Ribosomes Questions in English

(D) In bacteria,multiple ribosomes often attach to a single $mRNA$ molecule to form a chain-like structure known as a polyribosome or polysome.
This structure allows for the simultaneous translation of a single $mRNA$ strand into multiple polypeptide chains,which significantly increases the efficiency of protein synthesis.
Therefore,bacterial ribosomes,when associated with $mRNA$ in this manner,are referred to as polyribosomes.

(A) Bacteria are prokaryotic organisms,which means they lack membrane-bound organelles such as the endoplasmic reticulum or a defined nucleus.
In prokaryotic cells,ribosomes are found freely suspended in the cytoplasm.
These ribosomes are of the $70S$ type,consisting of $50S$ and $30S$ subunits.

(D) The smallest cell organelle is the ribosome.
Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells.
They are composed of ribosomal $RNA$ $(rRNA)$ and proteins.
Since they lack a membrane and are very small in size compared to other organelles like mitochondria or lysosomes,they are considered the smallest cell organelles.
Option $(D)$ is the correct answer.

(D) The Rough Endoplasmic Reticulum $(RER)$ is characterized by the presence of ribosomes on its surface.
These ribosomes are attached to the membrane of the $RER$ with the help of specific proteins known as ribophorins.
Therefore,the correct option is $(D)$.

(D) Ribosomes were first observed by $George \text{ } E. \text{ } Palade$ in $1955$ using electron microscopy. Due to their discovery by him, ribosomes are also frequently referred to as $Palade \text{ } particles$. Therefore, the correct option is $(d)$.

(B) The ribosomes found in bacteria are of the $70S$ type.
According to the endosymbiotic theory,mitochondria and chloroplasts are believed to have originated from prokaryotic organisms that were engulfed by ancestral eukaryotic cells.
Therefore,these organelles contain $70S$ ribosomes,which are structurally and functionally similar to bacterial ribosomes,unlike the $80S$ ribosomes found in the cytoplasm of eukaryotic cells.
Thus,pancreatic mitochondria contain ribosomes similar to those of bacteria.

(D) The correct answer is $D$. Ribosomes are non-membranous organelles found in both prokaryotic and eukaryotic cells. They are composed of two sub-units (large and small) made of ribosomal $RNA$ $(rRNA)$ and proteins. They are not enclosed by any membrane.

(B) The $80S$ ribosome is found in eukaryotic cells. It consists of two subunits: a larger subunit of $60S$ and a smaller subunit of $40S$. The '$S$' stands for Svedberg unit,which is a measure of the sedimentation coefficient.

(A) Ribosomes are the granular structures first observed under the electron microscope as dense particles by George Palade in $1953$.
$80S$ ribosomes are characteristic of eukaryotic cells,consisting of $60S$ and $40S$ subunits.
In contrast,prokaryotic cells (such as bacteria and cyanobacteria) contain $70S$ ribosomes,which consist of $50S$ and $30S$ subunits.
Therefore,$80S$ ribosomes are found in eukaryotic cells.

(A) Ribosomes were first observed under an electron microscope as dense particles by George Palade in $1953$.
Due to their discovery by George Palade,these particles are commonly referred to as 'Palade granules' or 'Palade particles'.
They are the sites of protein synthesis in the cell.

(A) Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells.
They are composed of ribosomal $RNA$ $(rRNA)$ and proteins.
Unlike mitochondria,plastids,or the nucleus,ribosomes do not contain $DNA$ and are not enclosed by any membrane.

(D) The correct answer is $D$.
Ribosomes are known as the "protein factories of the cell" because they are the primary sites for protein synthesis.
During the process of translation, the two subunits of the ribosome attach to the $mRNA$ strand.
The $mRNA$ carries the genetic code, which the ribosome reads to assemble amino acids into polypeptide chains, effectively synthesizing proteins.

(A) Ribosomes are composed of two subunits: a larger subunit and a smaller subunit.
These subunits remain associated with each other in the presence of a specific concentration of magnesium ions $(Mg^{2+})$.
When the concentration of $Mg^{2+}$ decreases,the subunits dissociate into their individual components.
Therefore,$Mg^{2+}$ is the essential ion that regulates the association and dissociation of ribosomal subunits.

