Question | Answer |
perinuclear space | the enclosed space between the inner and outer unit membranes of the nucleus |
nuclear pore | located where the inner and outer nuclear membranes fuse allowing material to be transported in and out of the nucleus |
heterochromatin | inactive and condensed chromatin that can be seen under light microscopy (basophilic and electron dense) |
euchromatin | actively transcribing chromatin that is not visible through light microscopy and is only lightly stained under EM |
nucleosome | structure containing 4 histones and the DNA wrapped around them |
solenoid | the coiling of nucleosomes results in this structure |
histone | protein which functions to maintain chromosome structure and gene activity |
nucleolus | structure within the nucleus where ribosomes are made |
nucleolar organizer | part of nucleolus that contains the DNA which codes for rRNA (transcription occurs here) |
pars fibrosa | part of nucleolus where rRNA strands gather |
pars granulosa | part of the nucleolus where maturing ribosomal subunits are found |
nuclear matrix | scaffolding with the nucleus composed of composite structure proteins and fibrillar material termed the nucleoskeleton; attached to the fibrous lamina |
fibrous lamina | protein structure underneath the inner nuclear membrane |
nucleolar associate chromatin | heterochromatin that is attached to the nucleolus; function unknown |
colchicine | used to arrest dividing cells in metaphase |
Klinefelter's syndrome | sex chromosome abnormality; XXY |
Barr body | inactive X chromosome found in cells with multiple X chromosomes |
cyclin-dependent protein kinases (CdKs) | phosphorylate selected enzymes involved in the cell cycle |
cyclins | proteins that activate CdKs by binding them |
P53 | protein that checks DNA for damage at G1; binds DNA and blocks kinase activity to prevent replication |
polyploidy | result of mitosis with no cytokinesis; e.g. megakaryocytes |
chromosome mosaicism (mixoploidy) | cells having a variable number of chromosomes; results from non-disjunction or anaphase lagging during mitosis |
necrosis | accidental cell death due to microbes, chemicals, etc. |
karyolysis | disintegration and dissolution of the nucleus; occurs during necrosis |
pyknosis | irreversible condensation of chromatin; occurs during necrosis |
apoptosis | programmed cell death; can be triggered by DNA damage |