Cell Theory Overview

Cell Theory

• 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 Structure

• 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 and Eukaryotes

• 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

Cell Cycle

• 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

Explore the fundamental concepts of Cell Theory, including the structure and function of cells, organelles, and the hierarchy of biological organization. Learn about key scientists who contributed to our understanding of cells and the disproval of spontaneous generation. Test your knowledge on these essential topics in biology.