Cell Structure and Function I

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Cell Structure and Function I
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Cell Theory

• 1. All living things are made of cells.
• 3. New cells are produced from existing cells
• 2. Cells are the basic unit of structure and
  function in living things.

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Cell Exploration

• Light Microscopes
• Living organisms can be seen
• Light limits the resolution
  so extremely small things
  like proteins and viruses
  cannot be observed

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Cell Exploration

• High resolution video technology
• Allows scientists to see time elapsed movies of
  cells as the grow, divide and develop.
• http//www.cellsalive.com/mitosis.htm

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Cell Exploration

• Transmission
  Electron
  Microscopes
  (TEMs)
• Can see more detain and extremely small
  structures
• Beams of electrons must pass through ultra-thin
  sliced samples therefore no living things can be
  seen

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Cell Exploration

• Scanning Electron Microscope (SEMs)
• Beams of electrons scanned over the surface of a
  specimen
• Produces a 3D image
• Samples must be chemically
  preserved
  and removed of all
  water so no living
  things can be seen.

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Prokaryotes vs. Eukaryotes

• Prokaryotes
  (bacteria)
  have no nucleus
  and very few
  organelles. DNA is
  not contained
• Eukaryotes
  (protists, fungi, plants and animals) larger,more
  complex,DNA is inside the nucleus

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Plant Cells Vs. Animal Cells

• Both plant and animal cells contain a variety of
  organelles. Some structures are specific to
  either plant cells or animal cells only.
• Only plant cells contain
• Cell wall
• Chloroplasts
• Large central vacuoles
• Only animal cells contain
• Centrioles

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Smooth ER vs. Rough ER

• Rough ER - ribosomes on the ER make proteins, the
  ER modifies the proteins
• Smooth ER - makes lipids

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Mitochondria vs. Chloroplasts

• Mitochondria make energy from chemicals (food
  molecules)
• Chloroplasts make energy from light
  through photosynthesis

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Cytoskeleton

• Network of protein filaments
• Maintains shape
• Involved in cell movement

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Prokaryotes
Eukaryotes
Nucleus Endoplasmic reticulum Golgi
apparatus Lysosomes Vacuoles Mitochondria Cytoskel
eton
Has a Cell membrane DNA
DNA is free floating
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Cell Structure and Function II
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Cell Wall

• Provides support and
  protection for plant
  cell walls
• Made of porous cellulose
  so it does not regulate
  what enters and
  leaves

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Phospholipids are Building Blocks of Cellular
Membranes
The hydrophilic head group and hydrophobic tails
are the keys to phospholipid function.
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Phospholipids Form Biological Membranes
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Cell Membrane

• Regulates what enters and leaves the cell and
  provides support and protection
• Structure lipid bilayer with embedded proteins

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Diffusion through Cell Boundaries

• Particles move from an area of high concentration
  to an area of lower concentration
• No energy is required

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Osmosis

• Diffusion of water through a selectively
  permeable membrane

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Is this really Osmosis???
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Isotonic"ISO" means the same

• Concentration of solutes (salts) is the same
  inside and outside of cell.
• Water flows in and out in equal amounts
• No effect on cell

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HypertonicHyper means more

• Concentration of solutes is greater outside the
  cell than inside
• Water flows out of cell
• The cell shrivels and may die.
• This is why it is dangerous to drink sea water
• This is also why "salting fields" was a common
  tactic during war, it would kill the crops in the
  field, thus causing food shortages.

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Hypotonic "HYPO" means less

• Concentration of solutes is less outside the cell
  than in.
• Water flows in
• The cell swell with water and becomes turgid

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Active Transport

• Carried our by protein pumps found in the
  membrane
• Energy is required

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Facilitated Diffusion

• Molecules move through protein channels.
• No energy required

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Endocytosis

• Cell takes material into cell by infolding of the
  cell membrane
• Phagocytosis eating cell engulfs large
  particles
• Pinocytosis drinking cell takes in liquid
• www.endocyte.com/ animation/animation.htm

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Exocytosis

• Cell releases large
• amounts of material

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Cell Differentiation

• The cells in multicellular organisms can develop
  in different ways to perform different tasks.

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Levels of Biological Organization

• Organism
• Organ system
• Organ
• Tissue
• Cell
• Organelle
• DNA
• Atoms