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Chapter 7: CELLS
Introduction:
1. Robert Hooke an English scientist in the early 1600’s observed cells for the
first time using a compound light microscope to study cork, dead cells of
oak bark.
Before the invention of the microscope, no one knew about cells or
about microscopic organisms like bacteria and viruses.
Cell Theory
1. All organisms are composed of one or
more cells.
2. The Cell is the basic functional unit of
life. A single cell exhibits all 5
characteristics of life.
3. All Cells come from preexisting cells.
Cells divide to form 2 identical cells.
4. Cells pass on genetic information to
their Daughter cells in the form of
DNA.
•Cells are the smallest living units.
•They are organized & specialized.
Stomach Cells
(Cells)

Stomach Tissue
Stomach
(Tissue)
 (Organ)
Digestive System
 (Organ System)
1. The Cells: Cells are made up of
specialized parts called Organelles.
Each organelle has a specific
function for cell survival.
2. All the Organelles are suspended in
a clear, gelatinous fluid called
Cytoplasm.
Major Organelles and Their
Functions
1. Nucleus: controls the functions of a cell through
DNARNA Protein Trait.
a. Chromatin: Loose DNA inside the nucleus
containing over 600,000 pages of information giving
all of the directions on the structure and function of an
organism.
b. Nucleolus: a dark spot in the nucleus responsible
for the making of Ribosomes.
c. Nuclear Envelope: A semi- permeable, double
Phospholipid membrane that separates the nucleus
from the cytoplasm.
Major Organelles and Their
Functions
2. Cell Membrane: Controls what goes
in an out of a cell (Homeostasis).
Major Organelles and Their
Functions
3. Mitochondria: Produces energy for
the cell through the process of Cell
Respiration.
(
Power Plant)
Major Organelles and Their
Functions
4. Lysosomes: Breaks down worn out
cell parts and large molecules that
enter the cell with digestive enzymes
(Garbage Truck)
Major Organelles and Their
Functions
5. Ribosomes: Build Proteins
(Factory)
Major Organelles and Their
Functions
6. Endoplasmic Reticulum (ER): a Transport
system between the Nucleus and the
Cytoplasm.
A. Rough ER: its walls are lined with
Ribosomes. This organelle is folded many
times to provide more surface area for
Ribosomes. Function: Transports Proteins,
and is a site for chemical reactions.
B. Smooth ER: No Ribosomes. Function: Site
for Chemical Reactions and builds Lipids
Major Organelles and Their
Functions
6. Endoplasmic Reticulum (ER): a transports
system between the Nucleus and the
Cytoplasm.
Transit
System
(
Major Organelles and Their
Functions
7. Golgi Apparatus (Golgi Body):
Packages Proteins for export outside
the cell.
Major Organelles and Their
Functions
8. Cytoskeleton: is a support structure in
the cytoplasm. It forms a framework for
the cell, like your skeleton forms a
framework for your body.
The Cytoskeleton is made of:
A. Microtubules: Thin, hollow cylinders
made of protein.
B. Microfilaments: Thin, solid protein
fibers.
Major Organelles and Their
Functions
9. Cilia and Flagella: are structures
that aid in the locomotion and feeding
of cells. They are located on the
outside of some cells.
They are composed of pairs of
microtubules, with a central pair
surrounded by 9 additional pairs.
All surrounded by the Plasma
membrane.
Major Organelles and Their
Functions
9. Cilia and Flagella:
Major Organelles and Their
Functions
A. Cilia: Short, numerous, hair-like
projections that move in a wave like
motion
Major Organelles and Their
Functions
9. Cilia:
Major Organelles and Their
Functions
B. Flagella: are longer projections
that move with a whip-like motion.
Major Organelles and Their
Functions
9.Flagella:
Major Organelles and Their
Functions
9.Flagella:
Major Organelles and Their
Functions
Example of How Cell Organelles Work
Together
The Production and Exporting of Protien
1. Nucleolus- build ribosomes
2. Nucleus – sends instructions to the ribosomes
3. Ribosomes make protein
4. ER- Transports protein to Golgi
5. Golgi – Packages protein
6. Protein- Leaves the cell through the Cell
Membrane.
Cell Part
Function
City Counter
Part
I. EUKARYOTES Vs PROKARYOTES
2 types of cells
1.Prokaryotes: Don’t contain
membrane bound organelles or
nucleus. They are the most primitive
cells. Ex. Bacteria. All prokaryotes are
unicellular organisms.
2. Eukaryotes: Contain membrane
bound organelles and a Nucleus.
Organelles are separated into distinct
compartments.
Ex. Some unicellular organisms such
as algae and yeast. + all multicellular
organisms are Eukaryotes.
Characteristics Prokaryotes Eukaryotes
DNA
Loose in the Organized as
Cytoplasm, chromatin in a
organized in nucleus
a single ring.
Organelles
Contains
ribosomes
but no other
membrane
bound
organelle.
Life Forms
Unicellular Both unicellular
Ex. Bacteria AND
Multicellular
Contains
ribosomes and
many
organelles
Two Types of Eukaryotic cells:
Animals and Plant Cells: Both have all the
organelles we have talked about. There are
only a few differences. Plants have the
following:
1. Cell Wall: An inflexible barrier that protects
plants and some prokaryote cells and gives
it support. Plant cell wall is made up of the
Carbohydrate called Cellulose.
2. Vacuoles: Membrane bound sacs used for
storage of food, enzymes, water, and waste
products. Plant cells have much larger
vacuoles than animal cells.
3. Chloroplasts: organelles that capture light
energy food to store for a later time.
Photosynthesis
A. Chlorophyll: The pigment in chloroplasts
that traps light energy and gives leaves and
stems their green color.