(A) Ribosomes are granular structures first observed under the electron microscope as dense particles by George Palade in $1953$. They are composed of ribonucleic acids $(RNA)$ and proteins and are not surrounded by any membrane. In eukaryotic cells,ribosomes are found in the cytoplasm,on the rough endoplasmic reticulum,and within organelles like mitochondria and chloroplasts. Among the given options,cytoplasm is the primary site where ribosomes are found.

(D) Ribosomes are known as the protein factories of the cell. They are the sites where protein synthesis occurs through the process of translation. If all ribosomes in a cell are destroyed,the cell will lose its ability to synthesize proteins,which are essential for structural integrity,enzymatic activity,and cellular signaling. Therefore,protein synthesis will stop completely.

(D) Prokaryotic ribosomes are of the $70S$ type.
They consist of two subunits: a large $50S$ subunit and a small $30S$ subunit.
These ribosomes are composed of approximately $60\%$ ribosomal $RNA$ $(rRNA)$ and $40\%$ ribosomal proteins.
Therefore,the ratio of $RNA$ to protein is approximately $60:40$,which simplifies to $3:2$ or $1.5:1$.
Since none of the provided options $(2:1, 1:1, 3:1)$ represent this ratio accurately,the correct choice is 'None of these'.

(B) Bacterial cells are prokaryotic in nature.
Prokaryotic cells lack membrane-bound organelles such as mitochondria,the Golgi complex,and the endoplasmic reticulum.
However,they possess ribosomes,which are non-membrane-bound organelles responsible for protein synthesis.
In bacteria,these are of the $70S$ type.

(C) Ribosomes are the granular structures first observed under the electron microscope as dense particles by George Palade in $1953$.
They are composed of ribonucleic acids $(RNA)$ and proteins and are not surrounded by any membrane.
The eukaryotic ribosomes are $80S$ (where '$S$' stands for the sedimentation coefficient,Svedberg's unit),while the prokaryotic ribosomes are $70S$.
Each ribosome consists of two subunits.
The $70S$ ribosome is composed of two subunits: a larger subunit of $50S$ and a smaller subunit of $30S$.

(B) $Ribosomes$ are present in both plant and animal cells.
They are responsible for protein synthesis in both cell types.
Therefore,they perform a similar function in both.

(B) Eukaryotic ribosomes are of the $80S$ type.
They are composed of two subunits: a larger subunit and a smaller subunit.
The larger subunit is $60S$ and the smaller subunit is $40S$.
Therefore,the $80S$ ribosome dissociates into $60S$ and $40S$ subunits.

(B) The correct pair is $Polyribosomes - RNA$.
$Polyribosomes$ (or $polysomes$) are a cluster of ribosomes associated with a single $mRNA$ molecule,which helps in the translation of $mRNA$ into proteins.
$Svedberg$ unit is a measure of sedimentation rate used for ribosomes,not biomembranes.
$Dictyosomes$ are the individual stacks of the $Golgi$ apparatus,whereas 'suicidal sacs' refers to $lysosomes$.
$Cisternae$ are found in the $Golgi$ apparatus and $Endoplasmic$ $Reticulum$,not in $mitochondria$.

(B) Ribosomes are small,dense,granular structures found in both prokaryotic and eukaryotic cells.
They are composed of ribosomal $RNA$ $(rRNA)$ and proteins.
The typical diameter of a ribosome ranges from $150$ $\mathring{A}$ to $250$ $\mathring{A}$,which is approximately $15-25$ $nm$.
Among the given options,the range of $100$ to $200$ $\mathring{A}$ is the most accurate representation of their size.

(D) polyribosome (or polysome) is a structure formed when several ribosomes are attached to a single $mRNA$ molecule.
These ribosomes translate the $mRNA$ into polypeptide chains simultaneously.
This process allows for the efficient synthesis of multiple copies of the same protein from a single $mRNA$ template.

