Chapter 4- A View of the Cell

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Chapter 4-A View of the Cell
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4.1-The Discovery of Cells

• Cells are the basic units of living organisms
• Development of the microscope allowed scientists
  to view cells

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Cell Theory

• 1665-Robert Hooke
• Uses compound microscope to observe cork
• Hollow boxes..CELLS!!
• 1830s-Schleiden and Schwann
• Schleiden-all plants are composed of cells!
• Schwann-all animals are composed of cells!

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Three Parts of Cell Theory

• 1. All organisms composed of one or more cells.
• 2. Cell is the basic unit of organization of
  organisms.
• 3. All cells come from preexisting cells.

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History of the Microscope

• 1665-Hookes Microscope
• Three lenses
• Poor Quality
• Little detail

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• 1700-Anton van Leeuwenhoek
• Built over 240 microscopes!
• Single Lens
• Better Quality
• Observed red blood cells bacteria
• Mid 1800s-Compound Light Microscope
• Series of lenses
• Light passes through object then lens
• More detail

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• 1940s-Electron Microscopes
• Beam of electrons through magnetic field
• Specimen in vacuum
• Only view dead cells or organisms
• 1.SEM-Scanning Electron Microscope
• Surface of specimen-3D Picture!
• 2.TEM-Transmission Electron Microscope
• Through the specimen
• Magnify 100s or 1,000s of times!
• 3.STM-Scanning Tunneling Microscope
• Arrangement of atoms on surface
• Map hills and valleys

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Basic Cell Types

• Look at internal organization!
• Prokaryotes-lacks internal structures
• Eukaryotes-membrane bound, internal structures.
• Structures called organelles
• Largest organelle NUCLEUS!

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Section 4.2-Eukaryotic Cell Structure

• Must have boundaries!
• Plasma Membrane
• Boundary between cell environment
• Flexibility
• Controls movement of materials
• Cell Wall-only plant cells!
• Rigid, surrounds membrane
• Thicker, stronger network for structural support

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Fluid-Mosaic Membrane
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GET UNDER CONTROL!!!!

• Nucleus-contains cells DNA, manages cell
  function
• Surrounded by nuclear envelope
• Double membrane-pores allow movement
• Chromatin-long strands of DNA
• Packed into chromosomes

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Nucleus
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• Nucleolus
• Region inside nucleus
• Produces particles for protein synthesis
• Particles are called ribosomes
• Cell assembles enzymes according to DNA
• Not bound by membrane

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Nucleolus
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Assembly, Transport, Storage

• Cytoplasm-outside nucleus, surrounds organelles
• Clear liquid
• Important chemical reactions (protein assembly)
  take place here
• Endoplasmic Reticulum (ER)-
• Network of interconnected compartments
• Surface folded into cell
• Tissues in a box!
• Site for lipid synthesis in cell

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Smooth or Rough?

• Smooth ER
• Lacks ribosomes on surface
• Rough ER
• Studded with ribosomes on surface
• ER acts as cells delivery system!

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Structures for Storage

• Golgi Apparatus
• Closely stacked, flattened membrane sacs
• Receives proteins and lipids
• Modifies them chemically, repackages
• Distributes them throughout membrane
• Vacuole-sac of fluid
• Temporary storage of food, enzymes etc.
• Animal cell-small and numerous
• Plant cell-single large vacuole for water

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• Golgi Apparatus
• Vacuole

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Reduce, Reuse, RECYCLE!

• Lysosomes
• Digest excess or worn out cell parts, food
  particles, and invading viruses/bacteria
• Membrane protects digestive enzymes from rest of
  cell

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Energy Transformers

• Mitochondria
• Break down food-convert to energy!
• Peanut-shaped
• Highly folded inner membrane for more energy
  storage
• Chloroplasts-plants only!
• Transform light energy into chemical energy
• Chlorophyll-traps energy from sun
• Green color!

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NRG!!
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Support and Locomotion

• Cytoplasm
• 1. Cytoskeleton-network of fibrous elements
• Act as scaffold for organelle support
• 2. Microtubules-thin, hollow cylinders
• Made of protein
• 3. Microfilaments-thin, solid fibers
• Both make up most of cytoskeleton

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LETS GET MOVING!

• Cilia
• Short, numerous hair-like projections
• On cells surface
• Movement like the wave!
• Flagella
• Longer projections
• Whip-like motion
• One or two per cell

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Flagella vs Cilia
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Cellular Organization

• 1. Single-celled organisms Unicellular
• 2. Many-celled organisms Multicellular
• 3. Cells functioning together for activity
  Tissues
• 4. Two or more tissues functioning together
  Organs
• 5. Organs working together to carry out major
  life functionsOrgan System