4. Animal cells contain Centrioles, a structure
that plays a part in cell division.
Plants don’t have Centrioles.
Animal
Plant Cells
Cells
Contains a cell wall
No Cell wall
Chloroplasts
No
Chloroplasts
Large Vacuoles
Small
Vacuoles
Nucleus+ all the
Nucleus+ all
organelles we talked
the
about before except no organelles we
Centrioles
talked about
before +
Centrioles
CELL MEMBRANE AND CELLULAR
TRANSPORT
1. Plasma or Cell Membrane: maintains the
cell’s internal environment, maintaining
Homeostasis.
2. HOW? The plasma membrane is Selectively
Permeable: it allows some molecules into the cell
while keeping others out. Ex. A screen in a
window.
3. Structure: The plasma membrane is
composed of a Phospholipids Bilayer, 2 layers of
phospholipids back to back.
CELL MEMBRANE AND CELLULAR
TRANSPORT
Phospholipid: A lipid with a phosphate group
attached to it.
**Remember: Polar molecules attract polar
molecules. Polar attracts polar. Polar repels
non-polar.
*** Since Water is polar and is located both on
the inside and on the outside of cells:
The non-polar tails hide from the water but also
act as a barrier to it and to other polar molecules.
CELL MEMBRANE AND CELLULAR
TRANSPORT
Fluid Mosaic Model: The plasma
membrane is flexible. Phospholipid
molecules move within the membrane.
*Cholesterol: prevents the fatty acid
tails from sticking together. As a result,
it helps the membrane’s fluidity.
CELL MEMBRANE AND CELLULAR
TRANSPORT
**Transport Proteins: Proteins imbedded in the
membrane that span the membrane like floating
tunnels connecting the inside and the outside
environments of the cell. They open up at times
to allow needed molecules in and waste out.
CELL MEMBRANE AND CELLULAR
TRANSPORT
CELL MEMBRANE AND CELLULAR
TRANSPORT
***Marker Proteins: Proteins on the outer
surface of the Membrane. They help cells identify
each other like a uniform. It prevents your
immune system from attacking your cells. Ex.
Blood types and Bacteria.
CELL MEMBRANE AND CELLULAR
TRANSPORT
****Receptor Proteins: Proteins on the outer
surface of the cell membrane that act as a lock
for transport proteins. This helps our body control
what goes in and out of cells with the help of
hormones (endocrine system). Hormones act as
a key for the locks so cells will let certain
substances into cells when needed. Ex. Insulin /
Diabetes example.
Chapter 8.1 : Cellular Transport
In 1827, Scottish scientist, Robert Brown
observed what was later called Brownian
motion.
1. Brownian Motion: The random movement of
Particles.
All Molecules, solid, liquid, and gas have kinetic
energy, the energy of motion, and are
constantly moving.
The result of Brownian Motion is Diffusion.
Diffusion: the net movement of particles from an
area of higher concentration to an area of
lower concentration.
Ex. If you spray cologne into a room, the particles
of the fragrance will move from its
concentrated spray (Higher Concentration) to
the rest of the room (Lower Concentration) until
the particles are distributed evenly throughout
the room.
Diffusion is a slow process because it depends
on random movements of particles.
There are 3 factors that affect its speed:
A. Concentration: the more concentrated the
substance, the more rapidly diffusion occurs.
B. Temperature: increased temperature =
Molecular Movement = increased rate of
Diffusion
Pressure: increased Pressure = Molecular
Movement = increased rate of Diffusion.
Diffusion in Living Systems
Concentration Gradient: The difference in
concentration of a substance across space.
There are concentration gradients between the
water solutions outside cells and inside cells.
Outside Cell
Inside Cell
90%
50%
Water
Water
10%
50%
Other
Other
Substances will move with the concentration
gradient, from high concentration, to low
concentration until a Dynamic Equilibrium is
reached.
Dynamic Equilibrium: When materials moving
out of the cell = materials moving inside the
cell.
Human Example: Oxygen diffuses into the
capillaries of the lungs because there is a
greater concentration of Oxygen in the Air Sacs
of the lungs than in the Capillaries.
Osmosis: the diffusion of water across a
selectively permeable membrane. It is an
important of Homeostasis.
Isotonic Solution: There is an equal amount of
dissolved substances inside and outside the
cell. As a result, the concentration of water is
the same inside and outside the cell. – No net
movement of water = Dynamic Equilibrium.
B. Hypotonic Solution: The concentration of
water is greater outside the cell that inside. As
a result, water goes from the higher
concentration outside the cell to the lower
concentration inside the cell.
C. Hypertonic Solution: The concentration of
water is greater inside the cell than outside the
cell. As a result, water would go from the
higher concentration inside the cell to the
lower concentration outside the cell.
Real Life Example: Bacteria will not grow on fruit
preserves because when they land on the
sugar filled preserves, the bacteria shrivel up
loosing water weight until they die.
IV. TWO TYPES OF TRANSPORT
1. Passive Transport: Movement of particles
across a membrane down the concentration
gradient. Like going down stream in a canoe,
this requires no cell energy.
A. Ex. Diffusion and Osmosis
B. Facilitated Diffusion: Particles that can’t go
through the phospholipid bilayer or are too
large to pass through can still come through
the membrane with the help of transport
proteins.
* Transport proteins provide convenient openings
for particles to pass through, requiring no
energy.
2. Active Transport: Transport of particles into
and out of a cell from an area of low
concentration to an area of high concentration.
From low to high, up the concentration
gradient. Like going up stream in a boat, this
V. TRANSPORT OF LARGE PARTICLES:
1. Endocytosis: (in) is a process by which a
cell surrounds and takes in large materials
from its environment.
2. Exocytosis: (out) The reverse process
where large materials are exported from the
cell.