- A cell is completely contained within a plasma membrane. This membrane keeps all
of the cell's contents neatly inside, while keeping out harmful substances. Inside the cell
are the cytoplasm, the nucleus, and the organelles-structures that perform various
functions.
- The cytoplasm is a gel-like substance in which the nucleus and organelles are found.
- The nucleus is the “brain” of the cell. It contains the genetic information in the form of
chromosomes (structures that contain our genes), as well as the nucleolus, a structure
that helps the nucleus function. The nucleus is completely separated from the rest of the
cell by a membrane similar to the plasma membrane that encircles the cell.
- Each of the organelles (various cell structures) has a different function, but they all
work to keep the cell healthy and help it perform its job.
- Outside of the cell is the extracellular membrane – more about this later.
Cell Biology
Cell biology is an academic discipline that studies cells - their physiological properties,
their structure, their interactions with their environment, their life cycle, division and
death. This is done both on a microscopic and molecular level. Cell biology research
encompasses both the great diversity of single-celled organisms like bacteria and
protozoa, as well as the many specialized cells in multicellular organisms like humans.
Knowing the components of cells and how cells work is fundamental to all biological
sciences. Appreciating the similarities and differences between cell types is particularly
important to the fields of cell and molecular biology as well as to biomedical fields such
as cancer research and developmental biology.
"A cell's genetic material, its DNA, is found in its nucleus and includes a complete set of
chromosomes (46 chromosomes). This genetic material controls everything the cell does
including how it proceeds through the cell cycle." Quote from WikiGenetics created by
Genetic Alliance"
Normal Cell Communication:
Normal cells act on each other to control their growth and other properties in balance
with the entire organism. They are closely regulated by a variety of genetic and
biochemical signaling processes.
Image courtesy of Dr. Roadnottaken of the Scripps Institute:
This is for reference purposes only to illustrate
the complexity of the normal cell communication networks.
For example, biological feedbacks act in much the same way that a thermostat controls
heat production by a furnace. Cancer is a disease of “outlaw” cells, cells that have lost
their normal relationship to the whole organism so that this feedback loop is damaged.
Crucial to all normal cell growth is a communication network that functions properly. This
network is an intricate collection of pathways built with interactive proteins. Along these
pathways, precise protein-to-protein signaling enables a very carefully guarded
regulation of growth and function. Cell signaling is part of a complex system of
communication that governs basic cellular activities and coordinates cell actions.
The ability of cells to perceive and correctly respond to their internal signals as well as to
their microenvironment is the basis of development, tissue repair, and immunity as well
as normal tissue health. Errors in cellular information processing are responsible for
diseases such as cancer, autoimmunity, and diabetes. By understanding cell signaling,
diseases may be treated effectively and, theoretically, artificial tissues may be yielded.
In biology, the term crosstalk refers to the phenomenon that signal components
in one signal pathway can be shared between different signal pathways and responses
to a signal inducing condition (e.g., stress) can activate multiple responses in the
cell/organism.
Traditional work in biology has focused on studying individual parts of cell signaling
pathways. Systems biology research helps us to understand the underlying structure of
cell signaling networks and how changes in these networks may affect the transmission
and flow of information. Such networks are complex systems in their organization and
function.
Analysis of cell signaling networks requires a combination of experimental and theoretical
approaches including the development and analysis of simulations and modeling.
Cancer is a Communication Failure in the cell
The genetic changes involved in cancer result in altered proteins that disrupt the cell’s
communication network. In cancer, altered proteins along many different pathways cause>
signals to be garbled, intercepted, amplified, or misdirected
These changes hijack what was once normal communication and use it to achieve
uncontrolled tumor growth. The image below illustrates some examples of how cancer
disrupts normal cellular pathways.
Image courtesy of the National Cancer Institute for reference purposes only
CISN Summary
- Each individual cell has an internal signaling network along extensive pathways.
- Cells communicate with one another by means of chemical signals.
- When either internal or cell-to-cell communication is damaged disease may occur
including cancer.
