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THE CELL
• 1665- the first cells
were seen by Robert
Hooke
He saw empty cubicles
In cork from the bark of
a tree. He called them cells.
Cells he saw were dead with
only the cell wall left
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THE CELL
Scientists learned that the cell was filled with
fluid and that it contained a nucleus. (Brown)
1838- Schleiden- studied plant cells and he
concluded that all plants are made of cells.
1839- Schwann- said the same thing about
animal cells.
1858- Virchow- stated that all cells come from
pre-existing cells
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THE CELL THEORY
• All organisms are made of cells
• The cell is the basic structure and
function in organisms
• All cells are produced from preexisting cells.
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-nucleus
-cytoplasm
-nucleolus
-cytoskeleton
-cell membrane
-vacuole
-mitochondria
-chloroplast
-golgi Apparatus
-centrioles
-lysosomes
-ribosomes
-endoplasmic reticulum(ER) Rough ER & Smooth ER
- nuclear membrane
- cell wall
-chromosomes
- large central vacuole
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Nucleus
The “brain” of the cell
Controls all of the
cellular activities
DNA is inside the nucleus
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Nucleus
CHROMOSOMES- are found inside
the nucleus
carry the information that
Chromosomes – determines what traits a
living thing will have
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NUCLEAR
MEMBRANE
The “picky gate
keeper”- lets
some things in but
not others.
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NUCLEOLUS
The dark area in
the nucleus
 Makes
ribosomal
subunits.
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CELL MEMBRANE- PhosphoLipid Bilayer
 holds the cell together
 keeps all of the pieces (like the organelles
and the cytoplasm) inside the cell
 controls what goes in and out of the cellthe “gate keeper”
Example: like a tea bag with tiny holes
in it
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How does the cell membrane work?
Has 2 layers of MOLECULES = BILAYER
Bi means two
The layers are made up of molecules called
phospholipids
**THINK OF a sandwich with two pieces of
bread and some stuffing on the inside
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Cell Membrane: PHOSPHOLIPIDS
Each phospholipids
has a HYDROPHOBIC
and HYDROPHILIC
end
•HYDRO = means water
•PHOBIC = means afraid
•PHILIC = means loving
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Cell Membrane: PHOSPHOLIPIDS
 The fatty acid tails of the molecule are
“afraid” of the water and phosphate end
“loves” being in the water.
 Proteins are stuck inside the membrane
 Proteins are across the bilayer and make
the channels that let ions and molecules in
and out of the cell
Lipid bilayer with embedded
proteins!!!!!
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Cell Wall
 The cell wall is found in plant cells,
fungi, some protists and in
bacteria, but NOT in animal cells!
 The cell wall is made of different
things in different types of
organisms.
 Plant cell walls are made of
cellulose, a structural
polysaccharide.
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Cell wall
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Mitochondria
 Mito = Mighty / Power
 The Power-House of the cell
Aerobic cell respiration happens here
 They break down food molecules so the
cell has the energy (ATP)to live
 If a cell needs a lot of energy…it will have
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more mitochondria
The Mitochondria structure has three main
parts:
OUTER MEMBRANE:
covers the
mitochondria
INNER MEMBRANE:
folds many times to
increase the surface
area because
chemical reactions (glycolysis) occur here
So…the more space it has the more energy it
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can create
MATRIX: a fluid
that has water
and proteins all
mixed together
(like a solution)
•The proteins
take the food
molecules in and
combine them
with Oxygen to
release the
energy (ATP)
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Ribosomes
•small dot-like structures in cells
•they are often associated with forming
rough ER
•Ribosomes are the site of protein synthesis
in cells
•they are made by the nucleolus of the cell
•A ribosome can make the average protein in
about one minute
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Ribosome Structure
•Ribosomes are made up of proteins and
ribonucleic acid(RNA)
•These molecules are arranged into two
subunits
•These subunits are attached to each other
and together form the entire ribosome
•When viewed through a light microscope the
ribosomes appear as dots
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Types of Ribosomes
•There are two kinds of ribosomes
1) Attached to the rough ER-Attached
ribosomes make proteins that are part of
membranes or are secreted out of the cell
2) Floating in the cell cytoplasm-Free
ribosomes make proteins that are used in
the cytoplasm
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Endoplasmic Reticulum
 also known as the “ER”
 it is an organelle inside the cell that is
made up of membranes in the CYTOPLASM
of the cell, sort of like a vessel system.
There are two different
Smooth ER
Rough ER
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Smooth ER
 Main function is to transport things
 Breaks down poisons in our body
 Creates steroids- make sex hormones
 Stores Ions for the cell to keep nutrients
balanced
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Rough ER
It has bumps all over it giving it a “rough”
appearance
Bumps are called RIBOSOMES
ER collects the proteins (built by the
ribosomes) and creates a bubble around them
The proteins may remain embedded in the
ER membrane.
