An Outline of the Cell Theory Essay

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Chapter 2 IB Biology
2.1 Cell Theory
2.1.1 Outline the cell theory (2).
• All organisms are composed of one or more cells
• Cells are the smallest units of life
• All cells come from preexisting cells
• TOK: cell theory replaces the former ideas of spontaneous generation or abiogenesis in which inanimate matter assembles itself into living forms • Exception: muscle cells- more than 1 nucleus, very long; (fungal cells) hyphae roots- not a single unit; protoctista- not specialized to single function; subcellular things like organelles 2.1.2 Discuss the evidence for the cell theory (3).
• Robert Hooke first described cells in 1665 while observing cork with a microscope he built. Coined the term “cell” • Antoine van Leeuwenhoek
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• As organisms grow, cells divide. 2 small cells are more efficient than one. • Alveoli in lungs maximize surface for gas exchange.
2.1.7 State that multicellular organisms show emergent properties (1). • Different things come together to make process
• Cells-tissues-organs-etc.
• Ability to reproduce themselves. Allows possibility of growth and for replacement of damaged or dead cells. 2.1.8 Explain that cells in multicellular organisms differentiate to carry out specialized functions by expressing some of their genes but not others (3). • Start out as single cell that reproduces at a rapid rate then the resulting cells go through a differentiation (different cells- different functions- to run an organism) process to produce all required cell types that are necessary for organism. • Every cell in a multicellular organism contains all the genes of that organism. However, the genes that are activated vary from cell to cell. • Differentiation- when we break something complex into its component pieces, they each appear to be simple. Combined, they can perform a whole new function. Cells within a multi cellular organism specialize their function. • Examples: muscles cells, cardiac cells
• This differentiation process is the result of the expression of certain specific genes but not others • Genes allow for the production of all different cells in the organism • Each cell contains all the genetic info for the production of the complete organism • Each
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