Cell Biology

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Cell Biology

• Cytology the study of cells
• Histology the study of tissues
• Levels of Organization cell---tissue---organ---s
  ystem
• Cell as basic unit of life
• Bathed in interstitial fluid (salt H2O)
• Structure related to function
• Variety of cell types (sizes, shapes, functions)
• Unicellular Organism consists of one cell
  (bacteria)
• Multicellular Organism consists of more than one
  cell

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• Prokaryotic Cell (Prokaryote) primitive
• Nuclear material spread out
• No nuclear membrane
• Examples Bacteria and blue-green algae
• Eukaryotic Cell (Eukaryote) advanced
• Nuclear material confined within a nuclear
  membrane
• Examples All cells except bacteria and
  blue-green algae
• Characteristics of Cells
• Nutrition involves the cells need for taking in
  food
• Digestion the breakdown of food
• Reproduction to make a copy
• Cellular Respiration food being changed into
  energy
• Excretion getting rid of wastes

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• Secretion to release a product
• Synthesis to make a product
• Irritability response
• Cell Theory
• Schleiden (1804-1881) Schwann (1810-1882)
• All living things are composed of cells.
• All cells are similar in structure and function.
• The structure and function of an organism
  involves the organization and action of all its
  cells.
• All cells come from pre-existing cells (Virchow)
• Exceptions
• Viruses
• Cell parts that reproduce (mitochondria,
  chloroplasts)
• Not all cells are separated by a cell membrane
  (muscle)

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Cell Biology Discoveries

• Robert Hooke (1665) coined the term cell
  (cork)
• DuJardin discovered cytoplasm
• Robert Brown discovered the nucleus
• Cell Organelles (Cell Parts)
• Protoplasm a clear jelly-like material (colloid)
• Contains H2O, wastes, nutrients
• Cytoplasm protoplasm within the cell membrane
• Keeps the cell hydrated

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Nucleus

• Control Center
• Controls everything in the cell
• Has a double-layered membrane with pores

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Chromosomes

• Control heredity
• Threads in the nucleus
• Contain DNA
• Human Body Cell (46)
• Human Sex Cell (23)

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Nucleolus

• Ribosome Factory
• 1-4 in the nucleus
• Make ribosomes

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Centrioles

• Involved in cellular reproduction
• Only in animal cells
• Rods outside the nucleus

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Mitochondria

• Powerhouse of the Cell
• Involved with energy/ metabolism/cellular
  respiration
• Contains cristae
• hold enzymes
• increase surface area

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Ribosomes

• Made by the nucleolus
• Involved in protein synthesis
• Attached on ER (protein sent out of the cell)
• Floating in the cell (protein within the cell)

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Endoplasmic Reticulum

• Channel inside the cell
• Rough ER contains ribosomes (protein sent out
  of the cell)
• Smooth ER does not contain ribosomes (fats
  sent out of the cell)

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Golgi Bodies

• Packaging Center
• Stack of coins
• Secretion

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Vacuoles

• Clear bubbles
• Hold Water
• Prevent dehydration
• Animal (small, several)
• Plant (few, large)

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Lysosomes

• Suicide Sacks
• Contain digestive enzymes
• Act as scavengers
• Eat old cell parts
• Related to aging, arthritis?

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Peroxisomes

• Detox Units
• Filters all poisons
• High number in kidneys and liver
• Tiny bubbles

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Microtubules/Microfilaments

• Skeleton of the Cell
• Microtubules (support or shape) mini tubes
• Microfilaments (cell movement) threads

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Plant Cell

• Cell Wall (to prevent dehydration)
• Chloroplasts (contain chlorophyll)
• Green organelles
• Involved in photosynthesis
• Large Vacuoles

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Cell Membrane

• Surrounds both animal and plant cell to prevent
  dehydration
• Semi-Permeable Membrane
• Contains pores
• Some particles move inside the cell Some
  particles move out of the cell Cell membrane is
  selective
• Movement depends on size of particles, chemistry
  of particles, temperature, pressure
• Sandwich Model (1935) Static model
• 2 phospholipid layers (phosphate fat) between 2
  layers of protein

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• Fluid Mosaic Model (1970) Dynamic model
• Proteins immersed in the 2 layers of
  phospholipids (fluid)

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Movement of Molecules

• Passive Transport
• No energy required
• Movement from a high concentration to a low
  concentration
• Diffusion
• A type of passive transport
• Movement of molecules from a high concentration
  to a low concentration
• Osmosis
• A type of passive transport
• Movement of H2O molecules from a high
  concentration to a low concentration through a
  membrane

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• Facilitated Transport
• Use of carrier proteins which carry molecules
  through the membrane
• Why does gargling with salt H2O help a sore
  throat?
• How does spraying vegetables keep them fresh?

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Types of Solutions

• Isotonic Solution
• Concentration of solute (dissolved materials) in
  the solution the concentration of dissolved
  materials inside the cell
• The concentration of H2O in the solution the
  concentration of H2O inside the cell
• Cells retain their normal shape

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• Hypertonic Solution
• Concentration of solute (dissolved materials)
  outside the cell is higher than the concentration
  of dissolved materials inside the cell
• There is more H2O inside the cell than outside
  the cell
• H2O will move out of the cell
• Pressure decreases and the cell shrivels
• Animal cell Cell shrivels up (Plasmolysis)
• Plant cell Cell membrane and cytoplasm pull away
  from the cell wall Plant wilts

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• Hypotonic Solution
• Concentration of solute (dissolved materials) is
  lower in the solution outside the cell than the
  concentration of dissolved materials inside the
  cell
• There is more H2O outside the cell than inside
  the cell
• H2O will move into the cell
• Pressure increases and the cell swells
• Animal Cell Cell could burst (Cytolysis)
• Plant Cells Cell wall prevents cytolysis high
  turgor pressure and plant cell becomes firm
  (stiff)

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• Active Transport
• Energy required
• Movement of molecules from a low
• concentration to a high concentration
• Bulk transport movement of
• large molecules across the
• membrane
• Endocytosis movement of large molecules into the
  cell
• Pinocytosis cell drinking taking in liquid
  and forming a vacuole
• Phagocytosis cell eating taking in a solid
  particle dissolved by digestive enzymes of a
  lysosome
• Exocytosis movement of large molecules out of
  the cell

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Preparation of a Wet Mount

• Place a drop of H2O on a clean slide
• Place the specimen in the drop of H2O
• Add stain (emphasizes cell parts)
• Place cover slip over specimen at a 450 angle
• Press out bubbles on the cover slip

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Lab Techniques

• Growing cells on glass (cell culture)
• Cell food (medium)
• Cell Fractionation separation of cell parts by
  high velocity (20,000X/min.) using a centrifuge
• Most dense cell parts settle to the bottom of the
  test tube
• Autoradiography injecting radioactive isotopes
  into cells/organisms as tracers