Cells: The Basic Units of life
Introduction
What If…?
Imagine this scene from a
horror film. A young man sits
down to dinner to find that
his mother has made
asparagus again. The young
man eats the asparagus
stalks. Later he finds out that
instead of being digested, one
of the stalks has taken up
residence inside his body and
is very much alive! Too
horrifying to think about?
What if the asparagus began to do
wonderful things for the young man,
such as giving him more energy than
he ever dreamed possible? Lynn
Margulis, a scientist thinks that
something similar may have
happened to certain one celled
organisms that lived more than a
billion years ago, giving rise to the
kinds of cells that we are made of
today.
According to Margulis’s theory, about 1.2
billion years ago, some larger cells began
eating smaller cells for dinner. Like the
white blood cells in your body, these larger
cells trapped the smaller cells with
extensions of their cell body. But some of
these smaller cells resisted being digested.
In fact, they began to do very well in their
new homes. The larger cells also
benefited from their new guests. The
smaller cells released large amounts of
energy from food taken in by the larger
cells.
Other kinds of small cells used the
energy in sunlight to make enough
food to feed themselves and the
larger cell. The energy producing
structures of most cells, including
yours, are thought to have
descended from these smaller cells.
The energy producing structures
referred to are mitochondria and in
plants chlorophyll. One reason
scientists believe that mitochondria
were once separate organisms is that
they are not coded for in our genes.
Though they live within our cells,
they have their own genetic material
and independently make 90% of the
proteins they need to function.
If mitochondria are not coded for in
our DNA, how do we get them. They
exist in the cytoplasm of egg cells
and so are passed to us by our
mothers. They multiply
independently within our cells, so
that as our cells divide, mitochondria
are available in the cytoplasm of the
new cells. With the exception of red
blood cells, mitochondria exist in
every cell in our body.
Related questions:
• Where is it proposed that mitochondria came
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from.
Give 2 reasons which support this theory.
Which sex would be easier to clone. Why?
What is the only cell in our body that does not
have mitochondria? How might this effect these
cells?
The process of one organism living off another in
a way that benefits both is called symbiosis.
Name some other examples of symbiosis.
In what tissues might you find the most
mitochondria? The least?
Homework assignments
Hmwk. Quiz - on Friday 12/8
Essay - due on Monday. 12/11
Write a 1 pg. Single spaced science fiction story about an animal
whose cells are invaded by chloroplasts (the organelles in plants
that contain chlorophyll. Describe how the animals life processes
would be affected and how that animal would use this unusual
occurrence to its advantage. Choose to write about a mammal,
fish, bivalve, bird, reptile, insect, etc.
Attached to the essay should be a 3 sentence or longer quote from
any reference on what chlorophyll is and does. Be sure to write
who the author is and where you got the information. Do this first.
The Organization of Life
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C______
T______
O______
O____________
_
• O____________
_
organ
tissues
cells
Organ System
Organism
Cells
Cells are the _______________________.
A single cell has __________________________
________________________________________
Some organisms are made up of only one cell
Humans have approximately 100 trillion cells.
Though each starts as 1 and after many
divisions reaches 100 trillion
100,000,000,000,000
Humans have about 200 different
types of cells
Tongue skeletal muscle
& excretory glands
Thyroid cells
Name Some More!
Skin Epithelial Cells
Tissues
• A tissue is ___________________________
______________________________________.
• Some examples are – red blood cells, fat,
and muscle
Organs
1)
______________________
______________________
______________________
2)
Examples in animals?
3)
Examples in plants?
4)
What is the largest organ in
the human body?
5)
What are three organs that
help clean the blood?
6)
Which organ keeps us from
swelling up like a sponge
when we jump in the
swimming pool?
What are some plant organs?
Stamen, pistol, leaves, needles, etc.
Organ Systems
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_________________
_________________
_________________
Name some that
humans have. What
do they do?
Name some that
other animals
have like bats and
dolphins
Cells &
Organism
Name the Systems
What do they do?
Organisms
–
Organisms- _________________________
–
Unicellular – _____________. ie. –amoeba
or paramecium
–
Multicellular – _______________________
_____________________________ as part
of the group and would usually die if
removed from the group
Organism Interactions
Population – a group of organisms that are _________
____________________________________________
Communities – ________________________________
____________________________________________
Ecosystems- _________________________________
________________, such as water, light, soil and rocks
-terrestrial – on land – forests, deserts,
prairies, your backyard
-aquatic – rivers, ponds, lakes, oceans and
even an aquarium
The Organization of Life
Cells
Anton van Leewenhoek
Maybe Dutch’s grinder of lenses and
producer of glasses Zacharias Jansen
was the first to construct a microscope
about 1590. He used convex lenses.
