Biology · Cell: The Unit of Life · NEET
Yes. They are two names for the same thing. NCERT says: several ribosomes attach to a single mRNA and form a chain called polyribosomes or polysome. So in NEET both words mean the exact same structure. Do not treat them as different.
A polysome is MANY ribosomes on ONE single mRNA, not many mRNAs. Several ribosomes line up along the same mRNA strand and each one translates it. This is a common trap: the mRNA is one, only the ribosomes are many.
To make protein faster. If one ribosome makes one polypeptide from an mRNA, then several ribosomes on the same mRNA make several copies of that same polypeptide at the same time. So the cell gets many copies of one protein quickly from a single mRNA.
No. All ribosomes on the same mRNA read the same code, so they all make copies of the SAME polypeptide. The proteins are identical because the mRNA (the message) is the same for all of them.
A ribosome is a single protein-making machine (70S in prokaryotes, 80S in eukaryotes). A polysome is a whole group of ribosomes joined onto one mRNA. So ribosome = one worker; polysome = many workers on one job (one mRNA).
No, they are totally different and NEET mixes them up on purpose. A polysome = ribosomes translating one mRNA (protein synthesis). A nucleosome = DNA wrapped around histone proteins (DNA packaging). Same-sounding words, different topics. If a question asks about ribosomes on mRNA, the answer is polysome, never nucleosome.
Many ribosomes may associate with a single mRNA to form multiple copies of a polypeptide simultaneously. Such strings of ribosomes are termed as
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. Any cell that makes protein can form polysomes. In prokaryotes 70S ribosomes form polysomes on mRNA, and in eukaryotes 80S ribosomes do the same.
No. Ribosomes (and so polysomes) are not surrounded by any membrane. They can float free in the cytoplasm or sit on the rough endoplasmic reticulum, but the polysome itself has no membrane.
They are held together by the single mRNA strand that runs through all of them. The mRNA is the common thread; each ribosome moves along it while translating.
Its function is protein synthesis. NCERT states: the ribosomes of a polysome translate the mRNA into proteins. It speeds up making many copies of the same protein.
