Q:

What controls the activities of a cell?

A:

The cell nucleus is the command center and thus controls the activities of the eukaryotic cell. A double-walled cell nuclear envelope separates the nucleus from the cytoplasm and controls its shape while allowing chemical compounds to pass to and from the nucleus to control other activities in the cell. The nucleus contains the chromosomes, consisting of DNA, that regulate cell growth and reproduction.

The nucleus contains the nucleolus, a dense RNA and protein structure. Inside this structure are the organizers that form chromosomes with genes necessary for ribosome synthesis. The nucleus also regulates protein synthesis in the cytoplasm using messenger RNA, which travels to the cytoplasm through pores in the nuclear envelope. Once there, messenger RNA is translated using ribosomes and transfer RNA in the production of proteins. The nucleus regulates the molecules allowed through the pores of the membrane to prevent some larger molecules entering from the cytoplasm.

In animals, the nucleus is the largest cell organelle. Human cells have a nucleus that averages between 11 and 22 micrometers in diameter and occupies approximately 10 percent of the cell volume. It is large enough to observe and study using an electron microscope. Scientists believe mutations occurring in the nucleus are a key to developing diseases as well as the body's response to these diseases.

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Related Questions

  • Q:

    Why is the nucleus called the control center of the cell?

    A:

    The nucleus can be thought of as the control center of a eukaryotic cell because it contains most of the genetic material that carries the instructions for the cell's operations. Inside the nucleus, DNA directs the sequence of chemical steps needed for the synthesis of proteins and, by way of the proteins' action, it controls the metabolism of the rest of the cell.

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  • Q:

    How do you define "animal cell"?

    A:

    An animal cell is defined as a eukaryotic cell in which all the organelles are contained in membranes. Organelles included in an animal cell are a nucleus, the centrioles, an endoplasmic reticulum, a golgi complex, lysosomes, the mitochondria and ribosomes.

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  • Q:

    Who discovered the cell nucleus?

    A:

    Robert Brown discovered and named the cell nucleus in the 19th century. The discovery was made when he was trying to determine why pollen grains moved inconsistently in the water.

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  • Q:

    What is the structure of a spirogyra cell?

    A:

    Spirogyra cells contain chloroplasts, a large vacuole, a cell nucleus, cytoplasmic strands holding the nucleus in place and two cell walls. They are simple plants, with no specialized cells for absorbing water, transporting nutrients or reproduction.

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