Translation Questions in English

(C) Enzymes are biological catalysts that are primarily composed of proteins. The process of protein synthesis,where the genetic information stored in $mRNA$ is decoded to form a polypeptide chain (protein) on ribosomes,is known as $Translation$. Therefore,the synthesis of enzymes occurs through the process of $Translation$.

(D) $tRNA$ (transfer $RNA$) is known as the smallest $RNA$ molecule,consisting of approximately $73-93$ nucleotides.
It functions as an adapter molecule that carries specific amino acids to the ribosome during protein synthesis.
Its secondary structure is often represented as a clover leaf-like structure.
Option $(d)$ is incorrect because $rRNA$ (ribosomal $RNA$) is the largest of the $RNAs$ found in the cell,not $tRNA$.

(D) Option $A$ is incorrect because $t-RNA$ carries amino acids,not $r-RNA$.
Option $B$ is incorrect because transcription is the synthesis of $RNA$ from $DNA$,not protein synthesis.
Option $C$ is incorrect because the process described is transcription,not translation.
Option $D$ is correct because an anticodon is a sequence of three nucleotides on a $t-RNA$ molecule that is complementary to a specific codon on an $m-RNA$ molecule,allowing them to bind through hydrogen bonding.

(C) The correct sequence for protein synthesis is as follows:
$1$. Structural gene: The segment of $DNA$ that acts as a template.
$4$. Transcription: The process of synthesizing $mRNA$ from the structural gene.
$2$. Messenger $RNA$ $(mRNA)$: The transcript formed after transcription.
$3$. Ribosomes: The cellular machinery that binds to $mRNA$ to facilitate protein synthesis.
$5$. Translation: The process where ribosomes read the $mRNA$ sequence to synthesize a polypeptide chain.
Therefore,the correct sequence is $1, 4, 2, 3, 5$.

(B) The $t-RNA$ molecule contains an anticodon loop that possesses a sequence of three nitrogenous bases complementary to the codon present on the $m-RNA$ molecule.
During the process of translation,the anticodon of the $t-RNA$ forms hydrogen bonds with the codon of the $m-RNA$ to ensure the correct amino acid is added to the growing polypeptide chain.

(C) The amino acid binding site is located at the $3'$ end of the $tRNA$ molecule.
This site consists of a $CCA$ sequence where the amino acid is covalently attached.
Therefore,the amino acid binding site and the anticodon loop are the two primary functional recognition sites of $tRNA$.

(B) The enzyme aminoacyl-tRNA synthetase plays a crucial role in protein synthesis by catalyzing the attachment of a specific amino acid to its corresponding $tRNA$ molecule.
This process is known as the 'charging' of $tRNA$ or aminoacylation of $tRNA$.
Once the $tRNA$ is charged with its specific amino acid,it can participate in the translation process at the ribosome.
Therefore,the correct function of this enzyme is charging $tRNA$ molecules.

(A) The $tRNA$ (transfer $RNA$) acts as an adapter molecule.
It has many varieties,where each variety is specific for a particular amino acid.
During protein synthesis,$tRNA$ picks up its specific amino acid from the amino acid pool in the cytoplasm and transports it to the $mRNA$ template on the ribosomes.
This process ensures that the amino acids are added in the correct sequence as specified by the genetic code.

(D) $tRNA$ (transfer $RNA$) acts as an adapter molecule during protein synthesis. Its primary function is to carry specific amino acids to the ribosome and place them in the correct sequence based on the codon present on the $mRNA$ template. Therefore,it is responsible for the selection and transport of amino acids.

(D) . An 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 $RNA$ $(mRNA)$. It is the site on the $tRNA$ molecule that recognizes and binds to the specific codon on the $mRNA$ during protein synthesis.

(D) An anticodon is a sequence of three nucleotides (a triplet) located on the $tRNA$ molecule.
It is complementary to the codon on the $mRNA$ strand.
These three bases are located on an exposed loop of the $tRNA$ molecule,known as the anticodon loop,which allows them to base-pair with the corresponding codon during the process of translation.

