3.1.5 The Nuclear Envelope: The Initial Tour

Question 1

central dogma

Answer 1

• states that DNA makes RNA, and RNA in turn directs protein synthesis. In the eukaryotic cell the nucleus houses the DNA

Question 2

In living organisms structure and function are intimately connected. At the cellular level, the many complex functions of the nucleus are evidenced by its structure. The following are key structures of the nucleus:

Answer 2

• the nucleolus, the site for ribosomal synthesis
• the nuclear envelope, a double membrane that surrounds the nucleus and contains pores
• the nuclear lamina, a layer of structural proteins that holds the nucleus together and keeps it intact.

Question 3

note

Answer 3

• Looking at the illustrations at the left, you can see that a double outer membrane, also called the nuclear envelope, surrounds the nucleus. Pores in the envelope allow substances to pass through. The outside of
  the nuclear envelope is dotted with ribosomal subunits that are budding off.
• Inside the nucleus the nucleolus (the circular region) is the site for ribosomal synthesis. The nucleolus contains DNA coding for ribosomal RNA. Running along the inside of the nuclear envelope is a structure called the nuclear lamina, which is comprised of structural
  proteins that serve to hold the nucleus together and keep it intact.

Question 4

True or false?

The nucleolus is a region in the nucleus where ribosomes are formed.

Answer 4

• true

Question 5

What is the name of the double membrane that surrounds the nucleus?

Answer 5

• nuclear envelope

Question 6

Which statement regarding the nucleus is not true?

Answer 6

• The nucleus is always found in the center of the cell

Question 7

Concerning the nuclear envelope, which statement is true?

Answer 7

• The inner and outer membrane of the nuclear membrane are perforated by nuclear pores

Question 8

What is the main function of the nuclear lamina?

Answer 8

• The nuclear lamina functions in reinforcing the shape of the nucleus