Unit 1- Into to Cell Biology

• The microscope was invented in 1950 by Hans Lippershey, Hans Janssen and Zacharias Janssen
• Robert Hooke wanted to see the structure of a wine cork under a microscope and saw the cell wall. He saw the cells and called them cellula
• Antonie Van Leeuwenhoek is known as the "Father of Biology" and worked with glass to improve the quality of lenses.
• Antonie Van Leeuwenhoek was the first to observe:

  • Single-celled protists
  • Bacteria from his mouth
  • Blood and muscle cells
• The first biologists used to have to draw everything by hand
• The compound microscope was developed in the 1830s. It improved magnification and resolution and it allowed visualization of very small objects
• The smallest we can see with the unaided eye is 0.2 mm
• Robert Brown in 1833 noticed that every cell contained a round structure that he called a kernel which is now known as a nucleus
• Matthias Schleiden in 1838 noticed that all plant tissues are composed of cells and embryonic plants always arise from a single cell (seed)
• Theodore Schwann in 1839 recognized structural similarities between plant and animal cells and formulated the cell theory
• The Cell Theory:

  • All organisms consist of one or more cells
  • The cell is the basic unit of structure for all organisms
  • All cells arise from pre-existing cells
• A fact is something that has occurred or is true
• A scientific fact is an attempt to state our best current understanding and is valid until revised or replaced by a better understanding
• Biologists are very conservative about using the term law as it cannot be changed
• Eukaryotes contain a combination of genomes that originally derive from archaea and bacteria
• All cells come from one common ansestor
• Transmission electron microscopy is used to look at atoms when a higher magnification is needed to look at atoms
• Scanning electron microscopy is used to scan the surface of a sample to determine the size of the sample
• Basic Properties of all Cells

  • Highly complex and well organized
  • Acquire and use energy (bioenergetics)
  • Use the same genetic program, central dogma
• Size of genetic components

  1. Atoms
  2. Molecules
  3. Macromolecules
  4. Organelles
• The central dogma is the cycle for how all genetic information is present and replicated with protein being the end product
• Life is an autocatalytic process and not all cells survive as some go through apoptosis
• Cells:

  • Have many processes that are highly conserved at the molecular level
  • Engage in many mechanical activities
  • Respond to environmental signals
  • Are capable of self-regulation, homeostasis
• Prokaryotes:

  • Have no nucleus
  • Include eubacteria and archarbacteria
• Eukaryotes:

  • Have a true nucleus
  • Surrounded by a nuclear membrane
  • Include protists, fungi, plants and animals
• The three major divisions in the genome sequence comparison are bacteria, archaea and eukaryotes
• Prokaryotes are the most diverse cell group as they can form different sizes, shapes and arrangements. They also have a short doubling time
• The two domains of prokaryotes are:

  1. eubacteria
  2. They all have cell walls except mycoplasma
  3. archaebacteria
  4. All have cell walls
  5. Can survive in extreme environment
• Four groups of Eukaryotes:

  1. Protists
  2. Very diverse group
  3. Mostly single-celled but some colonies
  4. Includes things like algae, water molds, slime molds and protozoa
  5. Fungi
  6. Singel cells (yeasts) and multicellular (mushrooms)
  7. Have cell walls
  8. Are heterotrophs and need energy from outside sources
  9. Plants
  10. Multicellular
  11. Have cell walls
  12. Are autotrophs and can get their own energy through photosynthesis
  13. Animals
  14. Multicellular
  15. No cell wall
  16. Heterotrophs
• Compartmentalization in Eukaryotic Cells:

  • Cytoplasm
  • Everything that is between the plasma membrane and nuclear membrane
  • Includes all membrane-bound organelles except the nucleus
  • Cytosol
  • Only fluid component in the cell
  • Endomembrane system
  • Internal membranes that are either in direct contact or connected via transfer of vesicles
• Structures within Eukaryotic cells:

  • Membrane-bound compartments
  • Nucleus- stores chromosomes
  • Endomembrane system
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosomes
  • Organelles with own genome
  • Mitochondria- generates energy to power the cell
  • Chloroplasts- uses energy from sunlight, converts CO2 to carbohydrate
  • Cytoskeleton- regulates the shape, movement of material and movement of the cell itself
• Secretory Pathway:

  • Rough endoplasmic reticilum
  • Synthesis of protein for export, insertion into membranes and lysosomes
  • Golgi apparatus
  • Collection, packaging and distribution
• The mitochondria and chloroplasts contain DNA that encodes some of their own proteins and have double layers of membranes
• Endosymbiont Theory is when 2 things come together to make something better for survival
• It is accepted that early eukaryotes originated as predators and certain organelles evolved from smaller prokaryotes engulfed by larger cell
• Advantage of symbiosis to the host cell:

  • Aerobic respiration
  • Photosynthesis
• Advantage of symbiosis to bacteria:

  • Protected environment
  • Supply of carbon compounds from host cell's other prey
• The organization within eukaryotic cells is not random
• The cytoskeleton is important in:

  • Cell shape
  • Cell mobility
  • Movement/position of organelles
  • Movement of materials within the cell
  • Movement of chromosomes during mitosis
• Prokaryotes:

  • Have no nucleus
  • Have no membrane bound organelles
  • Most have a cell wall
  • Are very small and have no need for a cytoskeletal transport system
  • Smaller than eukaryotic cells'