The Cell

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The Cell

• Chapter 4

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Cells

• Marks the boundary between the living and the
  dead
• Structural and functional unit of an organism
• Smallest structure capable of performing all of
  the functions necessary for life

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What is a cell?

• Why do we care?
• We have TRILLIONS of them!! (_at_65)
• Every organism is composed of
  one or more cells
• Basic unit of structure and
• function in organisms
• All come from pre-existing cells

Cell Theory
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All cells.

• Have an outer plasma membrane
• Contain DNA
• Enclosed within the cell somewhere
• Contain cytoplasm

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Plasma Membrane and Cytoplasm

• All cells surrounded by a plasma membrane
• Phospholipid bilayer
• material inside a cell is the cytoplasm
• Everything between the plasma membrane and the
  region of DNA
• Gives cells their shape
• Assist in movement of cell and organelles

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Microscopes

• Compound light microscope
• Multiple lenses increase magnifying power

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Two basic kinds of cells

• Prokaryotic
• Nothing separates the DNA from
  internal cell parts
• Eukaryotic
• Contain organelle sacs
• Nucleus contains the DNA

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Eukaryotic Cells
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Examples of Eukaryotic Cells

• Animal
• Plant
• Fungi
• Protozoa

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Cell Walls

• Plant cells
• Permeable
• Protective
• In addition to a plasma membrane

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Organelles

• Organelles act as their own separate organs
• They physically isolate chemical reactions inside
  cells
• Animals and plants will differ in their organelles

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Nucleus

• Encloses the DNA of a eukaryotic cell
• Contains chromosomes
• Functions
• Prevents DNA from getting entangled with
  structures in the cytoplasm
• Outer membranes act as a boundary

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Components of the nucleus

• Nuclear pores
• Nuclear envelope
• Nucleolus
• Nucleoplasm
• DNA
• Chromosomes
• Chromatin

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Nuclear envelope

• Double-membrane system composed of lipid bilayer
  (with pores)
• Bilayers surround the fluid part of nucleus
  (nucleoplasm)
• Continuous with the endoplasmic reticulum

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Nucleolus

• Dense mass located within the nucleus
• Produces ribosomes

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Ribosomes

• Site of protein synthesis
• Occurs in the cytoplasm
• Attached to the endoplasmic reticulum
• Differ between prokaryotes and eukaryotes
• Why is this important from a health aspect?

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Endomembrane System

• Helps modify proteins into final form
• Lipids are assembled
• Compartmentalizes the cell
• Main components
• 1. Nuclear envelope
• 2. Endoplasmic reticulum (ER)
• 3. Golgi body
• 4. Various vesicles (transport)

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1. Nuclear envelope

• Merges with the membrane of the ER
• Consists of membranous channels and saccules

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2. Endoplasmic Reticulum

• Channel that snakes through the cytoplasm
• Lipids assembled and polypeptide chains modified
  into final proteins
• Can be rough or smooth
• Dependant on the attachments of ribosomes
• Rough ER
• Processing and modification of proteins
• Smooth ER
• Synthesizes phospholipids

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3. Golgi Body (Apparatus)

• Series of flattened sacs
• Collects, sorts, packages, and distributes
  materials such as proteins and lipids
• Contain enzymes that put the finishing touches on
  proteins and lipids

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4. Vesicles

• Enzymes from golgi apparatus sort and package the
  molecules into vesicles
• Tiny sac that moves through cytoplasm
• Function in transport, storage, or digestion of
  substances
• Two main types
• Lysosomes
• Peroxisomes

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Lysosome

• A lysosome is a membrane-enclosed sac
• contains digestive enzymes to break down
• Macromolecules
• damaged organelles

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Put it all together
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Energy-Related Organelles

• organelles specialize in converting energy to a
  form that can be used by the cell
• Requires solar energy
• Dissipates as heat
• Chloroplasts
• Use solar energy to synthesize carbohydrates
• Carbohydrates then broken down in the..
• Mitochondria
• Produce ATP molecules

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Energy-Related Organelles

• Photosynthesis

• Cellular Respiration
• The chemical energy of carbohydrates is converted
  at ATP

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Cytoskeleton Cilia and Flagella - Movement

• Hairlike projections
• Help in the movement of cells
• Some examples.
• Why would we need them?

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Vacuoles

• Membranous sacs
• contractile vacuoles of protists
• central vacuoles of plants

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Prokaryotes

• Archae
• Bacteria

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Prokaryotic Cells

• Cell Wall
• Capsule
• Flagellum
• Plasma membrane
• Nucleoid
• Plasmids
• Ribosomes