Cell Theory Overview

Study Notes

Cell – basic unit of life, involves all processes to sustain life
Organelles – sub-cellular components of cells
Levels of Cells
- Tissue – group of similar cells
- Organs – group of different tissues with specific functions
- Organ System – organs working together
- Organism – biological product composed of cells, tissues, and organs
Theory of Spontaneous Generation – living things arise from non-living matter; disproven
Scientists
- Francisco Redi – disproved spontaneous generation through experiment
- Robert Hooke – coined the term "cell"
- Antonie van Leeuwenhoek – discovered micro-organisms (animalcules)
- Matthias Schleiden – discovered plant cells
- Theodor Schwann – discovered animal cells
- Rudolf Virchow – proposed that cells come from other cells (omnis cellula e cellula)
Cell Theory
- Organisms composed of one or more cells
- Cell is the basic unit of life, performing life processes
- Cells come from pre-existing cells
- Contains Deoxyribonucleic Acid (hereditary information passed during cell division)
- Same chemical composition and metabolic activities

Cell Membrane – controls substance entry/exit; separates internal/external environment; composed of water, salts, enzymes
Cytoplasm – jelly-like substance; medium for reactions
Nucleus – houses genetic material; contains pores
Ribosomes – synthesize proteins
Endoplasmic Reticulum – processes, and transports new materials
- Rough ER synthesizes proteins
- Smooth ER synthesizes lipids
Golgi Apparatus – processes, modifies, and packages proteins and lipids
Mitochondria – energy-producing organelles; produce Adenosine Triphosphate (ATP)
Cytoskeleton – structural support; maintains cell shape; moves and transports cell components
Vacuoles – storage and transport
Cell Wall (plants) – rigid wall made of cellulose, pectin, and hemicellulose; provides support
Chloroplasts (plants) – responsible for photosynthesis; contain chlorophyll to convert solar to chemical energy, produces oxygen and glucose
Lysosomes– membrane-bound organelles with digestive enzymes, break down waste materials and cellular debris

Prokaryotes:
- "Pro" – before; "Karyo" – nucleus
- Lack a true nucleus and membrane-bound organelles
- Example: Archaea and Bacteria
Eukaryotes:
- "Eu" – true; "Karyo" – nucleus
- Have a nucleus and membrane-bound organelles
- Examples: Fungi, Animals, Plants

Organisms reproduce and have heredity; variation exists among offspring
Genetics is studying heredity and variation
Life continuity is dependent on reproduction and division of cells
Cell division means new cells arise from pre-existing cells; multicellular organisms originate from a zygote