Translation Questions in English

(A) During the process of translation,multiple ribosomes can attach to a single $mRNA$ molecule to synthesize several copies of the same polypeptide simultaneously. This structure is known as a polysome or polyribosome. This mechanism allows for the efficient translation of $mRNA$ into proteins.

(B) During the process of translation,multiple ribosomes can attach to a single $mRNA$ molecule to synthesize multiple copies of the same polypeptide chain simultaneously.
This complex structure,consisting of an $mRNA$ strand and several ribosomes attached to it,is known as a polysome or polyribosome.
This mechanism allows for the efficient translation of genetic information into proteins.

(A) The primary structure of a protein is defined by the linear sequence of amino acids in the polypeptide chain.
This sequence is determined by the genetic information stored in the $DNA$ of the cell.
Genes are segments of $DNA$ that provide the instructions for the synthesis of specific proteins.
Therefore,the process of forming the primary structure of a protein is controlled by genes.

(C) The $tRNA$ molecule contains an anticodon loop,which consists of a sequence of $3$ nitrogenous bases (nucleotides) that are complementary to the specific codon on the $mRNA$ strand.
These $3$ nucleotides are collectively known as the anticodon.
Therefore,the correct answer is $3$.

(C) $t-RNA$ (transfer $RNA$) molecule is a small $RNA$ molecule that plays a crucial role in protein synthesis.
It typically consists of a single strand of $RNA$ folded into a specific cloverleaf structure.
The length of a $t-RNA$ molecule generally ranges between $73$ and $93$ nucleotides.
Among the given options,$75$ is the most accurate representative value for the length of a $t-RNA$ molecule.

(B) $t-RNA$ (transfer $RNA$) acts as an adapter molecule. It contains an anticodon loop that has bases complementary to the code on $m-RNA$. During the process of translation,the anticodon of $t-RNA$ pairs with the corresponding codon on $m-RNA$ to ensure the correct amino acid is brought to the ribosome.

(A) The $t-RNA$ (transfer $RNA$) acts as an adapter molecule during the process of translation.
It has an anticodon loop that recognizes the codon on the $m-RNA$ and a specific binding site for an amino acid at its $3'$ end.
It picks up specific amino acids from the cytoplasm and brings them to the ribosome,where they are arranged in the sequence specified by the $m-RNA$ to form a polypeptide chain.

(B) The process of protein synthesis involves the transcription of genetic information from $DNA$ to $m-RNA$.
$m-RNA$ (messenger $RNA$) acts as a template that carries the genetic code from the nucleus to the ribosomes in the cytoplasm.
At the ribosomes,this code is translated into a specific sequence of amino acids to form a polypeptide chain,which constitutes a specific protein.
While enzymes are proteins,the primary function of $m-RNA$ is the synthesis of proteins in general,making $B$ the most accurate and comprehensive answer.

(D) After the process of translation is completed,the $m-RNA$ molecule is no longer required for protein synthesis.
In eukaryotic cells,the $m-RNA$ is degraded by ribonucleases in the cytoplasm.
This degradation process is essential for regulating gene expression and recycling the nucleotides for future transcription processes.

(A) An anticodon is a sequence of three nucleotides located on a $tRNA$ molecule.
This sequence forms complementary base pairs with a specific codon present on the $mRNA$ during the process of translation.
Therefore,an anticodon consists of three nucleotides.

(B) The primary function of $t-RNA$ (transfer $RNA$) in protein synthesis is to act as an adapter molecule.
During the process of translation,$t-RNA$ reads the genetic code present on the $m-RNA$ template.
It carries the specific amino acid corresponding to the codon on the $m-RNA$ from the cytoplasm to the ribosome,where the polypeptide chain is synthesized.
Therefore,$t-RNA$ acts as a bridge between the mRNA sequence and the amino acid sequence.

(B) The primary function of transfer $RNA$ $(tRNA)$ is to act as an adapter molecule during protein synthesis.
It recognizes specific amino acids and transports them to the ribosome.
It contains an anticodon that base-pairs with the complementary codon on the $mRNA$ strand,ensuring that the correct amino acid is added to the growing polypeptide chain.