Italian astronomer Anthony van
Leewenhoek, also a Dutch merchant
with clothes from Delf, contributed
sinificantly to improving the primitive
equipment. His hobby was blowing
glass and fine work with metal. He
grinded lenses accurately and
constructed them to produce strong
enlargement effects. Thanks to his
microscope he could watch a structure
of fibers from the clothes which he was
selling. Later he started to watch
leaves, flowers and small organisms
like bees or lice. He also studied human Van Leeuwenhoek (1632-1723)
blood, skin and hair. He was the first in
the world to see and describe blood’s
cells.
•The Leewenhoek
microscope was
simplicity in itself. It had a
single lens mounted on a
metal plate with screws to
move the specimen
across the field of view
and to focus its image.
The lens was the key and
permitted magnification of
70 to 270.
• In 1665 English physician and chemist
Robert Hooke invented the so called
compound microscope with more lenses.
He watched thin small plates of cork,
which was an often used material in the
shipping industry. He was the first to
accurately describe cells as living parts of
living things.
Given the following how do you
think the people below reacted to
this discovery?
Before the seventeenth century, no one knew that Cells existed.
Most Cells are too small to be seen with the unaided eye.
Cells were not discovered until after the invention of the microscope in the early
seventeenth century.
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Laypeople
Religious leaders
Kings
Other scientists
• Shortly after publication of Dialogue Concerning the Two
Chief Systems of the World - Ptolemaic and Copernican
the Inquisition banned its sale and ordered Galileo to
appear in Rome before them. Illness prevented him from
travelling to Rome until 1633. Galileo's accusation at the
trial which followed was that he had breached the
conditions laid down by the Inquisition in 1616. However
a different version of this decision was produced at the
trial rather than the one Galileo had been given at the
time. The truth of the Copernican theory was not an
issue therefore; it was taken as a fact at the trial that this
theory was false. This was logical, of course, since the
judgement of 1616 had declared it totally false.
• Found guilty, Galileo was condemned to lifelong
imprisonment, but the sentence was carried out
somewhat sympathetically and it amounted to house
arrest rather than a prison sentence
• It was a sad end for so great a man to die condemned of
heresy. His will indicated that he wished to be buried
beside his father in the family tomb in the Basilica of
Santa Croce but his relatives feared, quite rightly, that
this would provoke opposition from the Church. His body
was concealed and only placed in a fine tomb in the
church in 1737 by the civil authorities against the wishes
of many in the Church. On 31 October 1992, 350 years
after Galileo's death, Pope John Paul II gave an address
on behalf of the Catholic Church in which he admitted
that errors had been made by the theological advisors in
the case of Galileo. He declared the Galileo case closed,
but he did not admit that the Church was wrong to
convict Galileo on a charge of heresy because of his
belief that the Earth rotates round the sun.
How do lenses work?
• Refraction – _________________ when it
passes through different mediums.
• Think of a fish bowl or a glass of water
Preparing a slide (Wet mount)
Use lens paper to clean a glass slide and a coverslip.
Place your specimen on the center of the slide.
Place one drop of water onto the speimen (use medicine
dropper).
Hold the coverslip at the edge of the water at a 45 degree
angle to the slide.
Lower the coverslip slowly to avoid trapping air bubbles.
If specimen starts to dry add another drop of water at the
edge of the cover slip and blot dry with a paper towel.
Do the same if you wish to add stain
Utilizing the Microscope
1)
2)
3)
4)
5)
Always begin with the low power objective in line with the body tube
Place slide on the stage
Modify amount of light with diaphragm
Lower the objective lens down close to the slide (Never let it touch)
Turn the coarse adjustment to raise the low power objective until
the image is in focus
6) Use the fine adjustment to sharpen the focus
7) Position image directly in the center of the field
8) Switch to the next highest objective lens
9) If you goto the highest objective lens do not use the coarse
adjustment EVER.
10) When done remove the slide first
• http://micro.magnet.fsu.edu/primer/java/sci
enceopticsu/powersof10/index.html
Onion Slides
Muscle Cells
Pond Water Slides
• Eubacterium
• Amoeba
• Rotifer
• Hydra
• Paramecium
• http://www.microscopyuk.org.uk/index.html?http://www.microscop
y-uk.org.uk/pond/
The Cell Theory
Written 200 years after Hooke’s and
Leewenhoek’s discoveries by Schwann,
Virchow, and Schleiden
1) All organisms are ___________________
___________________________________
2) The cell is the ______________________
___________________________________
3) All cells come from __________________
Cell Similarities
All Cells Have:
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Cell membrane – the cell membrane acts as a
barrier between the inside of the cell and the
cells environment. It also controls the passage
of materials into and out of the cell.
Hereditary material – every new cell receives a
copy of the old cells DNA
Cytoplasm – the fluid inside a cell and everything
in the fluid is collectively known as cytoplasm.
Organelles – functional structures inside the cell
note: Not all cells have the same organelles
Do you know any that vary from cell to cell?
ATTACK OF THE GIANT CELL
Indescribable... indestructible... Insatiable
It crawls.... It creeps.... It eats you alive!