(D) The process of protein synthesis from the information present in $m-RNA$ is known as translation. During this process,the genetic code on $m-RNA$ is decoded to assemble amino acids into a polypeptide chain.

(D) Genes regulate the growth and differentiation of an organism by controlling the processes of transcription and translation. Transcription is the process of synthesizing $mRNA$ from $DNA$,and translation is the process of synthesizing proteins from $mRNA$. These proteins act as enzymes,structural components,or signaling molecules that drive cellular growth and differentiation.

(B) Protein synthesis is a process where the genetic information stored in $mRNA$ is translated into a polypeptide chain.
During translation,$mRNA$ acts as a template.
The sequence of nucleotides (codons) on the $mRNA$ determines the sequence of amino acids in the protein.
This process is mediated by $tRNA$ molecules,which carry specific amino acids.
Each $tRNA$ has an anticodon that base-pairs with the complementary codon on the $mRNA$.
Therefore,the $mRNA$ base sequence dictates the order in which amino acid-charged $tRNA$ molecules align,thereby defining the primary structure of the protein.

(B) In eukaryotic protein synthesis,the process of translation always begins with the amino acid $Methionine$.
This is because the start codon,$AUG$,codes for $Methionine$.
Therefore,the polypeptide chain must start with $Methionine$ at the $N$-terminal position.
Among the given options,only option $B$ starts with $Methionine$.

(B) In the process of protein synthesis,the first step is the activation of amino acids. During this step,the specific amino acid (in this case,glycine) is attached to its corresponding $tRNA$ molecule to form aminoacyl-$tRNA$. Since this is the initial step where the amino acid is incorporated into the translation machinery,the radioactivity from the labeled glycine will first be detected in the $tRNA$ fraction.

(B) The arrangement of ribosomes in chains along an $mRNA$ molecule is known as a polysome or polyribosome.
This arrangement allows for the simultaneous translation of a single $mRNA$ molecule by multiple ribosomes.
Consequently,many copies of the same polypeptide chain can be synthesized from a single $mRNA$ molecule at the same time.
This significantly increases the efficiency and rate of protein synthesis compared to a situation where ribosomes occur singly.

(B) $tRNA$ (transfer $RNA$) acts as an adapter molecule. Its primary function is to carry specific amino acids from the cytoplasm to the ribosome during the process of protein synthesis (translation). The $tRNA$ molecule has an amino acid attachment site at its $3'$ end,which binds to the specific amino acid,and an anticodon loop that recognizes the codon on the $mRNA$.

(C) The correct answer is $C$.
$1$. Amino acid activation requires $ATP$ to form aminoacyl-$AMP$ complex.
$2$. Aminoacyl $tRNA$ binding to the $A$-site requires $GTP$ hydrolysis.
$3$. Translocation requires $GTP$ hydrolysis to shift the ribosome along the $m-RNA$.
$4$. The peptidyl transferase reaction is a ribozyme-catalyzed reaction that forms a peptide bond between the amino acid at the $A$-site and the polypeptide chain at the $P$-site. This reaction does not require the hydrolysis of $ATP$ or $GTP$ as the energy is derived from the high-energy ester bond between the amino acid and the $tRNA$.

(B) The process of protein synthesis (translation) involves three main steps: $1$. Initiation,$2$. Elongation,and $3$. Termination. Transcription is the process of synthesizing $RNA$ from a $DNA$ template,which occurs before protein synthesis. Therefore,transcription is not a step in the polymerization of amino acids during protein synthesis.

(D) $DNA$ acts as the template for the transcription of all types of $RNA$ molecules ($mRNA$,$rRNA$,and $tRNA$).
However,$DNA$ does not directly participate in the synthesis of proteins.
Protein synthesis occurs at the ribosomes,where the genetic information carried by $mRNA$ is translated into a polypeptide chain through the action of $tRNA$ and $rRNA$.

(D) The correct answer is $(d)$. Translation is the process of protein synthesis which occurs in the cytoplasm of both prokaryotes and eukaryotes. In eukaryotes,transcription occurs in the nucleus,but translation takes place in the cytoplasm. Therefore,the statement that translation occurs in the nucleus is incorrect. Additionally,translation is not based on the operon model; the operon model describes the regulation of gene expression in prokaryotes.

