Chapter 7
Cell Structure and Function
Life is Cellular (7-1)
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The Cell Theory
 Robert Hooke- English physicist saw the
outline of cells in cork.
 Matthias Schleiden-said all plants are made
of cells.
 Theodor Schwann-said all animals were
made of cells.
 Rudolf Virchow- said that cells came from
pre-existing cells.
What is the Cell Theory?
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All living things are composed of cells.
Cells are the basic units of structure and
function in living things.
New Cells are produced from existing
cells.
Basic Cell Structure
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Cell Size
Average 5-50 micrometers in diameter
 Smallest 0.2 micrometers across (bacteria)
 Largest 1000 micrometers (Amoeba, Chaos
chaos) Seen without a microscope
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What are cells made of?
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Cell membrane- thin, flexible barrier
around the cell
Cell wall- Strong layer around the cell
membrane (plants only)
Nucleus-contains genetic material &
regulates cell functions
Cytoplasm-Material inside cell membrane
(not counting the nucleus)
Prokaryotes v. Eukaryotes
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Prokaryotes- smaller and simpler. Have
cell membrane, cytoplasm, but no nuclei.
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All bacteria
Eukaryotes-contains nuclei, cell
membrane, cytoplasm, and organelles.
Cell Structures (7-2)
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Cell wall- support (not in animal cells)
Nucleus- Contains DNA (hereditary info)
Discovered by Robert Hooke
Chromatin-DNA bound to proteins.
 Chromosomes- contains genetic info that is
passed to future generations
 Nucleolus- dense structure inside nucleus.
 Nuclear Envelope- Allows movement in & out
of the nucleus
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Cytoskeleton
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Helps cell maintain shape.
Involved in many forms of movement.
Microtubules-hollow tubes of protein that
help to make up cytoskeleton
Microfilament- Component of cytoskeleton
long thin fibers aide in movement &
support.
Organelles in the Cytoplasm
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Ribosomes- site of protein assembly
Endoplasmic Reticulum (ER)- where
components of cell membrane are
assembled.
Golgi Apparatus- enzymes here attach
carbohydrates & lipids to proteins.
Lysosome- Breaks down Carbs, lipids, &
proteins into forms usable by the cell.
Organelles cont.
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Vacuoles- Storage place for water, salts,
proteins, and carbs.
Chloroplast- Found mostly in plants. Use
energy from the sun to make food during
a process known as photosynthesis
Mitochondria- (power-house) Where
energy is made and stored.
Movement through the membrane
(7-3)
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Core of the cell membrane is a doublelayered lipid bilayer.
Concentration- amount of mass of a
solute in a given volume of solution.
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12g of salt, 3L of water= 12g/3L,or 4g/L
Diffusion-movement of molecules from
high concentration to low concentrationdoes not require energy.
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Osmosis- Diffusion of water through a
selectively permeable membrane (only
allows certain substances to pass)
Osmotic Pressure (effects of osmosis)
Isotonic- equal amount of dissolved materials
as inside the cell
 Hypertonic- Higher concentration of dissolved
materials than inside the cell. (Wilt)
 Hypotonic- Lower concentration of dissolved
materials than inside the cell. (burst)
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Facilitated Diffusion-movement of
substance through protein channels
instead of the cell membrane.
(does not require addition of energy)
Active Transport-Requires energy.
Endocytosis-takes materials into the cell
through “pocket” in the cell membrane
 Phagocytosis- when large particles are taken
into the cell by endocytosis. (Pac-Man)
 Exocytosis- removal of large amounts of
materials from the cell.
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Diversity of cellular life (7-4)
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Unicellular- 1 celled prokaryote/eukaryote
Multicellular- cell specialization (separate
roles for each type of cell)
Levels of organization
CellsTissuesOrgansOrgan system 
Organism
 11 major organ system (muscular, skeletal,
circulatory, nervous, etc.)
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