General biology

• In 1838, German botanist Matthias Schleiden concluded that all plants are made of cells. The next year, another German scientist, Theodor Schwann, concluded that animals are also made up of cells. Rudolf Virchow, a German physician, studied cell reproduction. In 1855, he summarized years of research by stating, “Where a cell exists, there must have been a preexisting cell.”
• German botanist Matthias Schleiden concluded that all plants are made of cells in 1838.
• German scientist, Theodor Schwann, concluded that animals are also made up of cells
• The cell theory states the following: a. All living things are composed of cells. b. Cells are the basic units of structure and function in living things. c. New cells are produced from existing cells.
• Microscopes are devices that produced magnified images of structures that are too small to see with the unaided eye
• Electron microscopes produced magnified images by focusing beams of electrons
• Light microscopes produced magnified images by focusing visible light rays.
• Electron microscopes

  can form images of objects 1000 times smaller than those visible under a light microscope.
• Plasma Membrane

  -Separates cell from external environment; controls passage of organic molecules, ions, water, oxygen and wastes into and out of the cell.
• Cytoplasm

  -Provides structure to cell; site of many metabolic reactions; medium in which organelles are found.
• Nucleoid

  -Location of DNA
• Nucleus

  -Cell organelle that houses DNA and directs synthesis of ribosomes and proteins
• Ribosomes

  -Protein synthesis
• Mitochondria

  -ATP production or cellular respiration
• Peroxisomes

  -Oxidizes and breaks down fatty acids and amino acids and detoxifies poisons
• Vesicles and Vacuoles

  -Storage and transport; digestive function in plant cells
• Centrosome

  -Unspecified role in cell division in animal cells; organizing center of microtubules in animal cells
• Lysosomes

  -Digestion of macromolecules; recycling or worn out organelles
• Cell Wall

  -Protection, structural support and maintenance of cell shape
• Chloroplast

  -Photosynthesis
• Endoplasmic reticulum

  -Modifies proteins and synthesizes lipids
• Golgi apparatus

  -Modifies, sorts, tags, packages and distributes lipids and proteins
• Cytoskeleton

  -Maintains cells’ shape, secure organelles on specific positions, allows cytoplasm and vesicles to move within the cell, and enables unicellular organisms to move independently
• Flagella

  -Cellular locomotion
• Cilia

  -Cellular locomotion, movement of particles along extracellular surface of plasma membrane, and filtration