(For the most accurate definitions of words, there will be links to the textbook/review guide definition in my notes.)3.1 The Cellular Level of Organization
Cell Theory
What is the cell theory?
Summarized as:
1) All living organisms are made up of one or more cells
2) The cell is the basic unit of life
3) All cells come from division of pre-existing cells
Key People mentioned:
Robert Hooke: first to use the term “cell” Antonie van Leeuwenhoek: discovered microscopic animals in water Matthias Schleiden and Theodore Schwann: discovered organisms are made of cells (plant and animals) Rudolph Virchow: stated that cells come from division of pre-existing cells |
What is a cell?
-structural and functional until of an organism; the smallest structure capable of preforming necessary for life.
Microscopy
-Cytology is the study of cells
Three types of microscopes used:
Compound Light Microscope:
-1000x magnification
Transmission Electron Microscope:
-transmit beam of electrons through specimen
-30 000x magnification
The major disadvantage of the transmission electron microscope is the need for extremely thin sections of the specimens, typically about 100 nanometers. Biological specimens typically require to be chemically fixed, dehydrated and embedded in a polymer resin to stabilize them sufficiently to allow ultrathin sectioning. (wiki)
Scanning Electron Microscope:
-scans with beams of electrons
-3-D images (however specimen must be dead -- like Transmission Electron Microscope)
Importance of Cell Size
-measured in micrometers (μm)
-Nutrients enter a cell and dispels waste at its surface (meaning the more surface area the better ability to get material in and out of cell
-(volume represents needs of cell)The larger the cell = requires more nutrients and produces more waste than a small cell
-The larger the volume, the smaller surface area there is.
WHY?
SMALL BOX:
Surface area: (are of a “face-side” x 6 (there are 6 sides in a box)
1mm x 1mm x 6mm= 6mm2
Volume= l x w x h
1mm x 1mm x 1mm= 1mm3
Surface Area: Volume
6:1BIG BOX:
Surface area: (are of a “face-side” x 6 (there are 6 sides in a box)
2mm x 2mm x 6mm= 24mm2
Volume= l x w x h
2mm x 2mm x 2mm= 8mm3
Surface Area: Volume
24:8 = 3:1
-relies on cell diffusion to get materials in and out of cell. When the cell is too large, metabolic wastes cannot get out fast enough = build up of toxicity level = cell dies.
How do cells get past Surface Area limitations?
-Divide
-Slow down metabolism
-Become long/thin (example: nerve cells)
- Folds in cell membrane (folds create more surface area like in microvilli of intestinal epithelial cells)
Other/Final Things:
Disclaimer: These are my personal notes after reading the textbook/review guide and by no means are these all correct (although I try to make the information as accurate as possible).
If anyone has info to add or if anything is incorrect please inform me, I would appreciate that :].
No comments:
Post a Comment