Book : Cell Biology
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Posted by: CHELSEA
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Writer CHELSEA

Nucleus

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The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction. It is commonly the most prominent organelle in the cell.

The nucleus is surrounded by a structure called the nuclear envelope. This membrane separates the contents of the nucleus from the cytoplasm. The cell's chromosomes are also housed within the nucleus. Chromosomes contain DNA which provides the genetic information necessary for the production of other cell components and for the reproduction of life.

Types of Nucleus:

The word 'nucleus' can refer to the center of an atom or the control center of a cell. This lesson will discuss the nucleus of a cell. You have over 200 different types of cells in your body. Some can be really thin and long, like a nerve cell that runs all the way from your spinal cord to your foot. Some, like a fat cell, have a more rounded shape. No matter what your cells look like, there is one important thing they all have in common: a nucleus. This is a control center that is found inside all of your cells at some point during their life. A nucleus is responsible for determining and controlling what a cell looks like and what it does.

Functions of the Nucleus:

The nucleus is an organelle found in eukaryotic cells. Inside its fully-enclosed nuclear membrane, it contains the majority of the cell's genetic material. This material is organized as DNA molecules, along with a variety of proteins, to form chromosomes.  The nucleus is made up of a double membrane nuclear envelope that keeps the entire organelle encased, isolating its contents from the rest of the cell, and the nucleoskeleton which supports the cell as a whole. The nucleus maintains the security of the genes and controls the functions of the entire cell by regulating gene expression. This is why the nucleus is sometimes referred to as the control center, or the "brain," of the cell. 

The nucleus is the site for genetic transcription, while keeping it separated from the cytoplasm. This means gene regulation is taking place in eukaryotic cells that have a nucleus, but that this gene regulation isn't available to prokaryotes. That means the main function of the nucleus is to govern gene expression and facilitate DNA replication during the cell cycle. 

Structure:

A nuclear envelope encloses the nucleus to keep it separate from surrounding materials in the cell. Sometimes substances need to move into or out of the nucleus, and this is possible because there are little holes in the nuclear envelope called nuclear pores. Inside the nucleus is at least one dark-colored mass called a nucleolus. DNA occupies most of the rest of the space inside a nucleus. DNA is genetic material that has the instructions necessary to build proteins. Proteins are responsible for helping with most activities in a cell.


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