(D) Protein synthesis (translation) involves the participation of three main types of $RNA$: $m-RNA$ (messenger $RNA$),$t-RNA$ (transfer $RNA$),and $r-RNA$ (ribosomal $RNA$).
$m-RNA$ carries the genetic code from $DNA$.
$t-RNA$ brings specific amino acids to the ribosome.
$r-RNA$ forms the structural and catalytic core of the ribosome.
$FAD$ (Flavin Adenine Dinucleotide) is a coenzyme involved in redox reactions in metabolism,such as the Krebs cycle,and is not a component of the protein synthesis machinery.

(D) The correct answer is $D$.
In a bacterial cell (prokaryote),the $70S$ ribosome consists of a large $50S$ subunit and a small $30S$ subunit.
The $50S$ subunit contains the $23S\ rRNA$,which functions as a ribozyme.
$A$ ribozyme is an $RNA$ molecule that possesses catalytic activity.
Specifically,the $23S\ rRNA$ catalyzes the formation of peptide bonds between amino acids during protein synthesis,a process known as peptidyl transferase activity.
In contrast,$snRNA$ and $hnRNA$ are primarily found in eukaryotic cells,and $5S\ rRNA$ is a structural component of the ribosome.

(C) The correct answer is $C$.
In bacteria,the $23S\ rRNA$ is a component of the large ribosomal subunit $(50S)$.
It functions as a structural component of the ribosome and also acts as a ribozyme (specifically,it possesses peptidyl transferase activity) which catalyzes the formation of peptide bonds between amino acids during protein synthesis.

(C) During the process of translation,multiple ribosomes can attach to a single $mRNA$ molecule to synthesize multiple copies of the same polypeptide chain simultaneously. This structure,consisting of a single $mRNA$ strand with several ribosomes attached to it,is called a polyribosome or polysome.

(C) Neomycin is a broad-spectrum antibiotic that was first isolated from a strain of $Streptomyces \, fradiae$.
It is effective against both Gram-positive and Gram-negative bacteria.
Its mechanism of action involves the selective inhibition of protein synthesis on the $70S$ (prokaryotic) ribosome.
Specifically, it inhibits the interaction between $mRNA$ and $tRNA$ during the translation process, thereby preventing the formation of the polypeptide chain.

(C) The correct answer is $C$.
$mRNA$ (messenger $RNA$) carries the genetic information from $DNA$ to the ribosomes,where protein synthesis occurs.
The sequence of nucleotides in $mRNA$ is organized into triplets called codons,each of which specifies a particular amino acid.
During translation,$tRNA$ molecules with complementary anticodons bring the corresponding amino acids to the $mRNA$ template,ensuring that the amino acids are linked in the order dictated by the $mRNA$ sequence.
$rRNA$ forms the structural and catalytic core of ribosomes,while $cDNA$ is complementary $DNA$ synthesized from an $RNA$ template,which is not directly involved in the translation process of protein synthesis.

(C) $t-RNA$ (transfer $RNA$) acts as an adapter molecule.
It possesses an anticodon loop that is complementary to the codon on $mRNA$.
It has an amino acid acceptor end (at the $3'$ end) to which a specific amino acid binds.
$t-RNAs$ are highly specific for each amino acid; there is at least one specific $t-RNA$ for each amino acid.
There are no $t-RNAs$ for stop codons ($UAA$,$UAG$,$UGA$),which is why they act as termination signals.
Therefore,the statement that '$t-RNAs$ are not specific for each amino acid' is incorrect.

(C) In eukaryotic organisms,the initiation of protein synthesis begins with the amino acid $Methionine$.
Unlike prokaryotes,where the initiator $tRNA$ carries $N-formylmethionine$,eukaryotes use a specific initiator $tRNA$ that carries $Methionine$ $(Met-tRNA_i^{Met})$ to the $AUG$ start codon.
Therefore,the correct molecule carried by $tRNA$ during initiation in eukaryotes is $Methionine$.

(A) In bacteria,the process of translation involves the formation of peptide bonds between amino acids.
This reaction is catalyzed by the $23S \, rRNA$,which is a component of the $50S$ large ribosomal subunit.
Because this $rRNA$ molecule possesses catalytic activity,it is referred to as a ribozyme.
Therefore,$23S \, rRNA$ acts as an enzyme in bacteria.

