Transcript Chapter 7.2 PowerPoint

Chapter 3
Section 2 Cell Features
Objectives
• List the three parts of the cell theory.
• Determine why cells must be relatively small.
• Compare the structure of prokaryotic cells with that
of eukaryotic cells.
• Describe the structure of cell membranes.
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New Vocabulary
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Cell theory
Cell membrane
Cytoplasm
Cytoskeleton
Ribosome
Prokaryote
Cell wall
Flagellum
Eukaryote
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Nucleus
Organelle
Cilium
Phospholipid
Lipid bilayer
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• After Robert Hooke named the “cell” in 1665, it took
150
many scientists who were working together ______
years to understand what a cell was
Schleiden
– Matthias _____________,
a German botanist,
viewed many plants under a microscope
• In 1838, he concluded that all plant parts are
made of _______________
cells
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Schwann
• One year later, in ________,
Theodore _________
1839
concluded that all __________
animal parts are made of
cells
– Hint…Schwann sounds like swan
Virchow determined that all cells
• In 1858, Robert __________
preexisting
come from _________________
cells that
reproduced
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Chapter 3
•
Section 2 Cell Features
The work of these three scientists are the basis for
cell theory
the ___________________,
which has three parts:
made
1. All living things are _________
of one or more cells.
structure
2. Cells are the basic units of _____________
and
function
_________________
in organisms.
preexisting
3. All cells arise from ________________
cells.
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Chapter 3
Section 2 Cell Features
Cell Size
• Cells cannot grow too large because small cells
efficiently
function more ________________
than large cells
volume
• This is due to the fact that ________________
surface area
increases more quickly than _________________
• The surface area of this
cube represents the cell
membrane Its
____________.
volume contains all of its
parts
cell __________
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• If each side of the cube is 1mm long, what is its
surface area?
1 mm
6 to
– Find the area of one side and multiply by ____
find the total area of all the sides
2
1 mm
• Area = 1 mm x 1mm = _________
2
6
• Surface area = ________
=
1 mm x _____
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2
6mm
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• Find the volume of this cube
1 mm
– Volume = length x width x height
3
1mm x 1mm
1mm = ______
1mm
• Volume = ____
____ x ____
– So this cell’s surface area to volume ratio is…
6:1
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• Find surface area and volume for a cube with sides
that are 2mm long
• S.A. =
2
24 mm
2 mm
• Volume = 8 mm3
• So the s.a. to volume ratio of this cube is…
24:8
=
3:1
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• Find surface area and volume for a cube with sides
that are 4 mm long
• S.A. =
2
96 mm
4 mm
3
• Volume = 64 mm
• So the s.a. to volume ratio of this cube is…
96:64
=
3:2
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• Ratios can also be written as fractions
1 mm
6:1
6/1 =
6
2 mm
3:1
3/1 =
3
4 mm
3:2
3/2 =
1.5
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low
• If a cell’s surface area–to-volume ratio is too _____,
substances cannot enter and leave the cell well
enough to meet the cell’s needs.
• So if the cell grows too big, it won’t be able to get
in
out fast enough to
enough food _____
or waste ______
survive
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• Think of yourself in a crowded park
– One park is small and one park is big, but they are
both uniformly crowded or have the same density
Will it take you longer
to travel to the center of
the small park or the big
park?
big park
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• The same applies for food particles in a cell, so large
starving
cells end up ______________
from lack of food or
poisoned
being ____________________
by waste
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Question 1
• Who studied plants…Schleiden or Schwann?
Schleiden
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Question 2
• What are the three parts of the cell theory?
All living things are made of one or more cells.
Cells are the basic unit of structure and function in
organisms.
Cells come from preexisting cell.
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Question 3
• Why must cells be relatively small?
Because volume increases faster than surface area,
and if it gets too big, it will starve or be poisoned
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