Nucleus Flashcards
Which type of cells do NOT contain a nucleus?
red blood cells (RBCs)
heterochromatin
highly condensed chromatin that contains genes that are inactive in a particular cell
constitutive heterochromatin
every cell has the same
facultative heterochromatin
changes from cell to cell
euchromatin
lightly staining material - dispersed form of chromatin where most transcribed genes are located
chromatin
complex of DNA and proteins
nucleolus
a small area within the nucleus that contains DNA in the form of transcriptionally
active ribosomal RNA (rRNA) genes, RNA, and
proteins. The nucleolus is the site of rRNA synthesis and contains regulatory cell-cycle proteins.
when do you see chromosomes?
only during cell division
only see chromatin during interphase
nuclear envelope
double membrane surrounding nucleus
outer portion is continuous with rough ER
how are heterochromatin and euchromatin separated?
protein folds are either hydrophobic or hydrophilic
like oil and water
nuclear pores
complex structures that allow things in and out in a selective fashion
THEY ARE ALL THE SAME
accessory proteins help nuclear pores become selective
nuclear lamina
fibrous layer constructed of intermediate filaments and lamin proteins
structural support
nucleosome
length of DNA coiled around a core of histones
Progeria Syndrome (hutchinson-Gilford)
Nucleus lacks integrity due to mutations in lamins (50-amino acid deletion)
nuclear lamina supposed to provide support to nuclear membrane
causes premature aging, cancer, and other conditions associated with aging
what happens when nucleus is not shaped correctly?
some processes do not work
Ex: deffective repair of DNA damage
accessory proteins
bind to nuclear pores and change conformation
nuclear import signal
most proteins make it into the nucleus have this sequence
t-antigen stain to visualize whether proteins make it into the nucleus or stay in cytoplasm
alternative splicing
a given exon will have different parts of it included or excluded
