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CELLS
Essential question: What is the cell
theory?
Units of Life Cells):
History:
Anton van
Leeuwenhoek:
a. First to observe
organisms.
b. Designed own
microscope.
Robert Hooke
•
•
Studied cork cells.
Coined the word
“cell”.
Cell Theory:
•
•
•
Cells are the basic unit of structure.
Cells are the basic unit of function.
All cells came from preexisting cells.
Exceptions to the Cell Theory
Since all cells came from cells, what
produced the first cell?
Viruses are not composed of cells and do
no carry on most cellular activities, except
for reproduction and synthesis.
Mitochondria and chloroplast contain their
own genetic material and can reproduce
independently.
Essential question: What
are the types of cells?
Types of Cells:
Prokaryotes-cells without a
nucleus. Ex. bacteria
Eukaryotes-cells with a nucleus.
Essential question: What is an
organelle?
Organelles ( parts ) of a Cell:
Organelle -part of a cell with a specific
function.
Essential Questions: What is the structure
of the cell membrane? What is the
functions of the nucleus, nucleolus, and
ribosomes?
Cell Wall and Cell Membrane
Cell Wall:
•
•
•
Found only in plant.
Provides support and
protection.
Made up of cellulose (CH0).
Cell Membrane:
•
Controls the passage of
materials in and out of the
cells, thus protects the cell.
•
Said to be selectively
permeable.
•
Composed of two layers of
phospholipids, cholesterol
and protein channels.
Phospholipid - lipids (fats) with
phosphate group.
Nucleus:
•
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Control center of the
cell.
Protected by two
membranes
(nuclear
membrane).
Contains genetic
information
(chromosomes)
Nucleolous and Ribosome
Nucleolus:
• Found in the nucleus.
• Makes ribosomes.
Ribosome:
• Site of protein synthesis.
• Found floating in the cytoplasm or
attached to the endoplasmic reticulum.
Essential Questions: What are the
functions of ER, Cytoplasm,
Cytoskeleton and Golgi bodies?
Endoplasmic Reticulum (ER)
•
Series of
interconnecting
membranes.
•
Involved in storage ,
synthesis, and transport
of substances (mainly
proteins).
Two types of ER:
•
Smooth-Has no
ribosomes attached.
•
Rough- Has ribosomes
attached.
Cytoplasm:


Fluid-like environment between the
nucleus and the cell membrane.
Where organelles are suspended and
where many biochemical processes
occur.
Cytoskeleton:
•Skeleton of the cell.
•Constantly changing.
Golgi Complex:
•
•
Series of small
membrane-bound
sacs.
Involved in making
secretions. Sorts
proteins into
packages to be sent
out. Ex. Post office
Essential Questions: What is the functions
of the following organelles: Vacuole,
Lysosome, chloroplast, Mitochindria.
 What is difference between cilia and
flagella?

Vacuole: Temporary storage
area for materials. Exs.
Food, waste products,
water and enzymes.
•
Lysosmes:
Contain digestive
enzymes.
•
Involved in digestion of
worn out organelles
and food particles.
Chloroplast:
Chloroplast:
• Found only in plant
cells.
• Contains a green
pigment called
chlorophyll that
traps light energy.
• Site of
photosynthesis.
Mitochondria:
• Double membrane
structure.
• Site of respiration,
thus provides
energy for the cell.
Cilia and Flagella
Some cell surfaces have
cilia and flagella, which
are structures that aid in
locomotion or feeding.
Cilia- short, numerous hair
like projections that move
in a wave like motion.
Flagella-Long projections
that move like a whip.
Essential Question: What are the
differences between plant and
animal cell?
Plant Cells Versus Animal Cells
Organelle Plant Cell
Animal Cell
chloroplas present
t
absent
vacuole
large
small
cell wall
present
absent
central
absent
present
shape
rectangular
round
.
Cell Measurement:

The very small size of most cells
requires the use of a small unit for
measurement.
This unit is known as the
micrometer
( u m ). Cells often have diameters of
only 10-50 u m.
1,000 u m = 1 mm
