BIOL 1001 Chapter : Chapter4 Part 1
Chapter 4 part I
• Robert hook
o Invented primitive microscope
o Observed “little boxes” = cells (in cork)
o Discovered similar structures in live plants
• Leeuwenhoek
o Discovered “animalcules” in water samples
▪ Mostly single-celled organisms
o Observed blood, sperm, microscopic eggs
▪ Countered idea of spontaneous generation
▪ Fleas believed to emerge from dust
• Light microscopy
o Most commonly used
o Light used to illuminate specimen
o Combination of lenses magnify and focus image
o Stains often used to provide contrast
Electron Microscopy
▪ Beams of electrons replace loight
▪ Magnetic fields focus image
▪ Transmission Electron Microscopy
o Electron passed through specimen
o Intrerior details of cell visible
▪ Scanning Electron Microscopy
o Electrons bounced off specimen
o 3-D image produced
The cell theory
▪ Developed in 1855
▪ 3 Prinicpals
o Every living organism is made up of 1 or more cells
o Smallest living organisms are single cells and cell are functional units of
multicellular organisms
▪ Cells = basic unit of life
o Cells arise from pre existing cells
Cells
▪ Must obtain energy and nutrients
▪ Must eliminate waste
▪ Must synthesize proteins and other molecules
▪ Must reproduce
▪ Many interact with other cells
Common Features of Cells
▪ Small in size
o 1-100 micrometers (um)
o Aids in nutrient and wast exchange with external environment
▪ All have
o Plasma membrane
o Cytoplasm
o DNA & RNA
Plasma Membrane
▪ Thin, fluid membrane that encloses cell
o Phospholipid bilayer with embedded proteins
▪ Functions
o Isolates cell contents from external environment
o Regulates flow of materials in and out of cell
o Allows for cellular interactions with
▪ Other cells
▪ Environment
Phospholipid bylayer
▪ Hydrophilic head (water loving)
o Faces water intracellular and extracellular environments
▪ Hydrophobic tail (water fearing)
o Faces interior of membrane
▪ Maintains differences in concentrations of materials inside and out of cell
o Allows oxygen, carbon dioxide, and water to move in and out easily
o Barrier to most hydrophilic molecules and ions
FIGURE 5.3
LEFT: Bilayer
RIGHT: 1.Hydrophilic heads
Document Summary
Invented primitive microscope: observed little boxes = cells (in cork, discovered similar structures in live plants. Discovered animalcules in water samples: mostly single-celled organisms, observed blood, sperm, microscopic eggs, countered idea of spontaneous generation, fleas believed to emerge from dust. Light microscopy: most commonly used, light used to illuminate specimen, combination of lenses magnify and focus image, stains often used to provide contrast. Electron microscopy: beams of electrons replace loight, magnetic fields focus image, transmission electron microscopy, electron passed through specimen. Intrerior details of cell visible: scanning electron microscopy, electrons bounced off specimen, 3-d image produced. Cells: must obtain energy and nutrients, must eliminate waste, must synthesize proteins and other molecules, must reproduce, many interact with other cells. 1-100 micrometers (um: aids in nutrient and wast exchange with external environment, all have. Regulates flow of materials in and out of cell.
