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Nucleoplasm

What is Nucleoplasm

Similar to the cytoplasm found inside a cell, the nucleus also contains a jelly-like substance called nucleoplasm. It is also known as karyoplasm, karyolymph, or nucleus sap. It remains completely enclosed within the nuclear membrane or nuclear envelope.  The primary function of nucleoplasm is to suspend other nuclear structures within it.

Where is the nucleoplasm located

As stated, nucleoplasm is located in nucleus of eukaryotic cells, including both plant and animal cell.

Nucleoplasm

Structure

Chemical composition

The nucleoplasm has a complex chemical composition. It is a highly gelatinous, sticky liquid. It is mainly made up of water, nuclear proteins, and other inorganic and organic substances such as nucleic acids, proteins, enzymes, and minerals. The soluble, fluid portion of the nucleoplasm is called the nucleosol or nuclear hyaloplasm.

The nucleoplasm contains two types of nuclear proteins, histone or basic proteins and non-histone or acidic proteins. The common nucleic acids of the nucleoplasm are DNA and RNA.

The nucleoplasm also contains critical enzymes that are necessary to catalyze reactions occurring in the nucleus. The most vital enzyme found in the nucleoplasm is DNA polymerase, as it helps produce DNA from nucleotide bases. Some other enzymes found in nucleoplasm are hexokinase, 6-P-gluconic dehydrogenase, TPN-linked isocitric dehydrogenase, P-fructokinase, glucose-6-P dehydrogenase, and glutamic dehydrogenase.

Parts of the Nucleoplasm

i) Nucleolus

It is the major ribosome manufacturing center within the nucleus. Specially designed proteins enter the nucleus through nuclear pores to create ribosomal RNA, which in turn produces ribosomal subunits. These subunits are then pushed out into the rest of the nucleus, where they are processed into fully functional ribosomes. The ribosomes can then attach to the nuclear membrane, although they are also found throughout the cytosol and the endoplasmic reticulum.

ii) Nucleotides

Nucleoplasm also houses nucleotides, the fundamental building blocks of DNA and RNA. All the nucleotides consist of a base (double-ringed purine or a single-ringed pyrimidine), a phosphate group, and deoxyribose (for DNA) or ribose (for RNA) sugar. The five most common nucleotide bases are adenine, guanine, cytosine, thymine, and uracil. These bases can be combined and methylated to form a wider variety of complex bases that form the fundamental genetic material.

iii) Chromatin

It is a molecular complex of DNA, RNA, and proteins that help them in folding. Chromatin specifically works to shrink long strings of DNA so that it can better fit inside a cell. It also prevents the entangling of the strings during DNA folding and improves the efficiency of replication. Chromatin is also closely linked to gene repression, DNA transcription, and gene expression.

iv) Nuclear Matrix

It can be found throughout the nucleus and plays an essential role in maintaining the structure of the nucleus. It also aids in organizing the genetic material of the cells.

Function

  • Serves as a suspension substance for the organelles inside the nucleus.
  • Maintain the shape and structure of the nucleus.
  • Helps in the transportation of materials that are vital to cell metabolism.
  • Act as the site for various nuclear events and activities, for instance, gene expression, DNA replication, and DNA repair.
  • Synthesize ribosomal RNA (rRNA) that in turn produces two ribosomal subunits, large and small. After exiting the nucleolus, these subunits combine to form a ribosome.

Difference between Nucleoplasm and Cytoplasm

NucleoplasmCytoplasm
Fluid part of the nucleus, containing nucleolus and other nuclear structures.Fluid mass of the cell, containing cellular organelles.
Found inside the nucleus.Found inside the cell, but outside the nucleus.
Enclosed by the nuclear envelope.Enclosed by the cell membrane.
Found only in eukaryotic cells.Found in all cells.

Article was last reviewed on Thursday, December 23, 2021

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