(C) Ribosomes are non-membrane-bound organelles found in all living cells.
They are composed of ribosomal $RNA$ $(rRNA)$ and various proteins.
They do not contain $DNA$ as a structural component.
Therefore,the correct composition is $RNA$ and protein.

(A) Ribosomes are composed of two subunits: a larger subunit and a smaller subunit.
These subunits remain associated with each other primarily due to the presence of $Mg^{++}$ ions.
If the concentration of $Mg^{++}$ ions falls below a critical threshold,the electrostatic attraction holding the two subunits together is weakened,causing the ribosome to dissociate into its individual subunits.

(C) Ribosomes are the sites of protein synthesis.
In prokaryotic cells, such as bacteria, ribosomes are of the $70 S$ type.
Organelles like mitochondria and chloroplasts, which are believed to have originated from endosymbiotic prokaryotes, also contain $70 S$ ribosomes.
Therefore, the ribosomes found in bacteria, prokaryotes, mitochondria, and chloroplasts are of the $70 S$ type.

(D) $Polysome$ (or $Polyribosome$) is a cluster of ribosomes held together by a strand of $mRNA$ that functions as the site of protein synthesis.
Multiple ribosomes translate a single $mRNA$ molecule simultaneously,which significantly increases the efficiency of protein production.
Therefore,the $Polysome$ is considered the functional unit of protein synthesis.

(B) Ribosomes are the cellular organelles responsible for protein synthesis in all living organisms,including plants. They act as the site where amino acids are assembled into polypeptide chains based on the genetic instructions provided by $mRNA$.

(B) Bacterial cells are prokaryotic in nature.
Prokaryotic ribosomes are of the $70 S$ type.
These ribosomes consist of two subunits: a larger $50 S$ subunit and a smaller $30 S$ subunit.
The $S$ stands for Svedberg's unit (sedimentation coefficient), which is a measure of density and size.

(D) Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells.
They are composed of $RNA$ and proteins.
Since they lack a lipid bilayer membrane,they are not considered membrane-bound organelles.
In contrast,mitochondria,lysosomes,and sphaerosomes are all surrounded by a unit membrane.

(B) Mammalian mitochondria contain $55S$ ribosomes,which are distinct from the $70S$ ribosomes found in bacteria and other organelles like chloroplasts.
These $55S$ ribosomes consist of a large $39S$ subunit and a small $28S$ subunit.

(B) Ribosomes are cellular organelles that serve as the site of protein synthesis. They are primarily composed of ribosomal $RNA$ $(rRNA)$ and various proteins. Unlike other organelles,they do not contain $DNA$ or carbohydrates as their primary structural components.

(B) In prokaryotes (e.g.,$E. coli$),the $70S$ ribosome consists of a $50S$ large subunit and a $30S$ small subunit. The $50S$ large subunit contains two types of $rRNA$ molecules: $23S$ $rRNA$ and $5S$ $rRNA$.
In eukaryotes,the $80S$ ribosome consists of a $60S$ large subunit and a $40S$ small subunit. The $60S$ large subunit contains three types of $rRNA$ molecules: $28S$ $rRNA$,$5.8S$ $rRNA$,and $5S$ $rRNA$.
Since the question asks for the number of $rRNA$ molecules in the larger subunit generally,and considering the prokaryotic model as the standard reference in many contexts,the answer is two. However,given the variation,the most commonly cited answer in the context of the $50S$ subunit is two.

(B) The correct answer is $B$. Protein synthesis occurs on ribosomes. In an animal cell,ribosomes are found in the cytoplasm (either free or attached to the endoplasmic reticulum) and within the mitochondria. Mitochondria are semi-autonomous organelles that possess their own $DNA$,$RNA$,and $70S$ ribosomes,allowing them to synthesize a portion of their required proteins independently.

(D) The correct answer is $D$. Ribosomes are known as the protein factories of the cell. They are the sites where the process of translation occurs,which is the synthesis of proteins from $mRNA$ templates. If ribosomes are destroyed,the cell loses its ability to synthesize proteins,which are essential for structural,enzymatic,and regulatory functions.

