Transcript The Discovery and Basic Cell Theory

Cell Structure and Function
Cell Structure and Function
 The discovery and the basic theory of cells.
 Cell size and number.
 The two major kinds of cells.
 Plant cells and animal cells.
 Cell me mbrane (plasma membrane).
 Cytoplasm.
 Nucleus.
 Ribosomes.
 Endoplasmic reticulum (rough ER and smooth ER).
 Golgi complex (body).
 Lysosomes.
 Peroxisomes.
 Mitochondria.
 Chloroplasts.
 Cytoskeleton.
 Vacuoles.
The Discovery and Basic Theory
of Cells
Robert Hooke
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About 1663, Hooke directed
an instrument maker to
improve his own microscope.
Robert Hooke Discovered and
Named Cells
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Hooke began to focus his
new instrument on everyday
objects.
When Hooke peered at a
thin slice of cork, he saw
what he called “pores” or
“cells”.
Anton Van Leeuwenhoek
Leeuwenhoek’s small, simple,
hand-held microscope
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Leeuwenhoek had far greater success at
seeing living cells such as Euglena.
He discovered bacteria and called them
“animalcules”.
Matthias Schleiden
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In 1838, Schleiden drew an important
conclusion based on years studying plant
tissues.
All plants, he said, are made up of cells.
Theodor Schwann
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In 1839, Schwann drew an important
conclusion based on years studying animal
tissues.
All animals, he said, are made up of cells.
Schleiden and Schwann
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1n 1839, both together published the even
broader conclusion that:
All living things are composed of cells.
Rudolph Virchow
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20 years later, Virchow stated that living
cells arise only from preexisting cells.
The Modern Cell Theory
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1. All living things are made up of one or
more cells.
2. Cells are the basic living units within
organism, and the chemical reactions of life
take place within cells.
3. All cells arise from preexisting cells.
Cell Size
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Not all cells have the same size.
We use the micrometer to measure the
sizes of cells.
There are 1,000 millimeters in 1 meter.
There are 1,000,000 micrometers in 1
meter.
Surface-to-Volume Ratio
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The life of a cell depends on exchanges of
materials with the environment.
Movement of of all these materials takes place
through the cell’s surface.
The larger a cell’s volume, the greater the amount
of material to be exchanged.
Since this exchange depends on the cell’s surface
area, the surface-to-volume ratio imposes limits on
cell size.
Surface-to-Volume Ratio
 Surface: 6x4= 24 cm2
Surface: 8x6= 48 cm2
Volume: 2x2x2= 8 cm3
Volume: 8x1= 8 cm3
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Surface-to-volume: 24/8= 3
Surface-to-volume: 48/8= 6
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Small size increases surface-to-volume ratio
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Question 1
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Four of the five answers listed below are
portions of a well-known theory. Select the
exception:
A. cells are the structural and functional
components of living things.
B. cells arise from preexisting cells.
C. all organisms are made up of cells.
D. all cells have a nucleus.
Question 2
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Select the correct statement:
A. as a cell increases in size, its surface-tovolume ratio increases.
B. as a cell decreases in size, its surface-tovolume ratio increases.
C. as a cell increases in size, its surface-tovolume ratio stays the same.
Question 3
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The fingerlike extensions of the outer
membrane of the cells lining the intestine
serve to:
A. increase the cells’ cytoplasm.
B. decrease the cells’ cytoplasm.
C. increase the cells’ surface-to-volume ratio.
D. decrease the cells’ surface-to-volume ratio.
Answers
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Question 1: D
Question 2: B
Question 3: C