Nucleus Flashcards
Proteins within the nucleus can be categorized by two types. They are?
Histones and non histones
mRNA, tRNA, rRNA, proteins, chromatin, nucleolus, and the nuclear envelope are all components of…
The nucleus
Small, positively charged basic proteins that form the core of the nucleosome complex
Histones
What are the four characteristics described of Non histones according to lecture?
- Negatively charged acidic proteins
- Regulate transcription
- Involved in DNA repair and replication
- Maintain and convert chromatin structure
When staining heterochromatin, which stain do you use and how does it stain?
for the purpose of the lecture slides. Did not look up to see if there are other stains you can use.
H&E and it stains dark
What are the two types of heterochromatin?
Constitutive and facultative
T/F heterochromatin is not transcriptionally active?
True
T/F Constitutive heterochromatin contains DNA that is not transcribed
True
Euchromatin IS transcriptionally active and stains how with H&E?
Lightly
Ribonucleoproteins, nuclear lamina, and chromatin are associated with?
The inner membrane of the nuclear envelope.
The outer membrane of the nuclear envelope is continuous with the ER, similar in structure to the ER, therefore it must be associated with?…
RIBOSOMES!! You got it dude.
Nuclear lamin codes for at least (#?) proteins.
Lucky 7
How do the three intermediate filaments of the nuclear lamina provide support to the inner membrane of the nuclear envelope?
- during cell division- the lamins become phosphorylated and the nuclear membrane undergoes dissolution
- after cell division- nuclear lamins are dephosphorylated and the membrane is reformed and stabilized
Hutchinson-Gilford Progeria is an example of a mutation involving?
The nuclear lamina
Lamins interact to form?…
Dimers!
Collectively, lamin dimers form?…
The nuclear lamina
Nuclear lamin genes…(Jackson 5 _ _ _ 1,2,3 baby you and me girl…)
A,B,C
RNA processing and transport are thought to occur where?
In the spaces (channels) referred to as interchromosomal domains that separate the domains
What are PML bodies named after?
Named because of the transcription factors involved in acute promyelocytic leukemia (PML)
Where does replication appear to take place?
Well duh, in replication factories.
These are concentrations of mRNA splicing machinery.
Nuclear speckles. You put them on top of your sundae. Mmmm!
They contain the protein coilin and may be sites of Ribonucleoprotein assembly and processing
Cajal bodies. Our cousins from the Bayou!
T/F the nuclear pore complex is bidirectional?
True. It’s a passageway for macromolecules between the nucleoplasm and cytoplasm
Proteins destined to be IMPORTED into the nucleus have a special amino acid sequence. What is it?
Pro-Lys-Lys-Lys-Arg-Lys-Val
Proteins destined for export from the nucleus have what?
Nuclear export signals
T/F molecules < 40-60 kDal can freely pass through the nuclear pore complex
So very true!
Importin alpha/beta and exportin at both what type of major protein that translocate proteins through the pore complex.
Karyopherins
Roughly 30 pore proteins make up the mammalian pore complex called?…
Nucleoporins
Arranged around a central channel, these have an 8-fold symmetry?
Nuclear pore complex.
What’s heterochromatin?
Condensed chromatin (DNA in the nucleus)
What are Barr bodies/drumsticks?
Inactivated X chromosomes.
Or they are brands of ice cream comes.
Which proteins are found on the INNER membrane of the nucleus that is phosphorylated early in eh cell cycle and becomes unstable?
Lamins
Let’s get in the mindset of micro tubular transport to the axon. Going from the cell body to the axon terminus involves?
Anterograde and involves kinesins
The NLS on a specific protein is recognized by?
Importin alpha- component of the nucleocytoplasmic transport complex.
