The Nucleus Flashcards
What are the components of the nucleus?
- Nuclear envelope
- Nuclear pore
- Nucleolus
- Nucleoplasm
- Chromosomes
How is the endoplasmic reticulum related to the nucleus?
The endoplasmic reticulum is continuous with the outer membrane of the nuclear envelope
Evolution of the nucleus
Ancient prokaryotic cell with free DNA
Invagination of membrane with the membrane-bound ribosomes attached
Membrane buds away to form nucleus structure with rough endoplasmic reticulum
The inner and outer membrane make up the _______________
Nuclear envelope
What is the perinuclear space?
The space between the inner and outer membrane
At what structures do the inner and outer membrane meet?
Nuclear pores
What is the nuclear lamina?
A protein meshwork
What is the function of the nuclear lamina?
Structural support for nuclear envelope
What are the 3 types of lamina?
Lamina A, B and C
What is the nuclear lamina involved in?
The regulation of genetic activity
What is different about the nucleolus to other organelles?
It is not membrane-bound
What is the function of the nucleolus?
Processes rRNA to produce ribosomal subunits
What molecules are present in the nucleolus? (7 macrocmolecules)
- rRNA genes
- Precursor and Mature RNA
- rRNA processing enzymes
- snoRNPs (small nucleolar RNAs)
- Assembly factors
- ATPases, GTPases, RNA Helicases etc.
- Ribosomal protein subunits
What is DNA in the nucleus packaged into?
Chromosomes
How does DNA form chromosomes in the nucleus?
DNA wraps around histones to form nucleosomes. These coil further to form chromosomes
What does a nuclear pore consist of?
It consists of >50 different proteins. It isn’t just a hole
What does the nuclear pore permit?
Substances to cross the nuclear envelope
What is required for the nuclear pore to allow substances to cross the nuclear envelope?
ATP hydrolysis
In a non-dividing cell, how is the DNA stored?
In loose strands called chromatin
How many subunits make up a nuclear pore?
8 subunits with a central plug
What are nucleoporins?
Proteins that make up the nuclear pore
After what size is a molecule to big for passive diffusion through a nuclear pore and has to be actively transported?
60,000 daltons
Give 2 examples of why Nuclear transport via Nuclear Pore Complexes is necessary.
- Synthesis of DNA histone molecules occurs in cytoplasm and these need to be transported into the nucleus for packaging of DNA
- Ribosomes synthesised in the Nucleolus must be transported into the cytoplasm