(C) In a bacterial cell,the $23S$ $rRNA$ acts as a ribozyme,which is an $RNA$ molecule that functions as a biological catalyst.
Specifically,it is responsible for the peptidyl transferase activity during protein synthesis,which catalyzes the formation of peptide bonds between amino acids in the ribosome.

(B) Translation is the process in which the genetic information present in $mRNA$ is used to synthesize a polypeptide chain (protein).
This process occurs in the cytoplasm on ribosomes,where $tRNA$ molecules bring specific amino acids based on the codon sequence of the $mRNA$.
Therefore,translation is essentially the process of protein synthesis.

(A) Protein synthesis,also known as translation,involves three main stages: $Initiation$,$Elongation$,and $Termination$.
Transcription is the process of synthesizing $RNA$ from a $DNA$ template,which occurs in the nucleus before translation.
Therefore,transcription is not a stage of protein synthesis itself,but rather a precursor process.

(C) The anticodon is a sequence of three nucleotides forming a unit of genetic code in a transfer $RNA$ $(tRNA)$ molecule,corresponding to a complementary codon in messenger $RNA$ $(mRNA)$.
During protein synthesis,the anticodon of $tRNA$ base-pairs with the codon of $mRNA$ to ensure the correct amino acid is added to the polypeptide chain.
Therefore,the anticodon is present on $tRNA$.

(B) The $t-RNA$ (transfer $RNA$) acts as an adapter molecule during protein synthesis.
It has an anticodon loop that recognizes the codon on $m-RNA$ and a $3'$ end that carries the specific amino acid corresponding to that codon.
Thus,it picks up amino acids from the cytoplasm and transports them to the ribosome for polypeptide chain assembly.

(A) In eukaryotic genes,the coding sequences are known as exons,while the non-coding sequences are known as introns.
During the process of transcription,both exons and introns are transcribed into $pre-mRNA$.
Subsequently,through the process of splicing,the introns are removed,and the exons are joined together to form mature $mRNA$.
The mature $mRNA$ contains the genetic information that is translated into a polypeptide chain,which folds to form a functional protein.

(B) In prokaryotic translation initiation,the formation of the initiation complex involves several steps.
$1$. The $30S$ ribosomal subunit binds to the $m-RNA$.
$2$. The initiator $t-RNA$ (formyl-methionyl $t-RNA$) binds to the start codon.
$3$. The association of the $50S$ ribosomal subunit with the $30S$ initiation complex requires energy,which is provided by the hydrolysis of a $GTP$ molecule.
Therefore,the $GTP$ molecule is specifically required for the association of the $50S$ ribosomal subunit with the initiation complex.

(C) In bacteria,the $23S \, rRNA$ is a component of the $50S$ large ribosomal subunit. It acts as a structural $RNA$ and also functions as a ribozyme (specifically,it possesses peptidyl transferase activity) which catalyzes the formation of peptide bonds between amino acids during protein synthesis. Therefore,the correct option is $C$.

(A) The secondary structure of $tRNA$ is often depicted as a cloverleaf model. However,in its actual $3D$ conformation,the $tRNA$ molecule folds into a compact $L$-shaped structure. This $3D$ shape is essential for its function in protein synthesis,allowing it to interact with both the ribosome and the $mRNA$ template.

(D) The Assertion is incorrect because $mRNA$ attaches to the ribosome at the $5'$ end,specifically at the Shine-Dalgarno sequence in prokaryotes or the $5'$ cap in eukaryotes,not the $3'$ end.
The Reason is also incorrect as there is no such thing as an '$F-$ capsular nucleotide' in $mRNA$ structure.
Therefore,both the Assertion and the Reason are incorrect.

(A) $DNA$ replication and transcription occur inside the nucleus in eukaryotic cells. After transcription,the $mRNA$ is processed and exported from the nucleus into the cytoplasm. In the cytoplasm,the $mRNA$ binds to ribosomes,where translation (protein synthesis) takes place using available amino acids and $tRNA$. This flow of genetic information from $DNA$ to $RNA$ to protein is known as the Central Dogma. Since the Reason correctly explains why translation must occur in the cytoplasm (due to the presence of necessary machinery),the Assertion and Reason are both correct,and the Reason is the correct explanation.

