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What is a cell?
Recall your work yesterday. When classifying
cells, what are the two groups scientists
separate cells into?
Light Microscopes and Total Power Magnification
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We can use microscopes to observe cells in
greater detail
Light microscopes are what we will use in
class
More complicated microscopes, like scanning
and electron transmission microscopes, allow
us to see prokaryotic and eukaryotic cell
differences in greater detail

To find this, multiply the power of the
objective lens (4X, 10X, 40X), by the power of
the eyepiece (usually 10X)

Example: A student is viewing a slide using an
objective lens with a power of 4X. What is the
total power magnification?

4 x 10 = 40X
Structure and Function of Living Organisms

A cell is the basic structural, functional, and
biological unit of all living organisms
 “The building block of life”

You are made up of about 37 trillion cells!!!
What do we know about cells?
▪ In 1665, Robert Hooke used an early microscope
to look at a thin slice of cork, a plant material.
▪ Cork looked like thousands of tiny, empty
chambers.
▪ Hooke called these chambers “cells.”
▪ In 1838, Matthias Schleiden concluded that all
plants were made of cells.
▪ In 1839, Theodor Schwann stated that all animals
were made of cells.
▪ In 1855, Rudolph Virchow concluded that new
cells were created only from division of existing
cells.
▪ These discoveries led to the cell theory.
1.
2.
3.
All living things are composed of cells.
Cells are the basic units of structure and
function in living things.
New cells are produced from existing cells.
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Prokaryotic
 Simple Cells
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Eukaryotic
 Complex Cells
 Plant and Animal Cells

Prokaryotic cells are
less complex than
eukaryotic cells
 No membrane bound
organelles; smaller

Single-celled
organisms (ex.
Bacteria)
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
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Eukaryotic cells are complex cells made up of
membrane bound organelles
Each organelle within the cell carries out
different roles
Eukaryotic cells make up complex organisms
(mostly multicellular)…like insects, fish, and
mammals like you!
PROKARYOTIC
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No membrane bound
organelles (no
mitochondria, nucleus,
vacuole, or chloroplasts)
Ribosomes
DNA and RNA (not
enclosed)
Circular DNA called
plasmids
Smaller size
EUKARYOTIC
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Contains membrane bound
organelles
Ribosomes
DNA and RNA (enclosed by
membrane)
DNA double-helix strands
Larger size
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What is a cell? What does cell theory tell us about cells?
Fill in the chart comparing the two basic categories of cells.
PROKARYOTIC
EUKARYOTIC
Animal vs. Plant
Animal Cell
•Nucleus
•Plasma
Membrane
•Mitochondria
•Vacuoles
•Ribosome
•Cytoplasm
•Lysosome
Plant Cell
•Nucleus
•Plasma
Membrane
•Mitochondria
•Ribosome
•Cytoplasm
•Vacuole (large)
•Chloroplasts
•Cell Wall
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The “control center”
Holds the DNA
Dark spot inside
nucleus is called the
nucleolus (it helps
makes the ribosomes)
Nucleus
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The “powerhouse” of the
cell
It produces most of the
energy for the cell
Breaks down food to
make ATP
 ATP is major fuel for all cell
activities that require
energy

Folded inner membrane
increase the surface area
for energy production
during respiration
Mitochondria
The “gate” of the cell
Double membrane
structure controls what
comes in and out of
the cell
 “YOU SHALL NOT
PASS”
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Plasma
Membrane
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Protein producer
The ribosome makes
proteins for the cell
Ribosome
“Storage tanks” of the
cell
 It stores food, water,
and chemicals in the
cell
 Plant cell vacuole is
much larger; controls
Turgor Pressure-keeps
plant upright (no
water=wilting)
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Vacuole
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Jelly/gel
A liquid/gel like
substance that
surrounds the
organelles
Cytoplasm
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The “garbage cans”
Break down and digest
waste products using
enzymes
Lysosome
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“Supporter/protector”
The cell wall shapes
and protects the plant
cell
Cell Wall
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Food producers
They are green
Contain green
chlorophyll and trap
energy from the sun
for photosynthesis
Chloroplast
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All these organelles work together to keep
the cell running!!
What do you think would happen if…
 The Mitochondria or chloroplasts stopped
working?
 The Plasma Membrane didn’t do it’s job?
 The Nucleus stopped directing activities?
1.
How are prokaryotic and eukaryotic cells similar?
a)
b)
c)
d)
2.
Both contain a nucleus
Both contain ribosomes
Both contain membrane-bound organelles
Both contain cell walls
This diagram shows a plant cell. Which structure is
found in a plant cell but absent in an animal cell?
a)
b)
c)
d)
1
2
3
4
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Nucleus
 “Brain of the cell”-controls cell functions and
stores DNA
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Mitochondria
 “Powerhouse of the cell”-makes energy through
cellular respiration; folded inner membrane
provides lots of surface area for cell processes