(B) The anticodon is a sequence of three nucleotides forming a unit of genetic code in a transfer $RNA$ $(t-RNA)$ molecule,corresponding to a complementary codon in messenger $RNA$ $(m-RNA)$.
During the process of translation,the anticodon of the $t-RNA$ base-pairs with the codon on the $m-RNA$ to ensure the correct amino acid is added to the growing polypeptide chain.

(A) In eukaryotic protein synthesis,the process of translation begins with the initiation codon $AUG$.
This codon codes for the amino acid Methionine.
Therefore,the initiation of the polypeptide chain is induced by Methionine.

(A) Streptomycin is an aminoglycoside antibiotic that binds to the $30S$ ribosomal subunit of prokaryotic ribosomes.
This binding interferes with the initiation of protein synthesis and causes misreading of the genetic code.
Therefore,streptomycin specifically inhibits prokaryotic translation.

(B) In the process of protein synthesis (translation),the genetic information stored in the $DNA$ is transcribed into $mRNA$.
$mRNA$ acts as a template that carries the genetic code in the form of codons.
Each codon consists of a sequence of three nucleotides that specifies a particular amino acid.
$tRNA$ acts as an adapter molecule that brings the specific amino acid to the ribosome based on the codon sequence on the $mRNA$.
Therefore,the sequence of amino acids in a polypeptide chain is directly determined by the sequence of nucleotides in the $mRNA$.

(B) During the process of protein synthesis (translation),the $m-RNA$ molecule binds to the ribosome. The ribosome acts as the site for protein synthesis,where it reads the genetic code on the $m-RNA$ and facilitates the assembly of amino acids into a polypeptide chain.

(C) The process of genetic information flow from $DNA$ to $RNA$ is called $Transcription$.
The process of converting the genetic information from a polymer of nucleotides (mRNA) to a polymer of amino acids (polypeptide chain) is known as $Translation$.
$Replication$ is the process of making a copy of $DNA$.
$Reverse \text{ } transcription$ is the synthesis of $DNA$ from an $RNA$ template.
Therefore, the correct answer is $Translation$.

(D) Translation is the process of protein synthesis where the genetic information stored in $mRNA$ (messenger $RNA$) is decoded to form a polypeptide chain.
$1$. The $mRNA$ acts as a template that carries the sequence of codons.
$2$. Ribosomes and $tRNA$ molecules facilitate the assembly of amino acids in the correct order based on the $mRNA$ sequence.
$3$. Thus,the correct definition is that protein is synthesized from an $RNA$ message.

(C) Statement $i$ is correct: $t-RNA$ contains an anticodon loop with bases complementary to the $mRNA$ codon.
Statement $ii$ is correct: The $3'$ end of $t-RNA$ binds to a specific amino acid.
Statement $iii$ is correct: Each $t-RNA$ is specific for a particular amino acid.
Statement $iv$ is correct: There is an initiator $t-RNA$ that carries methionine (in eukaryotes) or formyl-methionine (in prokaryotes) to start translation.
Statement $v$ is incorrect: There is no $t-RNA$ for termination (stop codons). Termination is mediated by release factors that recognize stop codons $(UAA, UAG, UGA)$.
Therefore,statements $i, ii, iii,$ and $iv$ are correct.

(B) According to the 'one gene-one polypeptide' hypothesis,a single gene contains the genetic information required to code for the synthesis of a single specific polypeptide chain. While some genes code for functional $RNA$ molecules (like $rRNA$ or $tRNA$),in the context of protein synthesis,the fundamental unit of genetic expression is the polypeptide.

(C) The $t-RNA$ (transfer $RNA$) molecule acts as an adapter molecule during protein synthesis.
It contains a specific sequence of three nitrogenous bases at one end,which is complementary to the codon present on the $m-RNA$ (messenger $RNA$) strand.
This specific sequence of three bases on the $t-RNA$ is called an $Anticodon$.
During translation,the $Anticodon$ of the $t-RNA$ base-pairs with the corresponding $Codon$ on the $m-RNA$ to ensure the correct amino acid is incorporated into the growing polypeptide chain.