 VESICLE- is formed when the ER pinches
off a part of its membrane
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MOVEMENT of VESICLES
**The vesicle can then move to the Golgi
apparatus or the cell membrane
1)
If the vesicle has protein molecules
inside, like hormones or enzymes, then it will
float from the Golgi Body to the cell
membrane, the proteins are going to be sent
out of the cell… (exocytosis)
2) If the vesicle is empty but has embedded
proteins, it will become new cell membrane
when it attaches to the old cell membrane
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GOLGI APPARATUS
•Also called the Golgi Complex
• The packing and shipping yard of the cell
which is made up of a stack of flattened out
sacs …like a loose stack of pancake.
•Makes LYSOSOMES (animal)
•Makes vesicles for secretion out of the cell
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Think about building a model of a ship (that's the
molecule). Then take that model and put it in a
bottle (that's the vesicle).
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Golgi apparatus
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LYSOSOMES (animal)
•They combine with the food vacuoles formed
• by the cell
•The enzymes in the lysosome bond to food &
digest it (acidic interior)
• Next…smaller molecules are released which
are absorbed by the mitochondria and used to
make energy (ATP)
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LYSOSOMES
• When an organelle no longer works, the
lysosome will attach itself to it and break it
down like food (kind of like a cannibal)
– Chemicals can then be reabsorbed or
excreted
• Lysosomes can also destroy the cell if it
breaks open accidentally
– “Suicide Sacs”
– UV light damages lysosome membrane
• The enzymes inside the lysosome spread
throughout the cell and digest it
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LYSOSOMES
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Lysosome Animation
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CYTOPLASM
Cytoplasm- everything inside the cell membrane &
outside of the nucleus – Jelly-like, mostly water.
Keeps organelles in a homeostatic environment.
Anaerobic respiration occurs here.
cytoplasm
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CYTOSKELETON
• Chief functions include:
– movement of material through the cell
for stuff not diffusion or osmosis
– maintaining the shape of the cell
– keeping the cell from getting
smashed
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VACUOLE
• Vacuoles are “bubbles” that float in the
cell
• Vacuoles are more important to the
survival of plant cells than they are to
animal cells
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VACUOLE: STORAGE IN PLANT CELLS
• The large central Vacuole in plants support
structure. So, when there is no water…the
vacuole shrinks and the cell wall is the only
thing holding the plant together.
• Vacuoles hold onto things that the cell might
need…like a backpack
• There are some vacuoles that hold onto waste
products, similar to having a big septic tank
• Storing waste products protects the cell from
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contamination
You will know that a plant's vacuoles are
shrinking when you see the plant begin to
droop over
HOLDING UP THE WALLS
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Turgor Pressure- force exerted by the water
entering (osmosis) the vacuole, which then
swells exerting internal force on the cell wall
•Causes “rigidity” so the plant my increase
by stacking cells
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Chloroplast
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Chloroplast
•the site of photosynthesis in eukaryotic
cells
•disk-like structures
•composed of a single membrane
•surrounding a fluid containing stacks of
membranous disks
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•SOLAR energy
radiated from the
sun is captured by
plants(chloroplast)
Chloroplast
•Then it is
instantaneously
changed into
ELECTRICAL
energy
•Then packaged as
CHEMICAL energy
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Chloroplast
•photosynthesis takes place inside the chloroplast
the process in which plant use
Photosynthesis- water, carbon dioxide, and energy
form the sun to make food
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Centrioles:
•generally appear in animal cells
•they look like two cylinders at right angles to
one another
•they help to form the fibers that move
chromosomes around when the cell is dividing
•as animal cells prepare for cell division these
two centrioles separate and go to opposite
ends of the cell.
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Answer the following questions using your notes
1. Which organelle is known as the “Brain” of the cell?
2. If you look at a picture of a cell, how would you
recognize the nucleolus?
3. List the 3 main jobs of the cell membrane
4. Explain why the cell membrane has tiny holes made
of protein in it.
5. The term hydro means _________.
A. If something is hydrophobic it is _________
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B. If something is hydrophilic it is __________
6. Which organelle is known as the Power House” of
the cell?
7. Explain how you could distinguish the rough ER
from the smooth ER.
8. What is the main job of the smooth ER?
9. The process of H2O moving across the cell
membrane is called?
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10. What is the main function of a lysosome?
11. What happens if a lysosome breaks open?
12. Why are vacuoles important to PLANTS?
13. Which organelle is the site of photosynthesis?
14. What are the three main ingredients for
photosynthesis?
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15. Centrioles are usually found in __________ cells.
16. What is the main function of a centriole?
17. List the two places you can find a ribosome in an
animal cell.
18. What do ribosomes make?
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