Students will be able to answer the questions; 1. What is the cell theory? 2. What are the types of microscopes? 3. What are the differences between prokaryotes and eukaryotes? 4. What is the cell specialization and organization? 5. How do substances pass through cells?

1. Ch. 7 Cell Structure and Function

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3. Robert Hooke named the cell [1665] based on
observations of the cell walls of cork tissue
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7.1 Life is Cellular

4. Anton van Leeuwenhoek documented unicellular organisms
based on observations of protozoa [1673] and bacteria [1683]
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5. Matthias Schleiden proposed that cells were the basic units of
plants based on observations of plant tissue [1838]
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6. Theodor Schwann proposed that cells were the basic units of
animals based on observations of animal tissues [1839]
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Rudolph Virchow stated that [all cells arise from pre-existing
cells] based on observations of dividing cells [1855]

8. Schleiden and Schwann are credited as the founders of The
Cell Theory [1839]
 All living things are made of cells.
 Cells exhibit the basic characteristics of life:
 Obtain energy—photosynthesis, chemosynthesis, or
digestion
 Use energy—respire
 Excrete Waste
 Sense
 Reproduce
 Move
 Grow and repair damage to self 8

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The Cell Theory was described by three
statements;
 All organisms are made of cells
 Cells are the smallest structural and
functional unit of an organism [that
carries out the life processes]
 All cells come from pre-existing cells

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Microscopes
• Magnification: refers to the
microscope’s power to increase an
object’s apparent size
• Resolution: refers to the microscope’s
power to show detail clearly

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Light Microscope

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Light Microscope
Elodea - Aquatic Plant
40X 400X

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Electron Microscopes
• Electron microscopes reveal details 1000 times
smaller than those visible in light microscopes.
• Electron microscopy can be used to visualize
only nonliving, preserved cells and tissues.

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Transmission Electron Microscope (TEM)
• Used to study cell structures
and large protein molecules.
• Specimens must be cut into
ultra-thin slices

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Scanning Electron Microscope (SEM)

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Scanning Electron Microscope (SEM)
Mosquito Head
200X 2000X
• Produce three-dimensional images of cells
• Specimens do not have to be cut into thin slices

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Scanning Electron Microscope (SEM)
Inside of
Stomach
Surface of
TongueNeuron

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Prokaryotes and Eukaryotes
– How are prokaryotic and eukaryotic cells
different?
– Prokaryotic cells do not separate their genetic
material within a nucleus.
– In eukaryotic cells, the nucleus separates the
genetic material from the rest of the cell.

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– Although typical cells range from 5 to 50 micrometers in
diameter, the smallest Mycoplasma bacteria are only
0.2 micrometers across, so small that they are difficult
to see under even the best light microscopes.
– In contrast, the giant amoeba Chaos chaos may be
1000 micrometers in diameter, large enough to be seen
with the unaided eye as a tiny speck in pond water.
– Despite their differences, all cells contain the molecule
that carries biological information—DNA.
– In addition, all cells are surrounded by a thin, flexible
barrier called a cell membrane.
Prokaryotes and Eukaryotes

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– Eukaryotes are cells that enclose their DNA in
nuclei.
– Prokaryotes are cells that do not enclose DNA
in nuclei.
Prokaryotes and Eukaryotes

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Comparison between Prokaryotes and Eukaryotes

24. 7.2 Cell Structure
Animal Cell
Structure: the nucleus is a
sphere that contains
another sphere called a
nucleolus
Function: -storage center
of cell’s DNA
-manages cell functions
1. Nucleus
Structure: phospholipid bilayer with proteins
that function as channels, markers, and
receptors
-also contains cholesterol which provides
rigidity
Function: selectively permeable boundary
between the cell and the external
environment
2. Cell Membrane
Structure: gelatin-like
fluid that lies inside the
cell membrane
Function: -contains salts,
minerals and organic
molecules
-surrounds the organelles
3. Cytoplasm
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25. Cell Structure
Animal Cell
Structure: a network of
thin, fibrous elements
made up of microtubules
(hollow tubes) and
microfilaments (threads
made out of actin)
Function: -acts as a
support system for
organelles
-maintains cell shape
6. Cytoskeleton
Structure: consist
of two subunits
made of protein
and RNA
Function: location
of protein
synthesis
5. Ribosomes
Rough Endoplasmic
Reticulum (rER):
prominent in cells that
make large amounts of
proteins to be
exported from the cell
or inserted into the cell
membrane Covered
with ribosomes
4. Rough Endoplasmic
Reticulum
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26. Cell Structure
Animal Cell
Structure: consist
of two subunits
made of protein
and RNA
Function: location
of protein
synthesis
8. Ribosomes
Smooth Endoplasmic
Reticulum (sER):
involved in the
synthesis of lipids and
breakdown of toxic
substances Not
covered with
ribosomes
7. Smooth
Endoplasmic Reticulum
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27. Cell Structure
Animal Cell
Structure: spherical
organelles that contain
hydrolytic enzymes
within single membranes
Function: breaks down
food particles, invading
objects, or worn out cell
parts
11. Lysosome
Structure: folded
membrane within an
outer membrane The
folds of the inner
membrane are called
cristae
Function: -converts
energy stored in food
into usable energy
for work cellular
respiration
9. Mitochondria
Structure: stacked flat sacs
Function: receives proteins from
the rER and distributes them to
other organelles or out of the cell
(receiving, processing, packaging,
and shipping)
10. Golgi Apparatus
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28. Cell Structure
Animal Cell
Structure: composed of nine
sets of triplet microtubules
arranged in a ring Exist in pairs.
Function: centrioles play a
major role in cell division
(mitosis)
12. Centrioles
Structure: a sac of fluid surrounded by
a membrane Very large in plants and
many small vacuoles in animals
Function: used for temporary storage
of wastes, nutrients, and water
13. Vacuoles
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29. Cell Structure
Plant Cell
1. Cell Wall
Structure: rigid wall made up
of cellulose, proteins, and
carbohydrates
Function: boundary around
the plant cell outside of the
cell membrane that provides
structure and support
2. Chloroplasts
Structure: stacked sacs
(thylakoids) that
contain chlorophyll
surrounded by a
double membrane
Function:
photosynthesis
(conversion of light
energy to chemical
energy stored in the
bonds of glucose)29

