Nucleus

The Nucleus of a cell is an organelle enclosed in a membrane, found inside eukarya. It's specialised function is to contain the cell's genetic information, stored inside long strands of DNA molecules, combined with proteins.

Components

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Nuclear Envelope

The Nuclear Envelope is a double layer (so 2 lipid bi-layers) membrane surrounding the nucleole and other genetic material. The two layers are the inner nuclear membrane and the outer nuclear membrane, and they're from 20-40 nm wide.

Nuclear Pores

Nuclear Pores are complex proteins crossing the surface of the Nuclear envelope. They allow the transport of water-soluble molecules (e.g. RNA) through the envelope and out of the nucleus.

These pores make the membranes semi permeable.

Nucleoplasm

The fluid interior portion of the nucleus that everything else is supported by.

Chromosome

A chromosome is a single piece of coiled DNA (one molecule) - an organised structure of DNA and proteins.

Human beings have 46 chromosomes per cell (23 pairs).

Chromatin

Chromatin is the total collection of all DNA molecules and associated proteins in a cell. Its purpose is to package DNA to fit into the small space, protect the DNA, strengthen it for mitosis and control DNA replication.

Nucleole/Nucleolus

The nucleole is the very centre of the cell - it's purpose is to transcribe and assemble ribosomal RNA. When the cell is not dividing it looks like a mass of very long thin fibers.