Cell Theory


2.1.1 Outline the Cell Theory


1. All living things are made up of cells.
2. The cell is the smallest form or unit of life.
3. All cells come from pre-existing cells.

2.1.2 Discuss the evidence for the cell theory


Like any theory, cell theory is only based on previous observations and facts. It is an accepted theory because it is supported by evidence gathered by many (although it would be imposssible to observe every known living and non living thing). A few scientists involved in the establishment of cell theory, and their discoveries:
1600s--Anton van Leeuwenhoek looks at a drop of pond water under a primitive microscope and observes microscopic and single celled organisms.
1665--Robert Hooke discovers cells by looking at a piece of cork (made from tree bark) under a primitive microscope. He noticed the cell walls of the dead plant tissue.
1839--Theodor Schwann notes that the cells of animals and plants are very alike in structure.
This evidence supports the first tenet of cell theory, that all organic matter is made up of cells.

1839--Matthias Schleiden observes that a plant embryo would grow from a single cell, and that all the tissues of the plant are made of cells.
1855--Rudolph Virchow observes that unusual events in the body occured when there was irregular cellular activity.
This evidence support the tenet of cell theory that all cells come from pre-existing cells (by division).


2.1.3 State how unicellular orgaisms carry out all the functions of life


Unicellular organisms can carry out all the functions that multi cellular beings such as humans carry out.
All living things: reproduce, utilize a form of metabolism (take in/use energy), homeostasis, excretion, growth.

2.1.4 Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using the appropriate SI unit

2.1.5 Calculate the linear magnification of drawings and the actual size of speciemenes in images of known magnification.

2.1.6 Explain the importance of the surface area to volume ratio as a factor limiting cell size.

2.1.7 State that multicellular orgainsms show emergent properties

2.1.8 Explain that cells in multicelular organisms differentiate to carry out specialized functions by expressing some of their genes but not others.

2.1.9 State that stem cells retain the capacity to divide and have the ability to differentiate along different pathways.

2.1.10 Outline one therapeutic use of stem cells.