The Nucleus Flashcards
What are the functions of the nucleus?
Storage of DNA, genetic template.
What are the benefits of compartmentalised genetic material in eukaryotes?
It protects the DNA, increases the surface area for membrane-localised reactions, increases efficiency of transcription and synthesis and it allows more ways to regulate gene expression.
What is the endoplasmic reticulum?
It is the site of protein production by ribosomes, protein folding and glycosylation (adding sugar molecules).
What does lamina mean?
A thin plate.
What are the properties of the nuclear lamina?
It is related to intermediate filaments, it forms a meshwork on the inner nuclear membrane and associates with DNA (functional) and
What is a LINC complex?
Protein complexes that link the nuclear lamina with the cytoskeleton.
What do nesprins do?
They connect to different cytoskeleton elements.
What does PLF stand for?
Pore-linked filaments.
What does Titin do?
It binds chromosomes and lamina.
What does NuMa stand for?
Nuclear mitotic apparatus.
What is nuclear actin?
Short filaments or monomeric (G-actin).
What are chromosomes?
DNA-protein complexes that are specially packaged for cell division.
What is chromatin?
A complex of DNA, RNA and proteins.
What is Euchromatin?
True chromatin that is less visible by microscopy. It is not so densely packed and makes up the majority of the genome and is localised in central part of the nucleus.
What is heterochromatin?
Different chromatin that looks dark under the microscope. It is tightly packed condensed DNA. It is localised around the lamina and nucleoli.
What are the different types of RNA?
mRNA, rRNA, tRNA.
What substances are used to import proteins from the cytoplasm?
RNA polymerase, ribosomal proteins, transcription factors and all other structural proteins.
What is the nuclear pore complex?
Ring structure with 8-fold symmetry, 30 nuclear pore proteins and has a central channel filled with FG+-Nups that form selective barriers to transport.
What are the two kinds of movement through the NPC?
Passive transport and facilitated transport.
What does passive transport involve?
Small molecules and proteins.
What does facilitated transport involve?
RNAs, larger proteins, macromolecular complexes.
What are the energy sources required for facilitated transport?
ATP hydrolysis for mRNA, GTP hydrolysis for proteins, tRNA and ribosomes.
What is mRNP?
mRNA-protein complex.
What happens in the mRNA export processing complex?
It includes processing, capping, splicing proteins as well as export factors.
How does mRNP go out or into the nucleus?
Through nuclear pore complexes.
What is required for mRNP to leave the nucleus?
ATP hydrolysis - it releases Dbp5 in the cytoplasm and mRNP remodelling.
What are importins?
Nuclear transport receptors.
What do importins do?
They bind to cargo proteins in the cytoplasm and interact with FG_Nups and release cargos in the nucleus.
What enables cargo release?
It is enabled by Ran-GTP binding to importin-beta. This causes a conformational change that results in the complex coming apart.
