BIOL2200 Lecture Notes - Lecture 10: Cardiomyopathy, Eukaryotic Small Ribosomal Subunit (40S), Progeroid Syndromes
CELL MACHINERY LEC 2 BIOL2200
Lecture 2: Nucleus
The nucleus
oLarge organelle (easily visible under light microscope)
oThe 'brain' or 'hard drive' of the cell. DNA within encodes the majority (but not all)
proteins within a cell
oGene expression (transcription) determines the nature of the cell/organism
oComplex organisation: out focus today nuclear envelope, nucleolus, and nuclear
pore
oHighly dynamic (eg. Dramatic restructure for mitosis)
Nuclear architecture
oNuclear membrane
Nucleus is surrounded by two membranes + nuclear lamina = nuclear
envelope
Inner nuclear membrane (INM) defines nucleus
Outer nuclear membrane (ONM) continuous with rough endoplasmic
reticulum
INM and ONM are each phospholipid bilayers separated by perinuclear
space
oNuclear lamina
Nuclear envelope is supported basally by the nuclear lamina
Meshwork of filaments located adjacent to the inside face of the inner
nuclear membrane
Comprised of a class of cytoskeletal proteins known as intermediate
filaments (nuclear Lamins)
Cage or lattice-like network that interconnects with nuclear pores
Provides nucleus with structure
oNucleolus/nucleoli phase separate - only found this out 3-4 years ago
A sub-organelle and clearly defined structure within the nucleoplasm
Unlike nucleus, has no membrane!
Site of ribosome biogenesis
Formed around regions of DNA encoding ribosomal RNA (rRNA)
Specifically tandem repeated clusters of rRNA genes - Nucleolar Organiser
Regions (NOR)
Hotspot of transcriptional activity (~80% of total RNA in cell is rRNA)
Thus, nucleoli are genetically defined structures formed as a result of
making ribosomes
oNuclear bodies
Membraneless nuclear sub-compartments
Highly dynamic in nature and in constant flux
In most cases, concentrated regions of protein and RNA (ribonucleoprotein
complexes)
Formation associated with transcriptional and RNA processing activity
Generally speaking, their formation may enhance process efficiency and
facilitate regulation
oChromatin
DNA+histone complex: nucleosome
Packaging of over 2m of DNA within nucleus
Chromatin structure is dynamic (extended/condensed)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
The "brain" or "hard drive" of the cell. Dna within encodes the majority (but not all) proteins within a cell: gene expression (transcription) determines the nature of the cell/organism o. Complex organisation: out focus today nuclear envelope, nucleolus, and nuclear pore: highly dynamic (eg. dramatic restructure for mitosis) Nucleus is surrounded by two membranes + nuclear lamina = nuclear envelope. Outer nuclear membrane (onm) continuous with rough endoplasmic reticulum. Inm and onm are each phospholipid bilayers separated by perinuclear space: nuclear lamina. Nuclear envelope is supported basally by the nuclear lamina. Meshwork of filaments located adjacent to the inside face of the inner nuclear membrane. Comprised of a class of cytoskeletal proteins known as intermediate filaments (nuclear lamins) Cage or lattice-like network that interconnects with nuclear pores. Provides nucleus with structure: nucleolus/nucleoli phase separate - only found this out 3-4 years ago. A sub-organelle and clearly defined structure within the nucleoplasm. Formed around regions of dna encoding ribosomal rna (rrna)
