An Outline of the Cell Theory
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 observed the 1st living cells and referred to them as animalcules. “microscope” • In 1838, botanist Mathias Schleiden stated that plants are made of independent separate being called cells. Later, Theoder Schwann made a similar statement about animals. • The 2nd principle continues to gain support because we have not been able to find any living entity that is not made of at least one cell. • Louis Pasteur in the 1860s performed experiments to support the last principle. After sterilizing chicken broth by boiling, Pasteur showed that living organisms would not ‘spontaneously’ reappear. “biogenesis” • Only after exposure to preexisting cells was life able to re-establish itself in the chicken broth. • Eukaryotes- mitosis; prokaryotes- binary fission; thus all cells have a common ancestor- original ancestral form 2.1.3 State that unicellular organisms carry out all the functions of life (1). • Functions include:
• Metabolism- chemical reactions that occur within an organism • Growth- may be limited but is always evident in some way • Reproduction- hereditary molecules that can be passed to offspring • Response- to environment is imperative to survival
• Homeostasis- maintain a constant internal environment ex: temp • Nutrition-
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 observed the 1st living cells and referred to them as animalcules. “microscope” • In 1838, botanist Mathias Schleiden stated that plants are made of independent separate being called cells. Later, Theoder Schwann made a similar statement about animals. • The 2nd principle continues to gain support because we have not been able to find any living entity that is not made of at least one cell. • Louis Pasteur in the 1860s performed experiments to support the last principle. After sterilizing chicken broth by boiling, Pasteur showed that living organisms would not ‘spontaneously’ reappear. “biogenesis” • Only after exposure to preexisting cells was life able to re-establish itself in the chicken broth. • Eukaryotes- mitosis; prokaryotes- binary fission; thus all cells have a common ancestor- original ancestral form 2.1.3 State that unicellular organisms carry out all the functions of life (1). • Functions include:
• Metabolism- chemical reactions that occur within an organism • Growth- may be limited but is always evident in some way • Reproduction- hereditary molecules that can be passed to offspring • Response- to environment is imperative to survival
• Homeostasis- maintain a constant internal environment ex: temp • Nutrition-