Cell membrane
 “Gate of the cell”-Double membrane structure
composed of lipids-controls what goes in and out
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Ribosomes
 Site of protein synthesis (makes proteins);
attached or free floating

Cytoplasm
 Gelly/jel that surrounds cells-keeps organelles
where they should be
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Vacuole
 “Storage center”-holds water, food, etc.-large in
plants due to Turgor Pressure
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Chloroplast
 Plants only-uses sunlight to convert to sugar
through process of photosynthesis
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Cell wall
 Plants only-carbohydrate called cellulose provides
rigid structure that protects and supports cell
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Lysosome
 “Garbage can”-animals only. Uses enzymes to
digest waste products
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Endoplasmic Reticulum-Network
of membranes that fold, modify,
and transports proteins
throughout the cell
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Golgi Apparatus-receives
proteins and lipids (fats);
modifies, sorts, and packs them;
works closely with the ER
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Cells all begin as
undifferentiatedDNA and genetics
play a role in
determining the type
of cell (ex. nerve cell,
muscle, blood…)
We will talk more
about this later!
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Mitochondria?
Chloroplasts?
Cell organelles can be more concentrated
based on needs!
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Candy Cells 
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Decide whether the cell is plant or animal. Next,
label the parts with the appropriate name.
Which cellular process is most closely related
the presence of chloroplasts in eukaryotes?
a) Metabolism
b) Photosynthesis
c) Aerobic respiration
d) Lactic acid fermentation
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Sepuplhs.org/high/sgi/teachers/cell_sim.html
Structure and Adaptations
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A “multicellular” organism is composed of
many cells (ex. You are composed of many
animal cells; plants are composed of many
plant cells)
“Unicellular” means they are composed of a
single cell!
 Ex. Bacteria, protozoa, euglena
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Unicellular organisms have many structures
that help them survive
 Contractile vacuoles
 Cilia
 Flagella
 Psuedopods
 Eyespots
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Stores excess water
that enters the cell, and
expels it to the exterior
 It expands when filling
with water, then
contracts, expelling the
contents back out
 Found in: protists +
unicellular algae
https://www.youtube.com/watch?v=pahUt0R
CKYc
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A dark area that functions in
light reception; influences
motion so that the
organism can move toward/
away from light
 Toward (positive phototaxis)
 Away (negative phototaxis)
 Found in: green algae;
photosynthetic unicellular
organisms
https://www.youtube.com/watch?v=QGAm6h
MysTA
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Cilia
 Many hair like structures
 Often used for movement
 Non-motile cilia serve as
sensory organelles
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Flagella
 Single, whip like tail used
for movement
 Found in: bacteria,
protists, specialized plant,
animal and fungi cells
https://www.youtube.com/watch?v=PsYpngB
G394
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Psuedopods
 “False feet” that help the unicellular organism
move about
 Sometimes used to obtain food (phagocytosis)

Recall that “taxis” is an innate behavior in
response to an outside stimuli
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Movement in response to chemicals (“chemo”).
Some single celled organisms direct their
movement according to chemicals in their
environment
Found in bacteria and singlecell or multicellular organisms
 Find food (e.g., glucose)
 Flee from poisons (e.g., phenol)
 Critical to early development
https://www.youtube.com/watch?v=2koAGkg
miqg
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Movement toward or away from light.
Many plant-like unicellular organisms will
move toward light to better photosynthesize,
just like plants will tilt toward the window
 Positive phototaxis: if the movement is in the
direction of increasing light intensity
 Negative phototaxis: if the movement is in the
opposite direction of light intensity