.
While some complex RNAs can fold into tertiary structures,the fundamental structural classification for nucleic acids in the context of biomolecules is the secondary structure.

(D) Nucleic acids ($DNA$ and $RNA$) are macromolecules and polymers of nucleotides.
Each nucleotide consists of three main components: a nitrogenous base,a pentose sugar,and a phosphate group.
The nitrogenous base contains carbon,hydrogen,nitrogen,and oxygen.
The pentose sugar contains carbon,hydrogen,and oxygen.
The phosphate group contains phosphorus and oxygen.
Therefore,the elements present in nucleic acid macromolecules are carbon $(C)$,hydrogen $(H)$,oxygen $(O)$,nitrogen $(N)$,and phosphorus $(P)$.

(C) nucleoside is composed of a sugar molecule and a heterocyclic base.
In contrast,a nucleotide is composed of three components: a sugar molecule,a phosphate group,and a heterocyclic base.

(A) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar.
Cytidine is formed when the nitrogenous base Cytosine $(C)$ combines with a pentose sugar $(S)$.
Since it consists only of a nitrogenous base and a sugar,it is classified as a nucleoside.
Therefore,the correct option is $A$.

(A) $Nucleoside$ 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 correct relationship is: $Nucleoside + Phosphate = Nucleotide$.

(B) nucleoside is formed by the combination of a nitrogenous base and a pentose sugar.
Adenosine,guanosine,uridine,and cytidine are formed by the combination of nitrogenous bases (adenine,guanine,uracil,and cytosine,respectively) with ribose sugar.
Since these contain ribose sugar,they are the nucleosides of $RNA$.
In $DNA$,the corresponding nucleosides are deoxyadenosine,deoxyguanosine,deoxythymidine,and deoxycytidine.

(A) nucleotide is composed of a nitrogenous base,a pentose sugar,and a phosphate group.
When a nitrogenous base is linked to a pentose sugar,it forms a nucleoside.
When a phosphate group is added to a nucleoside,it forms a nucleotide.
Adenylic acid,uridylic acid,guanylic acid,and cytidylic acid are the phosphorylated forms of adenosine,uridine,guanosine,and cytidine,respectively.
These are the constituent nucleotides of $RNA$ (Ribonucleic acid),as they contain the sugar ribose and the base uracil instead of thymine.

(B) The given structure shows a nitrogenous base (Adenine) attached to a pentose sugar,which has a hydroxyl $(-OH)$ group at the $2'$ position.
This indicates that the sugar is ribose,making the molecule a ribonucleotide.
$A$ nucleotide consisting of adenine,ribose sugar,and a phosphate group is called adenylic acid (or adenosine monophosphate).
Since it contains ribose sugar,it is a component of $RNA$.

(B) The structure of $DNA$ is famously described as a double helix,which represents its secondary structure.
In the context of biological macromolecules,the primary structure refers to the sequence of nucleotides.
The secondary structure refers to the spatial arrangement of the polynucleotide chain,such as the double-helical structure of $DNA$ stabilized by hydrogen bonding between complementary base pairs.
Therefore,$DNA$ is typically displayed and studied at the secondary level.

(B) Genetic material,such as $DNA$ and $RNA$,consists of nucleotides.
Each nucleotide is composed of a nitrogenous base,a pentose sugar,and a phosphate group.
Phosphorus is a key element in the phosphate backbone of these nucleic acids.
Therefore,phosphorus is an essential structural component of genetic material.

(B) The provided chemical structure shows a nicotinamide adenine dinucleotide phosphate $(NADP^+)$ molecule.
It consists of two nucleotides joined by a phosphate group.
One nucleotide contains a nicotinamide ring,and the other contains an adenine base.
Crucially,there is an additional phosphate group attached to the $2'$ carbon of the ribose sugar associated with the adenine base,which distinguishes $NADP^+$ from $NAD^+$.
Therefore,the correct structure is $NADP$.

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

(D) $Nucleotide$ is composed of three components: a nitrogenous base, a pentose sugar, and a phosphate group.
When the phosphate group is removed from a $Nucleotide$, the remaining structure is called a $Nucleoside$.
Therefore, the relationship is defined as: $Nucleoside = Nucleotide - \text{Phosphate group}$.