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📚 > Physiology > General Physiology > Cells and Molecules_>

Cell Nucleus



The nucleus is the Control center of the cell.


Nuclear Envelope

  • Covers the nucleus.

  • Made up of two layers: an outer membrane and an inner membrane.

Outer Membrane
  • Contains ribosomes.

  • Continuous with the membrane of the rough endoplasmic reticulum.

  • Space in between two layers is continuous with the lumen of the rough endoplasmic reticulum.

Inner Membrane
  • Is smooth.

  • The inner and outer membrane meet at nuclear pores.

Nuclear Pores
  • The pathway between the inside of the nucleus and cytoplasm. For example for the exit of RNA and for entry of signal molecules.

  • Lined by nuclear pore complexes.

Nuclear Pore Complexes
  • Complexes of proteins.

  • Provide permeability selectivity to the pores.

  • Prevents the mixing of proteins on the inner and outer membranes.


Content of the Nucleus

Nucleoplasm
  • Equivalent to cytoplasm outside the nucleus.

DNA
  • The genetic information.

  • Spread in form of chromatin.

  • Takes the form of chromosomes when the cell divides.

Nucleolus
  • Accumulation of RNAs and proteins similar to ribosomes.

  • There can be one or more nucleoli in a nucleus.

Nuclear Lamina
  • Fibrillar protein skeletal near the inner membrane of the nuclear envelope.

  • Provides structural support to the nuclear envelope.

 

Next >>

Next, we will see the endoplasmic reticulum, the site of protein synthesis, and many metabolic reactions.

▶️ Endoplasmic Reticulum
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