The Nucleus Flashcards
What are the 7 main structures of the nucleus?
nuclear envelope
lamina
nuclear pores
matrix
nucleoplasm
perinuclear space
chromatin
T or F: all DNA is located in the nucleus
FALSE, some DNA is in the mitochondria and chloroplasts
About what percent of a cell’s volume does the nucleus occupy?
~10%
Describe the nuclear envelope
2 membrane bilayers separated by a 10-50 nm space (perinuclear space) that surrounds the nucleus
Each membrane has its own complement of proteins
Describe the perinuclear space
the 10-50 nm space between the two membrane bilayers of the nuclear envelope
How many membranes does the nuclear envelop consist of ?
2 membrane bilayers
What structure is the perinuclear space continuous with?
the ER lumen
The outer nuclear membrane is continuous with which structure?
the ER membrane
T or F: the rough ER membrane is the only membrane that can be have ribosomes attached
FALSE, the outer nuclear membrane can also be studded with ribosomes
Where are the two membrane bilayers (nuclear envelope) fused?
at nuclear pores
Describe nuclear pores
protein complexes that are the entry and exit of the nucleus
How many nuclear pores does the average mammalian cell contain?
thousands
Describe the nuclear lamina
A thin, filamentous meshwork on the inner surface of the nuclear envelope in animal cells
What is the function of the nuclear lamina?
Structural support for the nucleus, especially the envelope
to keep it round
What are the filaments of the nuclear lamina made of?
Lamina proteins
How is the lamina network assembled and disassembled?
by lamin phosphorylation
Why would the lamina network need to assemble and disassemble?
lamina would need to disassemble for cell division to separate cells and then would need to be reassembled in each new cell
During interphase, what 4 things would we see in the nucleus?
- nuclear matrix
- nucleoplasm
- chromosomes
- nucleolus
What is the nucleoplasm?
the fluid inside the nuclear envelope
What would the structure of chromosomes be during interphase?
highly extended fibres with both DNA and chromatin protein
Describe the nucleolus
an irregularly shaped electron dense region in the nucleus that functions in ribosomal RNA and ribosome synthesis
What is the function of the nucleolus?
ribosomal RNA and ribosome synthesis
Describe the nuclear matrix
a dynamic meshwork of insoluble filamentous scaffolding proteins within the nucleus
What is the nuclear matrix analogous to?
cytoskeleton in the cytosol