Chapter 7: Cellular Structure and Function
Big Idea: Cells are the structural and functional units of all living organisms
Section 7.1 The invention of the microscope led to the discovery of cells
Vocabulary Words:
Cell – is the basic structural and functional unit of all living organisms
Cell theory – one of the fundamental ideas of modern biology and includes three principles:
1. All living organisms are made up of one or more cells
2. Cells are the basic unit of structure and organization of all living organisms
3. Cells only come from other cells, with the “older” cells passing on copies of their
genetic material to the new cells
Plasma membrane – a permeable boundary that controls what enters and leaves the cells
Organelles – specialized structures in cells that carry out specific functions. Think of organs in our
bodies as a comparison, but only tinier.
Eukaryotic cells – unicellular organism with a membrane-bound nucleus and organelles; generally
larger and more complex than a prokaryotic cell. Uni = one so this is a one-celled
organism
Nucleus – different than what it means in chemistry. In biology, it is the center of the cell where
the membrane-bound organelle manages cellular functions and contains the DNA.
Prokaryotic cells – it is a microscopic, unicellular organism without a nucleus or other membranebound organelles
Notes:
History of the Cell Theory
 Before 1665, people didn’t know about cells or anything that could not been seen with the
naked eye.
 In 1665, Robert Hooke made the first (simple) microscope and observed a sample of cork
wood. He got to see the dead cells of the oak bark.
 Hooke coined the word cellulae which is Latin for small rooms. The cells of the bark
looked like little rooms to him.
 In the late 1600’s, Anton van Leeuwenhoek read Hooke’s work and was inspired to make
his own microscope. He observed living organisms in pond water, milk, and other things.
 In 1838, Matthias Schleiden studied plant tissues under the microscope and concluded all
plants are made up of cells.
 In 1839, Theodor Schwann said the same thing about animals.
 In 1855, Rudolph Virchow put out the idea that all cells are produced from the division of
living cells.
 All this came to be known as Cell Theory
Microscope Technology
 The more powerful the microscope, the more one can see.
 There are two types of microscopes to learn about right now: Compound Light
Microscopes and Electron Microscopes.
 Compound Light Microscopes uses light to produce a magnified image. It can only do so
much.
 Electron Microscopes can do a lot more than the other kind. During World War II
(1940’s), scientists created this by using magnets to aim a beam of electrons at thin slices of
dead cells. There are four types of electron microscopes: TEM, SEM, STM, and AFM.
o SEM can produce a 3D image
o STM can produce a 3D image BUT can be used on LIVE specimens
Basic Cell Types
 Different cells perform different functions. Those that perform the same function usually
are together – liver cells are found in the liver while skin cells are found on the skin.
 Cells break down molecules to generate energy for metabolism.
 There are two broad categories for cells: prokaryotic and eukaryotic.
 Eukaryotic cells are more complex and have organelles
 Prokaryotic cells are more simple, primitive. Scientists think they are similar to the very
first organisms on Earth.
 Most bacteria are prokaryotic
7.2 The Plasma Membrane
Vocabulary Words:
Selective Permeability – this is a key property of the plasma membrane. It is choosy about what it
lets in and out of the cell
Phospholipid Bilayer – plasma membrane layers composed of phospholipid molecules that are
arranged with polar heads facing the outside and nonpolar heads facing the inside
Transport proteins - this is a protein that moves around (transports) substances or wastes through
the plasma membrane
Fluid Mosaic Model – this is a plasma membrane that has components constantly in motion,
sliding past one another within the lipid bilayer
Notes:
Function of the Plasma Membrane
 It’s thin, flexible, and controls what comes and goes from the cell
 The membrane protects the inside of the cell from the watery environment in which it lives
 The membrane generally allows in nutrients and out waste
Structure of the Plasma Membrane
 Most of the molecules in the membrane are lipids.
 Lipids are made up of glycerol and three fatty acids. A lipid is basically a fatty substance.
 A phospholipid has had a phosphate to replace one of the fatty acids, thus making a
phospholipid.
 Look at figure 7.6 to figure this out on page 188
 The phosphate group in each phospholipid makes the head polar; it is attracted to the
water because the water is also polar. The two fatty acids are not polar and are therefore
repelled by the water – think about water and grease not mixing.
 The polar and nonpolar heads work together to create the plasma membrane and stabilize
the cell it in a watery environment.
7.3 Structures and Organelles
Vocabulary Words:
Cytoplasm - semifluid materials inside the cell’s plasma membrane
Cytoskeleton
Ribosomes
Nucleolus
Endoplasmic reticulum
Golgi apparatus
Vacuole
Lysosomes
Centrioles
Mitochondria
Chloroplasts
Cell wall
Cilia
Flagella – projections that aid in the moving and feeding of cells. Think of little hairs that whip
around and move
Notes:
Cytoplasm and Cytoskeleton
 This is the environment inside the plasma membrane
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Cell Structures
 A eukaryotic cell has different organelles that take care of different functions.
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Comparing Cells
 Plant cells have chlorophyll, vacuoles, and cell walls. Animal cells don’t.
Organelles at Work
 Comparison of a cell to a factory. Each organelle or area has its own function, like an
assembly line.
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7.4 Cellular Transport
Vocabulary Words:
Diffusion
Dynamic Equilibrium
Facilitated diffusion
Osmosis
Isotonic solution
Hypotonic solution
Hypertonic solution
Active transport
Endocytosis
Exocytosis
Notes:
Diffusion
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Osmosis: Diffusion of Water
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Active Transport
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Transport of Large Particles
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