Foundations-Cells-5

From CellBiology

Compartments


This lecture is also an introduction to cell compartments and describes the structure of membranes forming these compartments.


Draft - this online lecture is currently in 2018 draft status. This notice removed when completed.
Cells and Membranes: 1 Cells and sizes | 2 Prokaryotes | 3 Viruses and prions | 4 Plasma membrane | 5 Compartments | 6 Membrane structure | 7 Membrane specialisations | Foundations - Moodle

Terms

  • biochemical process - chemical processes within and relating to living organisms.
  • chromosome territory - 3 dimensional region of the nucleus occupied by a specific chromosome.
  • compartment - a separate section region or part of a structure.
  • cytoskeleton - formed together by the 3 separate filaments systems (microfilaments, microtubules, and intermediate filaments) within cells. Note the nucleus only contains intermediate filaments.
  • DNA - Deoxyribonucleic acid the basic structure of our genes located in the nucleus and within mitochondria.
  • metabolic process - chemical processes/transformations required for survival of cells.
  • mitochondria -
  • nucleus -
  • nucleolus - functional compartment within the nucleus formed by a number of chromosomes and contains genes for the ribosome.
  • nuclear envelope - double membrane surrounding the nucleus.
  • nuclear pore - protein channel in the nuclear envelope that regulates transportation between the nucleus and the cytoplasm.
  • organelle - membrane enclosed compartment within a cell that has a specific function.
  • symbiotic - interaction between two different organisms living in close physical association. Note this is an theoretical evolutionary term for mitochondria, as they cannot today exist as a separate organism.
  • vesicles - general term for small membrane enclosed spaces within the cytoplasm.

Compartments

  • Physical Compartments - membrane bound
    • Nucleus, Cytoplasm, Organelles
    • cell nomenclature based upon presence or absence of these compartments (eukaryotic, prokaryotic).
  • Functional Compartments - not membrane bound
    • spatial localization for targeting, activation and inactivation, signaling.

Major Cellular Compartments

  • Nucleus (nuclear) - contains a single organelle compartment
  • Cytoplasm (cytoplasmic) - contains many organelle compartments

Organelle Number/Volume

  • How many organelles?
  • How much space within the cell do they occupy?
  • Are all the cells the same?

Take a typical mammalian liver cell....

Liver Structure


Table 12-1. Relative Volumes Occupied by the Major Intracellular Compartments in a Liver Cell (Hepatocyte)

Table 12-2. Relative Amounts of Membrane Types in Two Kinds of Eucaryotic Cells


Compartments are Dynamic - Movies showing flexibility of membranes and their changing shape and size.

Nuclear Compartment

Membrane evolution.jpg

Proposed model for nucleus organelle membrane evolution

Nucleus cartoon3.jpg

Nucleus cartoon

  • Nuclear envelope - a double membrane with pores passing through both membranes.
  • Nuclear matrix - consisting of Intermediate filaments (lamins)
  • Nucleoli (functional compartment - localised transcription DNA of RNA genes)
  • Chromosomes (DNA and associated proteins)

Note

  • there are no additional membrane compartments within the nucleus itself.
  • you will not see chromosomes in interphase cell nuclei (only during mitosis/meiosis).

Cytoplasmic Compartment

Mitochondria
  • Cytoplasmic Organelles - Membrane bound structures (Endoplasmic reticulum, golgi apparatus, mitochondria, lysosomes, peroxisomes, vesicles)
  • Cytoskeleton - 3 filament systems
  • Cytoplasmic “structures” - Ribosomes (translation)
  • Proteins - Receptors, signaling, metabolism, structural
  • Viruses, bacteria, prions


Functional compartments (you cannot see a membrane)

  • occur in nucleus, cytoplasm, in organelles and outside organelles
  • signaling, metabolic reactions, processing genetic information, cytoskeleton dynamics, vesicle dynamics



Draft - this online lecture is currently in 2018 draft status. This notice removed when completed.
Cells and Membranes: 1 Cells and sizes | 2 Prokaryotes | 3 Viruses and prions | 4 Plasma membrane | 5 Compartments | 6 Membrane structure | 7 Membrane specialisations | Foundations - Moodle