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Introduction to
Cells
MILLER AND LEVINE BIOLOGY 7.1 – 7.2
How do we know cells exist?
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In 1665 Robert Hooke used an early microscope
to examine a piece of cork (plant material).
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At the same time, Anton van Leeuwenhoek
used a single lens microscope to examine pond
water.
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Where did the term cells come from?
Cell Theory
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Following the discovery of cells, scientists agreed
that both plants and animals are made of cells
and are the smallest units of life. This lead to a
cornerstone of biology known as “Cell Theory”.
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Cell Theory states:
 All living things are made up of cells.
 Cells are the basic unit of structure and
function of living things.
 New cells are produced from existing cells.
How do we study cells?
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Light microscopes
How do we study cells?
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Electron microscopes
Two major cell categories
 Prokaryotic
 Bacteria
 Eukaryotic
 Animal
 Plant
cells
cells
What are the differences?
Prokaryotes
Eukaryotes
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Generally smaller and simpler
- Generally larger and
more complex
-
DO NOT separate genetic material
nucleus
- DO separate their
genetic material
in the nucleus
Eukaryotic
Prokaryotic
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Exocrine secretory epithelial cells
Salivary gland mucous cell (polysaccharide-rich secretion)
Salivary gland number 1 (glycoprotein enzyme-rich secretion)
Von Ebner's gland cell in tongue (washes taste buds)
Mammary gland cell (milk secretion)
Lacrimal gland cell (tear secretion)
Ceruminous gland cell in ear (earwax secretion)
Eccrine sweat gland dark cell (glycoprotein secretion)
Eccrine sweat gland clear cell (small molecule secretion)
Apocrine sweat gland cell (odoriferous secretion, sex-hormone
sensitive)
Gland of Moll cell in eyelid (specialized sweat gland)
Sebaceous gland cell (lipid-rich sebum secretion)
Bowman's gland cell in nose (washes olfactory epithelium)
Brunner's gland cell in duodenum (enzymes and alkaline mucus)
Seminal vesicle cell (secretes seminal fluid components, including
fructose for swimming sperm)
Why are cells small?
How are cells organized?
Within the cell are various
organelles
which you will read about in
chapter 7.2
(Pg. 196)
Nucleus