(B) The $t-RNA$ (transfer $RNA$) molecule contains a specific sequence of three nucleotides known as the anticodon.
This anticodon is complementary to the codon present on the $m-RNA$ (messenger $RNA$) strand.
During the process of translation,the anticodon of $t-RNA$ base-pairs with the corresponding codon on $m-RNA$ to ensure that the correct amino acid is added to the growing polypeptide chain.

(C) $1$. The template strand of $DNA$ is $3'-AAA-AGT-GAC-TAG-TGA-5'$.
$2$. During transcription,$mRNA$ is synthesized complementary to the template strand in the $5' \rightarrow 3'$ direction.
$3$. The $mRNA$ sequence will be $5'-UUU-UCA-CUG-AUC-ACU-3'$.
$4$. The codons on $mRNA$ are: $1^{st}: UUU, 2^{nd}: UCA, 3^{rd}: CUG, 4^{th}: AUC, 5^{th}: ACU$.
$5$. The third codon is $CUG$.
$6$. The anticodon on $tRNA$ is complementary to the $mRNA$ codon. For $CUG$,the complementary anticodon is $GAC$.

(C) The codon $UAA$ is a stop codon (nonsense codon).
When the $25^{th}$ codon mutates to $UAA$,the translation process terminates prematurely at the $24^{th}$ amino acid.
Therefore,the ribosome will release the polypeptide chain after the $24^{th}$ amino acid is incorporated.
As a result,a polypeptide chain consisting of only $24$ amino acids will be formed.

(D) To determine the number of amino acids,we must identify the open reading frame starting from the start codon $(AUG)$ and ending at the first stop codon.
$1$. The sequence is $5'-AUG\ CUA\ UAC\ UAA\ CUG\ CCA\ UGC\ UAG-3'$.
$2$. The start codon is $AUG$,which codes for Methionine.
$3$. The codons are read in triplets: $AUG$ (Met),$CUA$ (Leu),$UAC$ (Tyr),$UAA$ (Stop).
$4$. The codon $UAA$ is a stop codon (nonsense codon),which signals the termination of protein synthesis.
$5$. Therefore,the translation stops at $UAA$,and the amino acids incorporated are Methionine,Leucine,and Tyrosine.
$6$. The total number of amino acids in the polypeptide chain is $3$.

(B) During the process of translation (protein synthesis),the ribosome has two main sites for tRNA binding: the $'P'$ (peptidyl) site and the $'A'$ (aminoacyl) site.
$1$. The growing polypeptide chain is attached to the tRNA present at the $'P'$ site.
$2$. $A$ new amino acid is brought to the $'A'$ site by its respective tRNA.
$3$. $A$ peptide bond is formed between the carboxyl group $(-COOH)$ of the amino acid (or polypeptide chain) attached to the tRNA at the $'P'$ site and the amino group $(-NH_2)$ of the amino acid attached to the tRNA at the $'A'$ site.
$4$. This reaction is catalyzed by the enzyme peptidyl transferase (a ribozyme).

(D) Translation is the process of protein synthesis in which the genetic information present in $mRNA$ is translated into a sequence of amino acids. During this process,the ribosome facilitates the polymerization of amino acids to form a polypeptide chain. Therefore,translation involves the polymerization of amino acids.

(A) The $t-RNA$ molecule has an amino acid acceptor end,which is the $3'$ end of the molecule. This end contains the conserved sequence $CCA$ where the specific amino acid is attached via an ester bond. This process is known as aminoacylation or charging of $t-RNA$.

(C) The $t-RNA$ (transfer $RNA$) is known as an adapter molecule.
It acts as an adapter because it has an anticodon loop that recognizes and binds to the specific codon on the $m-RNA$ template,and at the same time,it carries the corresponding amino acid at its $3'$ end.
This dual function allows it to bridge the gap between the genetic code in $m-RNA$ and the amino acid sequence in a polypeptide chain.

