Nucleus

Question 1

Describe nuclear pores and their function.

Answer 1

Regulates transport into and out of nucleus
• RNA, protein, ions and other small molecules
• Bi-directional
Large multi-subunit complex
• More than 50 proteins
• 125 x 106 Daltons
Pore size ranges from 9 - 25 nm
• Adjusts to size of transported molecule
• Small molecules freely diffuse
• Large molecules require a specific transport
mechanism

Question 2

What are the functions of the nucleus?

Answer 2

Function
• DNA replication
• Transcription
• RNA processing
- Separated from cytoplasmic functions by double
membrane
• Protein synthesis
• Metabolism
- Requires transport mechanism
• Regulation of replication and transcription
• Molecules required for replication, transcription and translation

Question 3

What is the Nuclear Laminae and how does it function?

Answer 3

• Meshworkunderlying the inner nuclear
  membrane
  • Provides shape and stability to
  nuclear envelope

Question 4

How does the Nuclear Lamina function?

Answer 4

• Structural
  • Determines size and shape of nucleus
  • Provides strength
  • Prevents deformation • Determines position of nuclear pore complexes
  • Binds nuclear pore proteins
• Metabolic
  • Bind chromatin
  • Associated with internal regions active in replication,
  transcription and RNA processing and DNA repair • May be involved in gene silencing

Question 5

What is the structure of the Nucleus?

Answer 5

> Contains genetic material packaged as chromatin
• DNA and associated proteins 
> Other functional domains
• RNA metabolism 
> Surrounded by a double membrane
• Continuous with the ER
• Mediates transport between
nucleoplasm and cytoplasm

Question 6

What are the three components of the nuclear membrane?

Answer 6

1. Nuclear envelope (inner and outer membrane)
2. Nuclear Lamina
3. Nuclear pores