3.1 The Cellular Level of Organization

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3.1 The Cellular Level of Organization

• All life is cellular
• Unicellular organisms like Archaea, Bacteria,
  protists
• Multicellular eukaryotes like fungi, plants, and
  animals
• Exceptions Viruses are acellular but exhibit
  life qualities when acting as a parasite within
  host cells

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3.1 The Cellular Level of Organization

• The cell is the structural and functional unit of
  an organism, the smallest structure capable of
  performing all the functions necessary for life.

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3.1 The Cellular Level of Organization

• Prokaryotic cells lack membrane enclosed
  structures. No nucleus or organelle
  compartments
• Eukaryotic cells possess membrane enclosed
  structures. Prominent nucleus and distinct
  compartments - organelles

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The Cell Theory

• All organisms are composed of one or more cells.
• Robert Hooke, Louis Pasteur, Leuwenhoek, Virchow
  and others helped form the cell theory

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The Cell Theory

• All organisms are composed of one or more cells.
• Cells are the basic living unit of structure and
  function in organisms.

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The Cell Theory

• All organisms are composed of one or more cells.
• Cells are the basic living unit of structure and
  function in organisms.
• All cells come only from other cells.

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Sizes of Living Things
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Surface Area / Volume Ratio

• The amount of surface area affects the ability to
  get materials in and out of a cell.
• Cells are small. Their size is limited. Size
  is limited by S/V ratio.

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Surface Area / Volume Ratio

• The amount of surface area affects the ability to
  get materials in and out of a cell.
• A cells increase in volume, the proportionate
  amount of surface area decreases.

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Surface Area / Volume Ratio
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Plasma Membrane and Cytoplasm

• All cells are surrounded by a plasma membrane
  (AKA cytoplasmic memb., cell memb.).
• The material inside of a cell is the cytoplasm.
• The plasma membrane regulates what enters and
  exits a cell.

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3.2 Prokaryotic Cells

• Smaller in size than Eukaryotes (1 10 microns)
• Unicellular, no nucleus or organelles
• Archaea
• Bacteria

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3.2 Prokaryotic Cells
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3.2 Prokaryotic Cells

• Cell Wall - Unique Polysaccharide, Peptidoglycan
• Capsule- Sugar coat
• Flagellum - Motor
• Nucleoid - DNA
• Ribosomes

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3.2 Prokaryotic Cells

• Cell Wall
• Capsule
• Flagellum
• Nucleoid
• Ribosomes

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Prokaryotes are

• Structurally simple
• Metabolically diverse
• Adapted to most types of environments

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3.2 Prokaryotic Cells
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3.3 Eukaryotic Cells

• Larger in size than Prokaryotes (10 to 50
  microns)
• Membrane bound organelles (compartments with
  specialized functions)

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3.3 Eukaryotic Cells

• Eukaryotic cells
• Are structurally complex
• Have a nucleus
• Possess membrane-bound organelles
• May have a cell wall

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3.3 Eukaryotic Cells
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3.3 Eukaryotic Cells Review these for
assessment test, particularly the animal cell
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The Nucleus

• Stores DNA

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The Nucleus

• Stores DNA
• Nucleolus - rRNA

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The Nucleus

• Stores DNA
• Nucleolus - rRNA
• Nuclear Envelope
• Nuclear pores

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Ribosomes

• Site of protein synthesis
• Two subunits (large and small)
• Subunits consist of rRNA and protein molecules
• Polyribosomes
• Several ribosomes with a single mRNA molecule

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Endoplasmic Reticulum

• Consists of membranous channels and saccules

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Endoplasmic Reticulum

• Rough ER
• Processing and modification of proteins
• Smooth ER
• Synthesizes phospholipids
• Various other functions

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Golgi Apparatus

• The Golgi apparatus collects, sorts, packages,
  and distributes materials such as proteins and
  lipids.

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Lysosomes

• Lysosomes contain digestive enzymes that break
  down unwanted, foreign substances or worn- out
  parts of cells

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Vacuoles

• Vacuoles are membranous sacs that store
  substances.
• For example
• Water
• Pigments
• Toxins

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Peroxisomes

• Membrane bound vesicles containing enzymes.
• The enzymes break down molecules and as a result
  produce hydrogen peroxide.
• Toxic oxygen waste products free radicals, can
  cause serious problems
• Detoxification by special enzymes like SOD to
  less toxic hydrogen peroxide
• Hydrogen peroxide is broken down to water and
  oxygen by the enzyme catalase

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Energy-Related Organelles

• Chloroplasts
• Mitochondria

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Energy-Related Organelles

• Photosynthesis Cellular Respiration

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Chloroplasts

• Site of photosynthesis
• Structure
• Double-membrane
• Stroma
• Grana
• Thylakoids
• Chloroplasts contain
• Their own DNA
• Ribosomes
• Enzymes

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Mitochondria

• Found in all eukaryotic cells
• Site or cellular respiration
• Structure
• Double-membrane
• Matrix
• Crista

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The Cytoskeleton

• Maintains cell shape
• Assists in movement of cell and organelles
• Assemble and disassemble as needed
• Three types of macromolecular fibers
• Actin Filaments
• Intermediate Filaments
• Microtubules

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Actin Filaments

• Anchored to the plasma membrane
• Allows intestinal microvilli to expand and
  contract
• Found in pseudopods allowing amoeboid movement
• Play a role in animal cell division

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Actin Filaments

• Actin interacts with motor molecules such as
  myosin.
• In the presence of ATP, myosin pulls actin along
• Example muscle cells

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Intermediate Filaments

• Intermediate in size between actin filaments and
  microtubules
• Functions
• Support nuclear envelope
• Cell-cell junctions, such as those holding skin
  cells tightly together

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Microtubules

• Hollow cylinders made of two globular proteins
• Assembly
• Under control of Microtubule Organizing Center
  (MTOC)
• Most important MTOC is centrosome
• Interacts with specific proteins to cause
  movement of organelles

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Microtubule Operation
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Centrioles

• Short cylinders with a 9 0 pattern of
  microtubule triplets

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Centrioles

• Help organize microtubules during animal cell
  division
• May be involved with microtubule formation and in
  the organization of cilia and flagella

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Cilia and Flagella

• Hairlike projections that aid in cell movement
• In eukaryotic cells, cilia are much shorter than
  flagella
• They are membrane-bound cylinders enclosing a
  matrix area
• The matrix consists of microtubules in a 9 2
  pattern

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Cilia and Flagella