(C) Translation is the process of protein synthesis from $mRNA$.
$1$. It initiates at the start codon $AUG$.
$2$. It terminates when the ribosome reaches a stop codon $(UAA, UAG, UGA)$.
$3$. Translation occurs in the cytoplasm (or on the rough endoplasmic reticulum in eukaryotes) where ribosomes are present.
$4$. The operon model describes the regulation of gene expression in prokaryotes,not the mechanism of translation itself. Therefore,the statement that translation is based on the operon model is incorrect.

(C) During the process of translation,$r-RNA$ (ribosomal $RNA$) performs two critical functions:
$1$. Structural role: It acts as a structural component of the ribosome,providing the scaffold for protein synthesis.
$2$. Catalytic role: The $23S$ $r-RNA$ in bacteria acts as a ribozyme (peptidyl transferase),which catalyzes the formation of peptide bonds between amino acids.
Therefore,$r-RNA$ is the correct answer.

(A) Streptomycin is an aminoglycoside antibiotic produced by the bacterium $Streptomyces$ $griseus$.
It acts by binding to the $30S$ ribosomal subunit of the prokaryotic ribosome.
This binding interferes with the initiation of protein synthesis and causes misreading of the genetic code during the translation process.
Therefore, it specifically inhibits prokaryotic translation.

(D) To incorporate one amino acid into a polypeptide chain during translation,the cell requires $1$ $ATP$ molecule for the activation of the amino acid (aminoacyl-tRNA synthetase reaction) and $2$ $GTP$ molecules (one for the binding of aminoacyl-tRNA to the $A$-site and one for translocation).
Therefore,for $n$ amino acids,the requirement is $n$ $ATP$ and $2n$ $GTP$ molecules.
For $25$ amino acids:
$ATP$ required = $25 \times 1 = 25$
$GTP$ required = $25 \times 2 = 50$
Thus,the correct answer is $25\ ATP$ and $50\ GTP$.

(D) Tetracycline is a broad-spectrum antibiotic that functions by inhibiting protein synthesis in bacteria.
It specifically binds to the $30S$ ribosomal subunit of the bacterial ribosome.
By binding to this site,it prevents the attachment of aminoacyl-$tRNA$ to the $A$-site (acceptor site) of the $mRNA$-$ribosome$ complex.
This blockage prevents the elongation of the polypeptide chain,thereby inhibiting protein synthesis.

(D) In prokaryotic translation initiation,the process involves several steps.
$1$. The $30S$ ribosomal subunit binds to the $mRNA$.
$2$. The initiator $tRNA$ (fMet-$tRNA$) binds to the start codon on the $mRNA$ with the help of initiation factors $(IF1, IF2, IF3)$.
$3$. $GTP$ is specifically required for the binding of the $50S$ ribosomal subunit to the $30S$ initiation complex to form the complete $70S$ ribosome.
Therefore,the correct option is $D$.

(C) In bacteria (prokaryotes),the $AUG$ codon acts as the initiator codon. During the process of translation,the first amino acid incorporated into the polypeptide chain is $N$-formyl methionine. While $AUG$ codes for methionine in eukaryotes,in prokaryotes,it specifically codes for $N$-formyl methionine at the start of the protein synthesis process.

(D) The expression of genes,which governs growth and differentiation in organisms,is primarily regulated through the processes of transcription and translation.
Transcription is the process where $DNA$ is copied into mRNA,and translation is the process where mRNA is decoded to synthesize specific proteins.
These proteins then perform various functions,including the regulation of growth and cellular differentiation.

(A) When several ribosomes attach to a single $mRNA$ molecule to form a chain,this structure is called a $polysome$ or $polyribosome$.
This structure allows for the simultaneous translation of a single $mRNA$ strand into multiple copies of the same polypeptide chain,thereby increasing the efficiency of protein synthesis.
$Informosomes$ are complexes of $mRNA$ and proteins found in the cytoplasm,which are distinct from the translation machinery involving ribosomes.