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Cell Structure and Function. Cell Discovery and Theory. The Cell. A cell is the basic unit of structure and function Humans have trillions and trillions of cells You can’t see cells with the naked eye. Cell Dudes. Robert Hooke- 1665

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cell structure and function

Cell Structure and Function

Cell Discovery



the cell
The Cell
  • A cell is the basic unit of structure and function
    • Humans have trillions and trillions of cells
    • You can’t see cells with the naked eye
cell dudes
Cell Dudes
  • Robert Hooke- 1665
    • Looked at cork, saw little box-shaped structures and called it cellulae
  • Anton van Leeuwenhoek- late 1600s
    • Looked at pond water and milk and saw


cell dudes1
Cell Dudes
  • Matthias Schleiden- 1838-botanist
    • Studied plants and concluded that all plants are made of cells
  • Theodor Schwann- zoologist
    • Concluded that all animal tissues were made of cells
  • Rudolph Virchow- Suggested that cells come from cells
  • A compound light microscope has a 10X ocular lens and a 460X objective lens.
    • Where is the ocular lens? ____________________
    • Where is the objective lens? _________________
    • What is the total magnification ___________X
  • 2 Kingdoms
    • Eubackteria
    • Archeabacteria
  • No nucleus
  • DNA in a central nucleoid


  • Contains ribosomes
  • First organisms on earth
eukaryotic cells
Eukaryotic Cells
  • 4 Kingdoms
    • Protist (single celled)
    • Plants (cell wall/chloroplasts)
    • Animals (lack cell wall/lack chloroplasts)
    • Fungi (cell wall/lack chloroplasts)
  • Contain membrane bound organelles
    • Organelles are specialized structures that carry out functions
the cell membrane
The Cell Membrane
  • The cell membrane is selectively permeable
    • Some things can pass but others can’t
  • Cell membranes are made from a phospholipidbilayer
phospholipid bilayer structure


of cell







of cell




Lipid bilayer

PhospholipidBilayer Structure
  • Each phospholipid has a polar head and two nonpolar tails
    • Polar head is attracted to water
    • Nonpolar tails are repelled by water
phospholipid bilayer function
PhospholipidBilayer Function
  • The function is to let some things in and not others
    • Polar molecules do not easily pass
      • H2O is an exception because it is small
      • Allows membrane to separate environment inside from outside the cell
    • The plasma membrane is always in motion
      • Fluid mosaic model
animal cells plant cells
Animal Cells/Plant Cells
  • Eukaryotic cell which makes up tissues in animals
  • Lack cell walls and chloroplasts, and have smaller vacuoles.
  • Appears to be circular because of the lack of a rigid cell wall.
  • Eukaryotic cell that makes up plants
  • Cell Wall
  • Chloroplast
  • Large Vacuoles
  • Semi-fluid material inside the plasma membrane
  • Consists of cytosol and the cellular organelles (all organelles except the cell nucleus)
  • Cytosol - fluid in which the cellular organelles are suspended
  • Network of long, thin protein fibers provide an anchor for organelles
  • Microtubules-long hollow cylinders that assist in moving substances within the cell
  • Microfilaments-thin threads that give the cell shape and enable the cell to move

Cytoskeleton in

Red and Green

  • Contains genetic material (DNA)
  • Nuclear envelope
  • Nuclear pores allow substances in and out
  • Nucleolus in center
    • Very dense center
Produce proteins

Made of RNA and protein

Made in the nucleolus

Some float freely in the cytoplasm

Others attach to endoplasmic reticulum

endoplasmic reticulum
Endoplasmic Reticulum
  • Interconnected network of tubules
  • Rough ER
    • Where ribosomes attach and make proteins
    • Appear to create bumps and rough areas on the membrane
  • Smooth ER
    • No ribosomes
    • Produces complex carbohydrates and lipids
golgi apparatus
Golgi Apparatus
  • Modifies, sorts, and packs proteins in sacs called vesicles
  • Vesicles fuse with plasma membrane
  • They release proteins which move through membrane to get outside of the cell
  • Act as temporary storage unit for materials in the cytoplasm
  • Store, transport, or digest food and waste
  • Plant cells have one large one
  • Animal cells have little ones
  • Vesicles that contain digestive enzymes to digest excess or worn-out organelles and food particles
  • They also digest bacteria and viruses that enter the cell
  • They are built in the Golgi apparatus.
  • Microtubules
  • Found near nucleus
  • Animal Cells only
  • Aid in cell replication
  • Powerhouse
  • Converts organic materials into energy
    • ATP
  • Outer and inner membranes with lots of folds
    • Provides large surface area to break sugar molecule bonds (produce energy)
chloroplasts plant only
Chloroplasts- Plant only
  • Capture light energy and convert it to chemical energy through photosynthesis
cell wall
Cell Wall
  • Mesh of fibers that surrounds the plasma membrane
  • Protects and supports the cell
  • Made of carbohydrate, cellulose
cilia and flagella
Cilia and Flagella
  • Cilia- short projections that look like hairs
    • Move back and forth like oars on a rowboat
    • Move substances along surface of the cell
  • Flagella- longer projections that move in a whip-like motion
  • Both are composed of microtubules
  • Move cells through watery environment
cell transport
Cell Transport
  • Diffusion -net movement of particles from high concentration to low concentration
    • Doesn’t require energy because the particle are in motion
  • Dynamic equilibrium- the overall concentration does not change, but molecules are still moving randomly
what affects the rate of diffusion
What affects the rate of diffusion?
  • What makes molecules move faster
    • High temperature
    • High Pressure
    • High concentration
facilitated diffusion
Facilitated Diffusion
  • Some ions and molecules can’t diffuse across the cell membrane
  • Facilitated diffusion – uses transport proteins to help move some molecules across the plasma membrane
  • Osmosis – diffusion of water
  • Most cells undergo osmosis because they are surrounded by water
hyper hypo iso tonic
Hyper—Hypo– Iso tonic
  • These are comparing words
    • Hypertonic -more solute than
    • Hypotonic- less solute than
    • Isotonic- same solute as
  • What would happen if you
    • Put a red blood cell in a hypertonic solution
    • Put a red blood cell in a hypotonic solution
    • Put a red blood cell in an isotonic solution
active transport
Active Transport
  • Goes from low to high concentration
  • Requires Energy
    • ATP
  • Moves large substances
  • Endocytosis- moving large substances into the cell
  • Exocytosis- moving large substances out of the cell