nucleus quick flashcards

what are the functions of the nucleus

storage & maintenance of most of the cell’s genetic info

control of gene expression through transcription

regulation of protein synthesis machinery through: synthesis of rRNA & assembly of ribosomes in nucleolus

what is the nuclear envelope

consists of two lipid bilayers

inner nuclear membrane is in contact with chromatic

outer nuclear membrane is continuous with the rough ER

what are nuclear pores

inner & outer membrane fused together

facilitate the bidirectional transit of materials between nucleus & cytoplasm

eg. RNAs exit nucleus, proteins, carbs, etc enter nucleus

what are nuclear lamina

line the inner side of nuclear envelope

are a network of intermediate protein filaments that maintain the shape of the nucleus

also anchors interphase chromatin at nuclear periphery

what are chromosomes

one long DNA molecule associated with proteins

some of the proteins help coil DNA and package it within the nucleus

what is chromatin

material that makes up a chromosome that contains DNA and protein

major proteins in chromatin are called histones (packaging elements for the DNA)

chromatin wraps DNA in very tight coil

what is a gene

a length of DNA that codes for a protein

what is a nucleosome

segment of DNA wrapped around 8 histone proteins

2 copies of histones H2A, H2B, H3 and H4 allows DNA to be organized and packed into the nucleus

what are transcription factors

DNA binding proteins that regulate gene expression

what is euchromatin and heterochromatin

euchromatin - less condensed, expressed genes

heterochromatin - more condensed, silent/no genes

what is the nucleolus

site of rRNA synthesis, rRNA processing and assembly of ribosomal subunits

what can be said if there is a large nucleolus

it is typical of cells that produce large amounts of protein

what are ribosomes

made of rRNA and protein

carry out protein synthesis (translation)

high rate of protein synthesis = large numbers of ribosomes

where do proteins made in free ribosomes go

they function in the cytoplasm

where do proteins made in bound ribosomes go

they are either inserted into membranes/organelles or secreted