Ib Biology Cell Theory

Topics: Cell, Cellular differentiation, DNA Pages: 4 (1232 words) Published: February 3, 2013
2.1 Cell Theory
2.1.1 Outline the cell theory
The three main principles of the cell theory are:
* All organisms are composed of one or more cells
* Cells are the smallest units of life
* All cells come from pre-existing cells
New Concepts
* Cells contain the blueprint for their own growth, development and behavior * Cells are the site of all the chemical reactions needed to sustain life * Cells (and multicellular organisms) show emergent properties – appears as complexity increases

2.1.2 discuss the evidence for the cell theory
* Largely through the use of the microscope. Robert Hooke first described cells in 1665 while observing cork with a microscope he built himself. * Then Anotnir van Leeuwenhoek observed the first living cells and referred to them as ‘animalcules.’ Meaning little animals * 1838, Mathias Schleiden states that plants are made of independent, separate beings called cells * 1839, Zoologist Theordor Schwann made a similar statement about animals * Even today, we have not been able to find any living entity that is not made up of at least one cell

2.1.3 State that unicellular organisms carry out all the functions of life All organisms exist in either a unicellular or a multicellular form. All organisms carry out all the functions of life. These functions include: * Metabolism

* Growth
* Reproduction
* Response
* Homeostasis
* Nutrition
All these are tied together to produce a functioning living unit * Metabolism includes all the chemical reactions that occur within an organism * Growth may be limited but is always evident in oen way or another * Reproduction involved heredity molecules that can be passed to offspring * Response to the environment is imperative to the survival of the organism * Homeostasis refers to maining a constant internal environment such as temperature * Nutrition is about providing a source of compounds with many chemical bonds...
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