(N/A) The important functions of ribosome during translation are as follows:
$1$. Ribosome acts as the site where protein synthesis takes place from individual amino acids. It consists of two subunits. The smaller subunit comes in contact with $mRNA$ and forms a protein-synthesizing complex,whereas the larger subunit provides binding sites for $tRNA$ and amino acids.
$2$. Ribosome acts as a catalyst for the formation of peptide bonds. For example,the $23S$ $rRNA$ in bacteria acts as a ribozyme to catalyze peptide bond formation.

(N/A) According to Francis Crick,there is a mechanism to read the genetic code and link it to amino acids.
Amino acids do not have any structural features that allow them to recognize the genetic code directly.
Crick postulated the presence of an adapter molecule that could read the genetic code on one side and bind to specific amino acids on the other.
$t-RNA$ (formerly known as $s-RNA$) acts as this adapter molecule.
$t-RNA$ has an anticodon loop that contains bases complementary to the code on $m-RNA$,and it has an amino acid acceptor end to which the specific amino acid binds.
For each amino acid,there is a specific $t-RNA$. There is another specific $t-RNA$ for initiation,called initiator $t-RNA$. There are no $t-RNA$ molecules for stop codons.
The secondary structure of $t-RNA$ is clover-leaf shaped,but in its actual three-dimensional structure,$t-RNA$ is an inverted $L$-shaped molecule.

(N/A) Translation refers to the process of polymerization of amino acids to form a polypeptide chain.
The order and sequence of amino acids are defined by the sequence of bases in the $m-RNA$.
The amino acids are joined by a peptide bond. Formation of a peptide bond requires energy. Therefore,in the first phase,amino acids are activated in the presence of $ATP$.
This process is called charging of $t-RNA$ or aminoacylation of $t-RNA$. When two such charged $t-RNA$ molecules are brought close enough,the formation of a peptide bond between them is favored. The presence of a catalyst increases the rate of peptide bond formation.
The cellular factory responsible for protein synthesis is the ribosome. It consists of structural $RNAs$ and about $80$ different proteins. In its inactive state,it exists as two subunits: a large subunit and a small subunit.
When the small subunit encounters an $m-RNA$,the process of translation of the $m-RNA$ to protein begins. The large subunit has two sites for subsequent amino acids to bind to and thus be close enough to each other for the formation of a peptide bond.
The ribosome also acts as a catalyst ($23S$ $r-RNA$ in bacteria is the enzyme-ribozyme) for the formation of the peptide bond.
$A$ translational unit in $m-RNA$ is the sequence of $RNA$ that is flanked by the start codon $(AUG)$ and the stop codon and codes for a polypeptide. An $m-RNA$ also has some additional sequences that are not translated and are referred to as untranslated regions $(UTR)$.
The $UTR$s are present at both $5'$-end (before start codon) and $3'$-end (after stop codon). They are required for efficient translation process.

(N/A) Genes are segments of $DNA$ that carry the genetic information required for the synthesis of specific proteins or enzymes.
According to the central dogma of molecular biology, the expression of a trait occurs through the following steps:
$1$. Transcription: The genetic information stored in the $DNA$ (gene) is transcribed into $mRNA$.
$2$. Translation: The $mRNA$ is then translated into a specific protein or enzyme.
$3$. Trait Expression: The synthesized protein may directly function as a structural component or trait, or the enzyme may catalyze a reaction on a specific substrate to produce a product, which ultimately manifests as a particular phenotypic trait.

(N/A) $1.$ Transfer $\text{RNA}$ $(t\text{-RNA})$: It is an adapter molecule that reads the code for protein synthesis on one end and binds to a specific amino acid on the other end.
$2.$ Ribosomal $\text{RNA}$ $(r\text{-RNA})$: It is a structural component of the ribosome. It acts as a ribozyme (catalytic $RNA$) during the process of translation.

