文档介绍：“Principles of Radiation Interactions”
Overview of Cell Biology
The Cell
• Cells are the fundamental unit of life; the structural and functional unit of all
anisms.
• The cell theory: anisms posed of cells and all e from
pre-existing cells.
• In single-anisms such as bacteria and protozoa, each cell is
independent.
• In multi-anisms, function is distributed among different specialized
cells.
• Cells to tissues ans anisms…
• Biological systems use cells to build higher levels anization, but the cell
remains the fundamental unit. Radiation effects at the cellular level can affect
the higher-anization.
[Image removed due to copyright considerations]
[Lodish, 2000]
Overview of Cell Biology Page 1 of 30
“Principles of Radiation Interactions”
What can cells do?
Cells can:
• use DNA as hereditary material,
• use proteins as catalysts
• reproduce
• transform matter and energy
• respond to their environment
Sizes and shapes vary
µm bacteria to a several cm hen egg (yolk)
shapes can be spherical, flattened columnar, cuboidal.
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“Principles of Radiation Interactions”
The cell membrane
• The interior of cells is an aqueous environment.
• Most of the intracellular molecules are water-soluble.
• Most of the chemical reactions carried out inside cells require an aqueous
environment.
• The environment around cells is also basically an aqueous one.
• Bodily fluids and blood are aqueous solutions of proteins and small
molecules.
• Chemically (pH, ionic strength) blood is similar to sea water.
For cells to maintain integrity they must be surrounded by a membrane through
which water cannot flow. A posed of fatty acid molecules served
this purpose.
All cells have a cell membrane, a two-layered shell of phospholipids. All
biological membranes have the same basic phospholipid bilay