Structure Of The Nucleus (L10) Flashcards
Complexes made of ribosomal RNAs & proteins
Ribosomes
Where are the bound ribosomes attached to?
Where are the free ribosomes found?
- in the rough ER
- in the cytoplasm
What are the functions of ribosomes?
- carry out translation = which is essentially the process of making proteins from amino acids
PROTEIN SYNTHESIS
This organelle contains most of the cell’s genes, it is the most prominent organelle of a cell.
Cell’s control centre = so controls activities going on in and out of the cell
Nucleus
What surrounds the nucleus? What is its function?
- the nuclear envelope.
- composed of two membranes made of a phospholipid bilayer (its outer membrane is linked with the ER)
- it contains tightly packaged DNA (well the nucleus as a whole kinda does)
What is the inner surface of the nuclear envelope lined by? What is it made of?
Nuclear lamina = which are made of intermediate filaments
Remember: intermediate filaments are supercoiled/intertwined microfilaments that form permanent structures. Helps to anchor the cell
What is the function of the nuclear lamina? What happen if it is impaired?
- it maintains shape of the nucleus and this shape allows the DNA to be packed efficiently and tightly
- if nuclear lamina is defective, cells cannot produce normal lamina, thus their nuclei are unable to retain a spherical shape = results in abnormal features
These are channels made of proteins. They control the movement of molecules in and out of the nucleus.
Nuclear pores.
When molecules move between the nucleus and cytoplasm.
Nucleocytoplasmic exchange.
What usually goes from the nucleus to the cytoplasm?
mRNA/tRNA/ribosomal subunits.
MRNA carries genetic information
TRNA/ribosomal subunits are needed to make proteins.
What usually goes from the cytoplasm to the nucleus?
Control signals/building materials
Remember: the nucleus is the control centre of the cell, so it needs some sort of system to direct the kinds of controls it needs to put out.
- control signals are used to turn a gene on/off
- building materials are to build RNA molecules
This is a non-membrane bound specialised region within the nucleus that is responsible for making ribosomal RNA and ribosomal subunits.
Nucleolus
How is DNA organised in the nucleus?
Through histones proteins. The DNA double helix wraps around histones.
What is a nucleosome?
The bead formed when the DNA double helix interacts wth the histones proteins.
These are areas of the nucleus that are less dense and contains frequently used genes.
Euchromatin
