CELL

• Robert Hooke

  In 1665, an English scientist examined a thin slice of cork under the microscope and observed that the piece of cork was composed of many tiny compartments that resembled little rooms with surrounding walls. Hooke named this compartment cells.
• Anton van Leeuwenhoek


  In 1674, the Dutch inventor observed the RBC, sperm cells, and a multitude of single-celled organisms in pond water. He discovered free cells and observed the nucleus within some RBC. He also discovered bacteria, free living and parasitic protists, and other microscopic organisms.
• Robert Brown


  Scottish Botanist, in 1831 he discovered nucleus and theorized that this structure is a fundamental and constant component of the cell. He also discovered Brownian Movement, the random movement of minute particles of matter suspended in a fluid.
• Felix Dujardin


  French Biologist, in 1835 he found out that living cells contain an internal substance and gave it the name sarcode.
• Jan Evangelista Purkinje


  Bohemian Physiologist made a thorough investigation of the internal material (sarcode) and gave it the name protoplasm, the colloidal substance in the cell.
• Matthias Schleiden


  German Botanist, in 1838 stated that all plants are composed of cells.
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  Theodor Schwann - German Zoologist, in 1839 concluded that all animals are composed of cells.
• Rudolf Virchow


  German Biologist, in 1858 he theorized that all living cells come from preexisting living cells. His conclusion arose from observing dividing cells during his work.
• Cell Theory

  • All living things are composed of one or more cells and cell products.
  • All living cells come from other living cells by the process of cell division.
  • Cells are the basic unit of structure and function in organisms.
• Cell Functions

  • Nutrition
  • Digestion
  • Absorption
  • Biosynthesis
  • Excretion
  • Egestion
  • Secretion
  • Movement
  • Irritability
  • Respiration
  • Cellular reproduction
• Cell


  The smallest unit of life that can function independently
• Most cells are too small to see without a microscope
• Transmission electron microscope


  A very powerful tool for seeing internal cell structures
• Scanning electron microscope


  A very powerful tool that reveals details on cell surfaces
• Light microscopes


  Less powerful than electron microscopes, they generate color images of living cells
• Smaller cells


  Have more surface area relative to their volume, allowing the cell to quickly exchange materials with its surroundings
• All Cells Have Features in Common

  • DNA
  • RNA
  • Ribosomes
  • Proteins
  • Cytosol
  • Cell membrane
• Different Cell Types Characterize Life's Three Domains

  • Prokaryotes (lack a nucleus)
  • Eukaryotes (have cells with a nucleus and other membranous organelles)
• Parts of a Cell

  • The cell membrane
  • The protoplasm and its organelles
  • The nucleus (in eukaryotes)
• Cell Membrane


  A thin layer that surrounds and protects all cells and their protoplasmic contents, composed of a double layer of phospholipid molecules with embedded protein molecules
• Protoplasm


  A colorless or somewhat grayish, translucent, viscous substance that is capable of flowing, composed of 20% C, 10% H, 62% N, and 5% trace elements
• Cytoplasm


  The protoplasm lying outside the nucleus, a clear thick fluid containing structures called organelles
• Karyoplasm or Nucleoplasm


  The protoplasm inside the nucleus
• Organelles suspended in the cytoplasm

  • Mitochondria
  • Ribosomes
  • Endoplasmic Reticulum
  • Golgi Bodies
  • Vacuoles
  • Lysosomes
  • Centrosomes
  • Centrioles
  • Cytoskeleton
  • Cell wall (in plant cells)
  • Plastids (in plant cells)
• Mitochondria


  Microscopic rod-shaped bodies in the cytoplasm that are the center of respiration of the cell and release energy for cell functions
• Ribosomes


  Tiny spherical bodies that help make proteins, found in the cytoplasm or attached to the endoplasmic reticulum
• Endoplasmic Reticulum (ER)


  A system of membranes throughout the cytoplasm that connects the nuclear membrane to the cell membrane and serves as a passageway for material moving through the cell
• Golgi Bodies

  Tube-like structures with tiny sacs at their ends that help package protein
• Vacuoles


  Clear fluid sacs that act as storage areas for food, minerals, and waste, larger in plant cells and smaller in animal cells
• Lysosomes


  Small structures that contain enzymes used in digestion, sometimes called "suicide sacs" because if the membrane is damaged they can destroy the entire cell
• Centrosomes and Centrioles


  Centrosomes are a mass of dense protoplasm with centrioles at the center, which duplicate and form spindle fibers during cell division
• Cytoskeleton


  The framework of the cell
• Lysosomes


  Small structures that contain enzymes which are used in digestion
• Lysosomes were discovered only in 1952
• Lysosomes


  • Rich in strong hydrolytic enzymes kept intact by a thick lysosomal membrane
  • Enzymes are capable of breaking down and destroying a number of important cellular constituents
  • Once the membrane is damaged, the lysosome releases its contents into the cytoplasm and may destroy the entire cell
• Centrosome


  A mass of dense protoplasm with structures called centrioles at the center
• Centrioles


  • As part of the cytoplasm, they duplicate and form at the center for spindle fiber formation during cell division
• Cytoskeleton


  A cellular framework that supports the internal system of a cell and gives the cell its shape

  
• The cytoskeleton is a complex network of microtubules and protein structures
• Cell Wall (Plant Cells Only)

  A non-living structure that surrounds the plant cell, protects and supports the cell, made up of a tough fiber called cellulose