(B) In cancerous cells,the protein synthesis machinery is often altered. Ribosomes in these cells frequently aggregate or fuse together to form structures known as polyribosomes (or polysomes),which are clusters of ribosomes held together by a strand of messenger $RNA$ $(mRNA)$. This allows for the rapid and efficient translation of proteins required for the uncontrolled growth and division characteristic of cancer cells.

(A) Ribosomes were first observed in animal cells by George $E$. Palade in $1955$.
He used electron microscopy to identify these dense particles and described their structure and function,for which he was later awarded the Nobel Prize.
Therefore,the correct answer is $A$.

(C) Enzymes are proteins in nature. The process of protein synthesis,which includes the synthesis of enzymes,occurs on the ribosomes. Ribosomes are the cellular organelles responsible for translating $mRNA$ into polypeptide chains,which then fold to form functional enzymes.

(C) polysome (or polyribosome) is a structure formed when several ribosomes attach to a single $m-RNA$ molecule.
This allows for the simultaneous translation of the same $m-RNA$ strand into multiple copies of the same polypeptide chain,thereby increasing the efficiency of protein synthesis.
Therefore,the correct description is that many ribosomes are attached to a single $m-RNA$.

(A) Ribosomes are the cellular organelles responsible for protein synthesis. They are composed of ribosomal $RNA$ $(rRNA)$ and proteins. They translate the genetic code from messenger $RNA$ $(mRNA)$ into a specific sequence of amino acids to form proteins. Therefore,they are often referred to as the 'protein factories' of the cell.

(C) In eukaryotic cells,the ribosomes found in the cytoplasm and attached to the rough endoplasmic reticulum are of the $80S$ type.
However,eukaryotic cells also contain organelles like mitochondria and chloroplasts,which possess their own genetic material and ribosomes.
The ribosomes found within these semi-autonomous organelles are of the $70S$ type.
Therefore,eukaryotic cells contain both $70S$ and $80S$ ribosomes.

(A) Ribosomes are complex cellular structures composed of ribosomal $RNA$ $(rRNA)$ and various ribosomal proteins.
They are the sites of protein synthesis in the cell.
Therefore,the main components of a ribosome are protein and $RNA$.

(B) Protein synthesis is a fundamental biological process that occurs in all living cells.
Ribosomes are the cellular organelles responsible for the translation of $mRNA$ into polypeptide chains,which are the building blocks of proteins.
In plant cells,as in other eukaryotic cells,ribosomes are found either free in the cytoplasm or attached to the rough endoplasmic reticulum.
Therefore,ribosomes are universally known as the protein factories of the cell.

(C) Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells.
They are primarily composed of ribosomal $RNA$ $(rRNA)$ and various proteins.
Unlike chromosomes,they do not contain $DNA$ as a structural component.
Therefore,the correct composition is $RNA$ and proteins.

(C) Ribosomes are small,dense,granular structures composed of $RNA$ and proteins. They are not membrane-bound organelles. Their primary function is to serve as the site for protein synthesis in the cell. During this process,ribosomes translate the genetic code from mRNA into a specific sequence of amino acids to form polypeptide chains.

(A) The $Nucleolus$ is a spherical structure present within the $Nucleus$ of eukaryotic cells. It is the site of active ribosomal $RNA$ $(rRNA)$ synthesis and the assembly of ribosomal subunits. Therefore,the nucleolus is often referred to as the 'factory of ribosomes'.

(B) polysome (or polyribosome) is a structure formed when several ribosomes attach to a single $m-RNA$ molecule to translate it simultaneously into multiple polypeptide chains. This process increases the efficiency of protein synthesis within the cell.

(D) polysome (or polyribosome) is a structure formed when several ribosomes attach to a single $mRNA$ molecule.
This structure allows for the simultaneous translation of a single $mRNA$ strand into multiple copies of the same polypeptide chain.
Therefore,a polysome is a chain of ribosomes.

(A) The term "Palade particles" refers to ribosomes.
These were first observed by George Palade in $1955$ under an electron microscope.
Ribosomes are dense, granular structures composed of $RNA$ and proteins, and they are not membrane-bound.
They are the sites of protein synthesis within the cell.