what is a nuclear envelope course hero

What is the nuclear envelope?

The nuclear envelope is made up of a double membrane structure that provides a barrier between the nuclear contents and the cytosol: the inner nuclear membrane and outer nuclear membrane. They're connected together, but their protein compositions are different.

What is the inner nuclear membrane?

The inner nuclear membrane contains integral and peripheral membrane proteins that anchor the nuclear envelope to the lamina, which is a sturdy protein meshwork that gives the nucleus its structure and shape.

What is the nucleus of a cell?

In this lesson, we've seen that the nucleus of a cell is surrounded by a double membrane called the nuclear envelope. The nuclear envelope has several functions. First, it provides a physical barrier between the cytosol and the nuclear contents. Second, it is attached to the lamina, which gives the nucleus its sturdy structure and its shape.

How are proteins transported into and out of the nucleus?

They are transported into and out of the nucleus through the nuclear pores, which are large protein complexes that penetrate through both membranes of the nuclear envelope. Like guards or doormen of the nucleus, the nuclear pores regulate which molecules can enter and exit the nucleus.

Which compartment is the outer nuclear membrane?

As you can see in the diagram, the outer nuclear membrane is contiguous with the endoplasmic reticulum (ER), which is the intracellular compartment where lipids, as well as proteins that are going to be secreted or inserted into membranes, are made.

What is the NLS?

The NLS is like a protein's ID card that allows the protein access into the nucleus. The details of active nuclear transport are still being worked out by scientists, but somehow the NLS allows the nuclear pore to open up wider so that larger molecules can go through. Lesson Summary. Let's review. In this lesson, we've seen that the nucleus ...

What is the shape of the nucleus?

In most cells, the nucleus is sphere-shaped, and this diagram shows a cross-section. We'll go through each structural component of the nuclear envelope and learn about their functions at the same time.

Outer Membrane

The outer membrane is a lipid bilayer membrane. This means that it is made up of two layers of lipids that separate the cytoplasm from the perinuclear space, the space between the inner and outer membranes. The outer membrane is contiguous with the endoplasmic reticulum, which is involved in lipid and protein synthesis.

Inner Membrane

The inner nuclear membrane is also made of a lipid bilayer that separates the perinuclear space from the nucleoplasm. As mentioned previously, it is connected to the outer membrane by nuclear pores. It is covered in nuclear lamina which stabilize the nuclear envelope, giving the nucleus its structure and shape.

Nuclear Pores

A nuclear pore is a protein-lined hole in the nuclear envelope that allows molecules to move into the cell nucleus. The nuclear pores pass through both the inner and outer membranes. Each nuclear pore is a large complex of proteins that allow small molecules and ions to diffuse into the nucleus through a channel.