Lecture 7 Nucleus Flashcards
The outer membrane of the nucleus is often surrounded by a mesh of ____ _____
intermediate filaments
The nuclear lamina supports the inner membrane of the nucleus and is primarily composed of _____ A, B, and C
Laminin
Nuclear pores are formed by fusion of the inner and outer nuclear membrane and are associated with the _____ _____ complex
nuclear pore
The nuclear pore complex is a cylindrical aqueous opening that allows passage of small ____ _____ molecoules
water soluble
The nuclear pore complex consists of proteins arranged in _____ symmetry
octagonal
Ions, small molecoules, and proteins less than 60 kDa can diffuse into the nucleus via NPCs. Transport of larger molecules requires nuclear pore _____ proteins
receptor
Nuclear pore receptor proteins are ____ associated and recognize nuclear recognize signals, which are ____ ____ sequences on the protein.
fibril
amino acid
Large proteins recognized by nuclear localization signals are transported into the nucleus via ____ transport
active
Nuclear import-export requires energy in the form of ______ –> _____
GTP
GDP
Specialized proteins called ____ and ____ are needed to move materials across the nuclear pore
importin
exportin
Nucleoplasm is protoplasm surrounded by the nuclear envelope that consits of a ____ ____ and various particles
nuclear matrix
The nuclear matrix acts as a _____ to organize the nucleplasm.
scaffold
The nuclear matrix contains ___ components: including fibrillar elements, the nuclear pore-nuclear lamina complex, and the RNP network. The matrix also contains ____ components involved in transcription and process of mRNA and rRNA
structural
functional
Chromatin resides within the nucleus in 2 forms: ____ and _____
heterochromatin
euchromatin
Heterochromatin appears _____ under TEM and is concentrated at the nucleus periphery and around the nucleolus
darker
Heterochromatin is transcriptionally _____
inactive
Euchromain is lightly stained and dispersed throughout the nucleus and is transcriptionally _____
active
Chromatin consists of double stranded DNA complexed with histones and non-histone acidic proteins that are responsible for _____ synthesis
RNA
Histones contain _____ and ____ that bind to DNA
lys
arg
the _____ is the fundamental packing unit of chromatin
nucleosome
Chromatin resembels beads on a string at the TEM level, with the beads being nucleosomes and the string being ____ DNA
linker
____ chromatin contains an additional histone (H1), which wraps around groups of nucleosomes forming 30-nm fibers, the strutural unit of the chromosome
condensed
Chromosomes become visible during ____ and _____
mitosis
meiosis
Barr bodies are present in nearly all somatic cells of ____ mammals
female
Barr bodies are inactive ____ chromosomes and appear during interphase
X
the _____ is a non-membrane bound, nuclear inclusion of the nucleus
nucleolus
Cancer cells may have large or multiple _____
nucleoli
The nucleolus is generally detectable only when the cell is in _____
interphase
The _____ is protoplasm surrounded by the nuclear envelope. It contains nuclear matrix
nuceloplasm
Nucleosomal histones include H2A, ____, H3, H4, and H1 histones
H2B