(N/A) Translation refers to the process of polymerisation of amino acids to form a polypeptide. Ribosome is the site of protein synthesis. The amino acids are joined by a bond which is known as a peptide bond. Formation of a peptide bond requires energy. Therefore,in the first phase itself,amino acids are activated in the presence of $ATP$ and linked to their respective $tRNA$—a process commonly called activation or charging of $tRNA$,or aminoacylation of $tRNA$ to be more specific.
If two such charged $tRNAs$ are brought close enough,the formation of a peptide bond between them would be favoured energetically. The presence of a catalyst would enhance the rate of peptide bond formation. The cellular factory responsible for synthesising proteins is the ribosome. The ribosome consists of structural $RNAs$ and about $80$ different proteins. In its inactive state,it exists as two subunits: a large subunit and a small subunit.
When the small subunit encounters an $mRNA$,the process of translation of the $mRNA$ to protein begins. There are two sites in the large subunit for subsequent amino acids to bind to and thus be close enough to each other for the formation of a peptide bond. The ribosome also acts as a catalyst ($23S$ $rRNA$ in bacteria is the enzyme-ribozyme) for the formation of a peptide bond.
$A$ translational unit in $mRNA$ is the sequence of $RNA$ that is flanked by the start codon $(AUG)$ and the stop codon and codes for a polypeptide. An $mRNA$ also has some additional sequences that are not translated and are referred to as untranslated regions $(UTR)$. The $UTRs$ are present at both $5^{\prime}$-end (before start codon) and at $3^{\prime}$-end (after stop codon). They are required for efficient translation process.
For initiation,the ribosome binds to the $mRNA$ at the start codon $(AUG)$ that is recognised only by the initiator $tRNA$. The ribosome proceeds to the elongation phase of protein synthesis. During this stage,complexes composed of an amino acid linked to $tRNA$ sequentially bind to the appropriate codon in $mRNA$ by forming complementary base pairs with the $tRNA$ anticodon. The ribosome moves from codon to codon along the $mRNA$.

(D) The process of translation involves the synthesis of a polypeptide chain from an $mRNA$ template. The first phase of this process is the 'charging' of $tRNA$,also known as the aminoacylation of $tRNA$. During this step,specific amino acids are linked to their cognate $tRNA$ molecules in the presence of $ATP$. This activation is essential for the subsequent steps of translation,such as the formation of peptide bonds.

(C) The process of translation involves the synthesis of a polypeptide chain from $mRNA$.
Before the actual translation begins,the $tRNA$ must be charged with its specific amino acid.
This process is known as the aminoacylation of $tRNA$ or charging of $tRNA$.
It requires the presence of specific aminoacyl-$tRNA$ synthetase enzymes and $ATP$.
Once the $tRNA$ is charged,it can participate in the translation process at the ribosome.

(N/A) The concept of an adapter molecule that could read the genetic code and bind to specific amino acids during translation was proposed by Francis Crick in $1961$.
$tRNA$ was known before the genetic code was deciphered and was initially called $sRNA$ (soluble $RNA$),but later its role as an adapter molecule was established.
Structure of $tRNA$:
$1$. The $tRNA$ has a secondary structure that resembles a clover leaf.
$2$. Its three-dimensional structure is an inverted $L$-shaped molecule.
$3$. $tRNA$ contains specific regions:
$(i)$ Anticodon loop: It contains bases complementary to the codon on $mRNA$.
$(ii)$ Amino acid acceptor end: This end binds to the specific amino acid.
$(iii)$ $T\psi C$-loop ($T$-loop): It helps in binding to the ribosome.
$(iv)$ $D$-loop: It helps in binding to aminoacyl-tRNA synthetase.
$(v)$ Variable loop: It varies in both nucleotide composition and length.
$tRNAs$ are specific for each amino acid. For initiation,there is a specific $tRNA$ referred to as the initiator $tRNA$. There are no $tRNAs$ for stop codons.