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Comparison between Animal cell and Plant cell

31. 7.3 Cellular Transport
1. Passive Transport =
movement of substances across
the cell membrane without any
input of energy by the cell
A) Diffusion = movement
of molecules from high to
low (concentration)
- driven by the
concentration gradient
- spreads out evenly till
dynamic equilibrium is
reached
B) Osmosis = diffusion of water
A solution may be one of the
following: (compared to a cell) -
isotonic solution: same of water
and solute - hypotonic solution:
lower of solute, a lot of water -
hypertonic solution: higher of
solute, less water Hypertonic
Solution
Hypotonic
Solution
Isotonic
Solution
C) Facilitated
Diffusion
= move molecules
across the cell
membrane through
carrier/transport
proteins - are specific
for the type of
molecule they help
diffuse
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32. Active Transport =
substances can cross the
cell membrane with an
input of energy from the
cell
Cellular Transport
1) Endocytosis
= the process by which cells
ingest “stuff” - vesicle holds
the “stuff” - two types:
1) pinocytosis - solutes and
fluids
2) phagocytosis - large
particles or whole cells
2) Exocytosis
= the process by which
cells release “stuff”
- is essentially the reverse
of endocytosis
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7.4 Homeostasis and Cells
The Cell as an Organism
– How do individual cells maintain homeostasis?
– To maintain homeostasis, unicellular
organisms grow, respond to the environment,
transform energy, and reproduce.
– A single-celled, or unicellular, organism does
everything you would expect a living thing to do.
– Just like other living things, unicellular organisms must
achieve homeostasis, relatively constant internal
physical and chemical conditions.
– To maintain homeostasis, unicellular organisms grow,
respond to the environment, transform energy, and
reproduce.

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Homeostasis and Cells
Multicellular Life
– How do the cells of multicellular organisms work
together to maintain homeostasis?
– The cells of multicellular organisms become
specialized for particular tasks and communicate with
one another to maintain homeostasis.
– How do the cells of multicellular organisms work
together to maintain homeostasis?
– The cells of multicellular organisms become
specialized for particular tasks and communicate with
one another to maintain homeostasis.

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Homeostasis and Cells
Cell Specialization
– The cells of multicellular organisms are specialized,
with different cell types playing different roles.
– Some cells are specialized to move, others to react
to the environment, and still others to produce
substances that the organism needs.
– No matter what the role, each specialized cell
contributes to the overall homeostasis of the
organism.

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# Specialized Animal Cells
– Particles of dust, smoke, and bacteria are part of
even the cleanest air.
– Specialized animal cells act like street sweepers to
keep the particles out of the lungs.
– These cells are full of mitochondria, which provide a
steady supply of the ATP that powers the cilia on
their upper surfaces.
# Specialized Plant Cells
– Pollen grains are highly specialized cells that are
tiny and light, with thick cell walls to protect the
cell’s contents.
– Pine pollen grains have two tiny wings that enable
the slightest breeze to carry them great distances.

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Levels of Organization
– The specialized cells of multicellular organisms are
organized into tissues, then into organs, and finally into
organ systems.
– A tissue is a group of similar cells that performs a particular
function.
– To perform complicated tasks, many groups of tissues work
together as an organ.
– Each type of tissue performs an essential task to help the
organ function.
– In most cases, an organ completes a series of specialized
tasks.

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– A group of organs that work together to perform a specific
function is called an organ system.
– For example, the stomach, pancreas, and intestines work
together as the digestive system.
Levels of Organization
– The organization of the body’s cells into tissues, organs, and
organ systems creates a division of labor among those cells
that allows the organism to maintain homeostasis.

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Cellular Communication
– Other junctions allow small molecules carrying chemical
messages to pass directly from one cell to the next.
– To respond to one of these chemical signals, a cell must
have a receptor to which the signaling molecule can bind.
Sometimes these receptors are on the cell membrane,
although the receptors for certain types of signals are inside
the cytoplasm.
– The chemical signals sent by various types of cells can
cause important changes in cellular activity. For example,
such junctions enable the cells of the heart muscle to
contract in a coordinated fashion.
Video

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