Exam 3 - The Nucleus

Question 1

What are the main structural components of the nucleus?

Answer 1

Nuclear envelope (Outer Nuclear Membrane, Inner Nuclear Membrane), Nuclear Lamina, and Nuclear Pore Complexes.

Question 2

How is the perinuclear space in comparison with the ER lumen?

Answer 2

Identical

Question 3

How is the Outer Nuclear Membrane in comparison with the ER membrane?

Answer 3

Identical

Question 4

How is the Inner Nuclear Membrane in comparison with the ER membrane and the Outer Nuclear Membrane?

Answer 4

Different, The INM contains proteins that are specific to the INM and does not have ribosomes associated to it.

Question 5

Two proteins specific to the INM are Emerin and Lamin B Receptor (LBR). What’s the role of LBR during the re-formation of the nucleus after mitosis?

Answer 5

A bridge is provide so that it’s tightly associated with the NM; nuclear lamina disassembles through phosphorylation NE begins to bubble into vesicles distributed into cytoplasm vesicles facing the inner part of the nucleus will contain lamins associated to proteins specific to the INM lamins have ability to bind to DNA DNA coded by vesicles vesicles surround individual chromosome and fuse formation of larger membrane larger vesicle fuse together reforming the nucleus

Question 6

What’s the main role of the nuclear lamina?

Answer 6

to provide a structure of fibrous meshwork in the nucleus

Question 7

What’s the main structural component of the nuclear lamina?

How is it regulated?

Answer 7

The lamina is made of proteins named Lamins.

regulated by phosphorylation which triggers the disassembly of the scaffolding structure formed by the lamins

Question 8

The nuclear pore complex is enormous; however it is made of only about 35 different proteins. How come?

Answer 8

Each structure is made of 30 proteins, each each replicated 8 times.

Question 9

How many Nuclear Pores are there per nucleus? How is that of any relevance?

Answer 9

3000-4000 pores per nucleus

Question 10

What goes through the Nuclear Pore Complex (NPC)?

Answer 10

Small molecules and proteins that are less than 40kD are allowed to go in and out freely, without the help of importins or exportins.

other molecules and proteins travel through signal specific direction for selective transport.