cell bio ch 8

what is the nucleus?

a large organelle that holds DNA

what is the site of the nucleus for?

transcription and DNA replication

what is the nuclear envelope?

a lipid membrane surrounding the nucleus

what is the nucleus surrounded by?

a pair of phospholipid membranes

what is the function of the nuclear envelope?

controls what enters and leaves the cell

what are the functions of the perinuclear space?

controls nucleus shape and helps connect nucleus to other organelles

what are nuclear pores?

protein channels that allows things in and out

what is a nuclear pore complex?

protein pores that surround membranes

what do nuclear pore complexes allow transport of?

tRNA, mRNA, and proteins

what is chromatin?

DNA and proteins packed together

what are the types of nuclear transport?

exporins and importins

what are karyopherins?

proteins that help transport molecules across the nuclear envelope

what do exporins do?

export molecules from the nucleus

what do importins do?

import molecules to the nucleus

what sequence do some proteins that are imported to the nucleus have?

nuclear localization sequence

what is the nuclear localization sequence bound by?

importins

what is carried through the nuclear envelope?

protein cargo

what happens during nuclear import?

importin carries cargo into the nucleus, protein Ran detaches the cargo and binds importin, and then Ran carries importin back out

what happens during nuclear export?

an exportin attaches to cargo, Ran attaches to exportin to carry them out, and then Ran and exportin come back in

what is RNA transport?

exporter complexes made of proteins that export RNA

what is the nuclear lamina?

protein network lining inside of the nucleus

what does the nuclear lamina control?

the nucleus shape and regulation of chromatin and gene expression

what is heterochromatin and where is it?

condensed and inactive DNA/ attached to nuclear lamina

what is euchromatin and where is it?

decondensed and active DNA/ middle of nucleus

what are nuclear bodies?

subregions within the nucleus with special regions

what are the structures of the nucleus?

nuclear envelope, nuclear pores, chromatin, nuclear lamina, and nuclear bodies

how do distant DNA regions interact?

in functionally similar hubs

what are transcription hubs?

regions where many genes are transcribed

what are replication forks?

regions where DNA is being replicated

what is the nucleolus?

a dense region of the nucleus involved in ribosome production

what happens in the nucleolus?

rRNA is transcribed and processed, ribosomal proteins are imported from the cytoplasm, ribosomal proteins and rRNA are assembled into ribosomes, and mature ribosomes are exported

what are cajal bodies?

regions involved in RNA splicing

where are components of the splicesome assembled and stored/

cajal bodies and nuclear speckles