the nucleus

approx what % of the cytoplasm does the nucleus occupy ?

10

who first observed the nucleus and how ?

Leeuwenhoek (1719) using light microscope with increased mag

who coined the term nucleus ?

Brown (1831)

average size of nucleus

2 - 10 um

the relationship between volume of cytoplasm and nucleus is…

linear

example of cell with non-spherical nucleus

neutrophils

example of cell with multiple nuclei

hepatocytes, osteoclasts

nucleolus

condensed area of chromatin, site of ribosome synthesis

granules

rRNA being packaged with cytoplasmic proteins

nucleoplasm

viscous part of nucleus

chromatin

condensed DNA

chromosomes

chromatin ready for cell division

nuclear envelope

membrane barrier between nucleoplasm and cytoplasm

what is the space in between the 2 membranes of the nuclear envelope called ?

perinuclear space

nuclear lamina

protein lining which binds to chromatin and nuclear components

what is the function of the nuclear lamina ?

mechanical support, chromatin organisation, regulation of cell division, stabilises nuclear pore complexes

nuclear pore complex

protein complex that allows for movement of materials in and out of nucleus

where would you find more NPCs

in more active cells

how are chromosomes formed ?

negative DNA wrapped around positive histone proteins to form chromatin, then wound into loops to form chromosomes

gene

sections of chromosomes which code for specific characteristics

how does the presence of a nucleus allows eukaryotes to have a higher level of gene regulation ?

it separates the processes of transcription and translation

transcription factors

proteins involved in process of converting/transcribing DNA into RNA

how is mRNA modified pre-translation ?

splicing to remove introns, capping and addition of poly-A tail

active nuclear import

selective movement of large proteins and rNA via NPC

passive nuclear export

free diffusion of small molecules

NPC components

cytosolic filaments, cytosolic ring, pore ring, nuclear ring, nuclear basket

where would you find scaffold nuclear porins ?

in the cytosolic and nuclear rings

nuclear basket

aids gene tethering and membrane curvtaure

which protein recognises the specific signal sequence on cargo-proteins and transports them from cytoplasm into nucleus ?

importins

what causes the release of cargo once translocated into the nucleus ?

binding of RanGTP

how is RanGTP recycled ?

RanGTP-exporting complex translocated back into cytosol where RanGAP hydrolyses GTP to GDP (inactive) NTF2 translocate RandGDP back into nucleus where GEF phosphorylates GDP back to GTP re-activating Ran

approx. how many unique proteins form the NPC ?

30

which protein is responsible for the exchanging of GDP for GTP on the Ran protein found within the nucleus ?

RanGEF

Ran

monomeric G protein

Ran is only functional in what state ?

GTP bound

RanGAP is found in high concentrations in…

cytoplasm

RanGEF is found in high concentrations in…

nucleoplasm

where are granules and fibrils found ?

nucleolus

proto-eukaryotic model

evolutionary theory based on a progressive increase in complexity without need for endosymbiotic stage

proteins destined for the cytoplasm contain a specific sequence known as a..

nuclear export signal

what is the main function of the eukaryotic nucleus ?

control gene expression within cell