(A) Translation refers to the process of polymerization of amino acids to form a polypeptide.
The order and sequence of amino acids are defined by the sequence of bases in the $mRNA$.
The amino acids are joined by a bond known as a peptide bond.
Formation of a peptide bond requires energy.
Therefore,in the first phase,amino acids are activated in the presence of $ATP$ and linked to their cognate $tRNA$,a process commonly called charging of $tRNA$ or aminoacylation of $tRNA$.
If two such charged $tRNAs$ are brought close enough,the formation of a peptide bond between them is favored energetically.
The presence of a catalyst enhances the rate of peptide bond formation.
The cellular factory responsible for synthesizing proteins is the ribosome.
The ribosome consists of structural $RNAs$ and about $80$ different proteins.
In its inactive state,it exists as two subunits: a large subunit and a small subunit.
When the small subunit encounters an $mRNA$,the process of translation of the $mRNA$ to protein begins.
There are two sites in the large subunit for subsequent amino acids to bind,bringing them close enough for the formation of a peptide bond.
The ribosome also acts as a catalyst ($23S$ $rRNA$ in bacteria is the enzyme ribozyme) for the formation of the peptide bond.
$A$ translational unit in $mRNA$ is the sequence of $RNA$ that is flanked by the start codon $(AUG)$ and the stop codon and codes for a polypeptide.
An $mRNA$ also has some additional sequences that are not translated,referred to as untranslated regions $(UTRs)$.
The $UTRs$ are present at both $5^{\prime}$-end (before the start codon) and at $3^{\prime}$-end (after the stop codon).
They are required for an efficient translation process.
For initiation,the ribosome binds to the $mRNA$ at the start codon $(AUG)$,which is recognized only by the initiator $tRNA$.
The ribosome then proceeds to the elongation phase of protein synthesis.
During this stage,complexes composed of amino acids linked to $tRNA$ sequentially bind to the appropriate codon in $mRNA$ by forming complementary base pairs with the $tRNA$ anticodon.

(N/A) $tRNA$ acts as an adapter molecule during protein synthesis. It performs two critical functions:
$1$. It recognizes and binds to a specific activated amino acid in the cytoplasm.
$2$. It recognizes the specific codon on the $mRNA$ template via its anticodon loop to ensure the correct amino acid is placed in the polypeptide chain.
Without this dual binding,the genetic code would not be translated accurately,leading to the synthesis of incorrect proteins.

(A) The $tRNA$ (transfer $RNA$) acts as an adapter molecule.
It has an anticodon loop that contains bases complementary to the code on the $mRNA$.
During translation,the $tRNA$ reads the genetic code on the $mRNA$ by base-pairing its anticodon with the codon on the $mRNA$ and brings the corresponding amino acid to the ribosome.
Therefore,$tRNA$ is the molecule that reads the genetic code.

(C) In prokaryotes,there is no clear-cut separation between the cytosol and the nucleus because they lack a defined nucleus.
Transcription and translation take place in the same compartment.
As a result,the translation of $m-RNA$ can begin even before the $m-RNA$ is fully transcribed from the $DNA$ template.
This phenomenon is known as coupled transcription and translation.

(A) In bacteria,there is no defined nucleus,and the genetic material is not separated from the cytoplasm by a nuclear membrane.
Transcription (synthesis of $RNA$ from $DNA$) and translation (synthesis of proteins from $mRNA$) can take place simultaneously in the same compartment.
Transcription involves ribonucleotide polymerization (forming $mRNA$),and translation involves amino acid polymerization (forming polypeptide chains).
Therefore,these two processes occur concurrently in bacteria.

(C) The principle of complementarity states that bases pair specifically (e.g.,$A$ with $T$ or $U$,and $G$ with $C$).
In $DNA$ replication,the new strand is synthesized based on the complementarity of the template strand.
In transcription,$mRNA$ is synthesized based on the complementarity of the $DNA$ template strand.
In translation,the $tRNA$ anticodon pairs with the $mRNA$ codon based on complementarity.
However,the process of translation as a whole involves the decoding of $mRNA$ into a polypeptide chain,where the genetic code is read in triplets. The interaction between the ribosome,$mRNA$,and amino acids does not follow a simple base-pairing complementarity rule for the entire process,especially regarding the peptide bond formation and the non-complementary nature of the amino acid sequence to the $mRNA$ sequence itself. Thus,among the given options,translation is the process where the direct principle of base-pairing complementarity is not the defining mechanism for the entire functional output.

(B) The process of translation refers to the synthesis of proteins (polymers of amino acids) from an $mRNA$ template (a polymer of nucleotides).
During this process,the genetic information stored in the sequence of nucleotides in $mRNA$ is translated into the sequence of amino acids in a polypeptide chain.
Therefore,it involves the synthesis of amino acid polymers from nucleotide polymers.

(C) The process of $Translation$ is the polymerization of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence of bases in the $mRNA$. Thus,in the process of $Translation$,the genetic information is transferred from the $mRNA$ (nucleic acid language) to a polypeptide chain (protein language).