Why aren’t there giant Amoebas
waiting outside of schools to
engulf unsuspecting children?
Help! I’m
being eaten by
a giant cell
The lysosomes
are digesting me.
Surface to Volume Ratio?
Cell Size is Limited
Cells cannot get much larger because the food and
waste demands of the cytoplasm rapidly outpaces the
ability of the cell membrane to transport these
products based upon the surface to volume ratio.
The benefit of multicellular organisms
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_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
_______________________________________________
Why Can’t Cells Get That Big?
(Surface area to Volume Ratios)
1) ________________
__________________
2) _________________
__________________
3) _________________
___________________
The Blob Theme Song
http://kingtet.com/theblob.htm
Starring Steve McQueen
2 types of cells
• Prokaryotic – ________________________
(AKA bacteria)
• Eukaryotic – __________________________
Prokaryotes
• DNA is one _________________________
• ___________________________ except
ribosomes which produce proteins
• These bacteria were likely the first type of cells on
Earth
Weird Science
In 1969, the Apollo 12 crew retrieved a space
probe from the moon that had been launched
nearly three years earlier.
In the probe’s
camera, NASA scientists found a stowaway.
The bacterium Streptococcus mitis had traveled
to the moon and back. Despite the rigors of
space travel, more than 2 ½ years of radiation
exposure and freezing temperatures, the
Streptococcus mitis was was successfully
reconstituted.
Eukaryotes
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Cells are ______________________________________
Consists of ____________________________________
______________________________________________
Has __________________________________________
Has __________________________________________
Has __________________________________________
Cell Organelles
* in the eukaryotic cell
Cell membrane
• All cells ______________________
• ____________________ – keeps cytoplasm in,
allows nutrients in and wastes out
• _____________________________
Cell Wall
• Found only in ______________________
___________________________________
• __________________________________
___________________________________
• Because of the combined strength of
billions of cell walls, _________________
hundreds of feet tall without collapsing.
Nucleus
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Only found in ________________
The cell’s ___________________
Also covered by _______________
Stores _______________ – instructions for
making proteins
• Nucleolus- found _______________. It stores
the material to make ______________
• note: red blood cells are the only human cells
without a nucleus or mitochondria. Thus they
cannot reproduce. Lifespan 120 days.
Ribosomes
• Hook together amino acids to
_____________
• The only organelles not covered by a
membrane
Endoplasmic Reticulum
• The cell’s _____________________
• Makes lipids
• Moves substances through its many
tubular connections
• 2 types
– Rough – covered by __________________
– Smooth
Mitochondria
• The cell’s _______________________
• Makes _____________ – the _______________ molecule
• 2 membranes
– Outer – goes around the outside
– Inner – many folds – where ATP is made
Require___________ to work – you breathe so that you’re mitochondria
can have oxygen.
How long can you hold your breathe before passing out. That’s how
important mitochondria are.
Chloroplasts
• Found only __________________
• Contains ____________which converts
__________________ into ______ in the
presence of ____________. The sugar is used
by the plant’s mitochondria to make ATP.
Where did mitochondria and
chloroplasts come from?
• Many scientists believe that they used to be
prokaryotic cells that were eaten by larger cells.
– Mitochondria and chloroplasts are about the
_________________________________
– Both are surrounded by ______________. (The
original and the new one that was formed during the
engulfing process)
– Both have the same kind of ______________
______________________________________
– mitochondria are _____________ in our DNA
According to Margulis’s theory, about 1.2
billion years ago, some larger cells began
eating smaller cells for dinner. Like the white
blood cells in your body, these larger cells
trapped the smaller cells with extensions of
their cell body. But some of these smaller
cells resisted being digested. In fact, they
began to do very well in their new homes.
The larger cells also benefited from their new
guests. The smaller cells released large
amounts of energy from food taken in by the
larger cells.
Golgi Complex
• The cell’s ______________________
• _________________ are delivered here from
the ER where they ______________ for
different purposes. As these items exit the
golgi complex, they are enclosed in a small
compartment pinched off of the golgi complex.
This compartment travels to other parts of the
cell or outside the cell for delivery of it’s
contents.
Vesicles
• Membrane covered compartments
containing ______________________
Vacuoles
• Found primarily _________________
• A large membrane covered chamber filled
_______________________
• They often occupy large portions of the
cell
• When the vacuoles empty, the plant wilts
Goodness Grapeness
• The vacuoles in
grapes hold so much
juice that they must
dry in the sun for
several weeks before
they become raisins;
losing ¾ of their
original weight in the
process.
Lysosomes
• _____________________________
• Found in animal cells they contain
digestive enzymes.
• Responsible for the elimination of a
tadpoles tail and the webbing in a fetus’
fingers.
• Their destructive power may also be part
of the reason we age.
Plant vs. Animal Cells
• Awesome site with lots of info on cells
• http://www.sirinet.net/~jgjohnso/cell.html