Cells
The building blocks of life.
Composite Cell
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Cells in the body vary in size, shape, and
function
This chapter describes a “generic” cell’s
structures and their functions, as well as how
they grow and reproduce
Similar to Fig
3.2
© 1995-2005 by Michael W. Davidson and The Florida State University
Membrane Structure
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Composed mainly of lipids, proteins, and a
few carbohydrates
Bilayer of phospholipid molecules
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Lipid soluble molecules (oxygen, and CO2) pass
through easily
Impermeable to water soluble materials
(amino acids, proteins, sugars etc)
Membrane Structure
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Protein channels allow for transport of some
materials across membrane
Surrounds cytoplasm – clear, gelatinous fluid
inside a cell
Fig. 3.3
Assembly – Endoplasmic Reticulum

site of cellular chemical reactions
Series of highly folded membranes in the
cytoplasm
 Rough ER – ribosomes attached to ER perform
protein synthesis
 Smooth ER – biochemical activities

 Ex.
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production and storage of lipids, etc
Fig. 3.4
Similar to Fig
3.4
© 1995-2005 by Michael W. Davidson and The Florida State University
Transport – Golgi Apparatus
After proteins are made, they are transferred to
the:
 Golgi Apparatus – flattened stack of tubular
membranes that modifies the proteins
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Sorts proteins into “packages” and packs them into
membrane-bound structures (vesicles) to be sent to
the appropriate destination
Similar to Fig
3.5
© 1995-2005 by Michael W. Davidson and The Florida State University
Energy – Mitochondria

the "power plants" of the cell because they
make the cell’s energy
Use the energy from food to make high-energy
compounds that the cell can use to power growth,
development, and movement
 Energy is made by the mitochondria as it "digests"
sugar molecules.
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Mitochondria cont.

Has an outer membrane and
a highly folded inner
membrane
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Folds in inner membrane
provide greater surface area
Energy storing molecules are
produced on inner folds
Some cells have more
mitochondria than others
depending on the function
Bellwork

Write down the name of the nicest high
school student you know and describe why
you feel that way about them.
Recycling – Lysosomes

Small sacks inside the cell which contain
enzymes.
These enzymes "digest" old molecules of DNA,
protein, or lipids into small pieces
 Aid in disposal of intracellular bacteria and other
foreign bodies, as well as unwanted organelles
 May cause destruction of the cell if ruptured
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Centrosome
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Consists of two hollow cylinders called
centrioles

Centrioles function in cell reproduction by
distributing chromosomes to newly forming cells

Spindle fibers
Locomotion – Cilia & Flagella
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Cilia – short, numerous projections that look like
hairs that aid in locomotion or feeding
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Flagella – longer projections that aid in locomotion
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Motion similar to those on a rowboat
Made of microtubules
Move with a whip-like motion
Made of microtubules
Fig 3.9
Storage – Vesicles (Vacuoles)

Membrane-bound sacs

Act as storage depots for:
 Water
 Waste
products
 Soluble pigments
Support - Cytoskeleton

support structure within the cytoplasm

Forms framework of the cell
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Can be changed to change cell’s shape
Made of network of tiny rods and filaments
Microtubules – thin hollow cylinders made of
protein
Microfilaments – smaller, solid protein fibers
Cytoskeleton cont.
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Microtubules and
microfilaments form a
scaffold to maintain cell
shape
Also anchor and support
many organelles
Fig. 3.7
Cell Control – Nucleus
Highly specialized organelle that serves as the
information processing and administrative
center of the cell
 Contains directions to make proteins

Similar to
Fig. 3.10
© 1995-2005 by Michael W. Davidson and The Florida State University
Nucleus cont.
Chromatin – strands of DNA (genetic
material which contain directions for protein
making)
 Nucleolus – makes ribosomes
 Ribosomes – sites where the cell produces
proteins according to the directions of DNA
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