module 4: nucleus

the _ membrane of the nuclear envelope runs continuously with the membrane of the _ _.

outer, rough er

Which structural component of the nuclear pore acts as a barrier to prevent the passage of large molecules?

fg-nups

Which molecule is known as a molecule switch, driving the import/export of proteins across the nuclear pore? 

Ran

Which enzyme is responsible for remodeling mRNA transcripts as they exit to the cytoplasmic side of the nuclear pore? 

helicase

In a nondividing cell, sequences of DNA that don't contain a lot of genes or contain genes that aren't used in the cell become highly condensed into _

heterochromatin

Heterochromatin is condensed by histone _

methylation

Histone methylation promotes _ _

gene silencing

For DNA that contains genes that will be highly utilized in the cell, histones are _

acetylated

Acetylated histones form _

euchromatin

Euchromatin allows for _ _

gene expression

Where would you expect to find replication factories and transcription factories in the nucleus? 

interior associated with euchromatin

Which nuclear body is the most prominent in the nucleus? 

nucleolus

Polycomb bodies house clusters of proteins that __ transcription by __ lysine residues on histone 3. These nuclear bodies are associated with __

repress, methylating, heterochromatin

Cajal bodies and nuclear speckles mediate the assembly and storage of _ which play an important role in pre-mRNA processing. 

snRNPs

_ _ prevents large molecules from passing and permits small, water-soluble molecules.

nuclear pores

nuclear _ form a _ _ with chromatin and transcriptional machinery.

nup, nuclear basket

proteins needing to be imported must need _ _ _

nuclear localization signal

proteins that have nls bind to nuclear transport receptors called _

importins

protein trafficking pathway

proteins with nls bind to importins, prc interacts with cytoplasmic filaments, prc goes thru pore by fg-nups, proteins dissociates from importin by ran gpt

what only functions in the nucleus that regulates import/exports for gene expression?

transcription factors

explain how gene expression is regulated by transport

transcript factors mask nuclear local signal with cytoplasmic proteins, phosphorylation can alter nuclear

where does heterochromatin located?

edge of the cell, around nucleolus

where does euchromatin located?

central of cell

euchromatin is transcriptionally _.

active

heterochromatin is transcriptionally _.

repressed

euchromatin is ? packed chromatin that is transcriptionally ? and gene ?, allowing access for rna ? and ? ?.  

loosely, active, rich, polymerase, transcription factors

heterochromatin is ? condensed chromatin that is gene ? and is transcriptionally ? because the ? structure blocks access to the ? ?.

tightly, poor, repressed, compact, transcriptional machinery

what have distinct volume-occupying regions in the nucleus where individual chromosomes are located?

chromatin territories

what has precise, large, 3-d positioning of specific positioning of specific chromatin segments in the nuclear space?

chromatin localization

what factory is concentrated in the heart of the nucleus where euchromatin is located?

replication

what factory occurs in the sites with. clustered rna polymerase?

transcription

nuclear bodies are ? which promotes chemical reaction by concentrating molecules.

membraneless

cytoplasmic organelles are ? in the cytoplasm with distinct structures and specialized functions.

membranous