Q:

What is the function of a nucleolus?

A:

Quick Answer

The function of the nucleolus is to transcribe DNA into ribosomal RNA and assemble rRNA into ribosomal subunits. The creation of rRNA is important because rRNA makes up ribosomes which are responsible for protein synthesis in the cell.

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What is the function of a nucleolus?
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Full Answer

In order for transcription to occur, a protein called RNA polymerase binds to DNA at its promoter region. Transcription factors and proteins pull apart DNA's double helix so that polymerase can then transcribe one strand of the DNA to create single-stranded RNA. Transcription ends when polymerase reaches a terminator sequence on the DNA.

When DNA is transcribed into rRNA in the nucleolus, three or four (depending on the organism) distinct rRNAs are produced. These rRNAs are combined with proteins in order to assemble a large ribosomal subunit and a small ribosomal subunit. The subunits are then exported from the nucleolus and nucleus to the endoplasmic reticulum and the cell's cytosol in order to carry out the process of translation, or protein synthesis.

Nucleoli are made of proteins, DNA and RNA and are contained within the cell's nucleus. They don't have membranes, so they can disassemble when the cell divides during mitosis. While humans only have one nucleolus per cell, other organisms exist that can have cells containing multiple nucleoli.

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Related Questions

  • Q:

    What is the purpose of the nucleolus?

    A:

    The nucleolus works to transcribe ribosomal RNA (rRNA) and it forms incomplete ribosomes by combining proteins and rRNA. Other functions of this structure include transporting molecules, vital substances and ions to ensure efficient cell metabolism.

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  • Q:

    Where are ribosomes produced?

    A:

    In the cells of eukaryotic organisms, the subunits that will become ribosomes are produced within the subnuclear structure called the nucleolus, and the subunits then combine in the cell's cytoplasm to become functioning ribosomes. Because the ribosomes are the protein manufacturers of a cell, the size of the nucleolus can take up as much as 25 percent of the volume of the nucleus in cells that require large amounts of protein. Most eukaryotic cells contain only one nucleolus, but certain species can contain several.

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  • Q:

    What are ribosomes composed of?

    A:

    A ribosome consists of two subunits: the large and small subunits. The materials that make up ribosomes are ribonucleic acid, or RNA, and proteins, with approximately 60 percent of a ribosome being made of ribosomal RNA and the other 40 percent consisting of proteins, according to Florida State University.

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  • Q:

    What are nucleotides the building blocks for?

    A:

    According to Purdue University, nucleotides are used to construct nucleic acids, including DNA, tRNA, rRNA and mRNA. Nucleic acids are long polymers of nucleotides that store and transfer information and regulate processes within the cells of all life forms on Earth.

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