The Nucelus Flashcards
What is coupled protein synthesis
Transcription and translation occurs in the same area
What is decoupled protein synthesis
Transcription occurs in a separate space (inside the nucleus) to translation (outside the nucleus)
What is the nucleolus
The area inside the nucleus responsible for synthesising rRNA
What is the perinuclear space
The in between the two membranes of the nuclear envelope. It is continuous with the rough endoplasmic reticulum
What is the function of nuclear pores
They allow molecules to enter and exit the nucleus. They contain regulatory proteins which control the movement of molecules
What is heterochromatin
Chromatin is the tightly wound DNA that makes up chromosomes. Heterochromatin is tightly wound so appears as a dark region and prevents transcription factors and RNA-polymerase from reading DNA
What is euchromatin
Loosely wound chromatin that can be transcribed by RNA-polymerase. It is not visible under a microscope due to its low density
What is the nucleoplasm
The cytoplasm inside the nucleus. It has its own distinct environment compared to the rest of the cell
What are nuclear lamina
They make up the scaffolding that gives the nucleus its shape and structure, similar to the cytoskeleton.
They are intermediate fibres
The can quickly be broken down into individual monomers and then built back up into a polymer (this is important during mitosis)
The build up and break down of nuclear lamina is controlled by phosphorylation by kinases and dephosphorylation by phototases
What is an NES
Nuclear Export Signal
Proteins with this signal will be imported out the nucleus
The signal is the first 15-20 amino acids in the protein sequence
The protein is moved by exportins
What is an NLS
Nuclear Localisation Signal
Proteins with this signal will be imported into the nucleus
The signal is the first 15-20 amino acids in the protein
The protein is moved my importins
What are the 3 sections of the nucleolus
Nuclear organising region
Pars fibrosa
Pars granulosa
What are histones
The proteins that DNA is wound around.
They represent the first level of DNA compaction
If the histones are tightly packed together then they form Heterochromatin
If the histones are loosely packed then they form euchromatin
How many subunits are in a histone and what are they
8 subunits
4 pairs of 2
H2A, H2B, H3 and H4
