This document discusses cells and their cellular nature. It begins by introducing the topic of cells and how they relate to the common characteristic of all living things being cellular. It then discusses the history of cell discovery, including the invention of the microscope and key figures like Hooke, Leeuwenhoek, and those who developed the cell theory. It also covers basic cell structures like organelles, differences between prokaryotic and eukaryotic cells, and examples of different cell types.

1. THE CELL
UNIT 4 will cover cells . These topics are all related to one of the
common characteristics of all living things.
ALL LIVING THINGS ARE COMPOSED
OF CELLS

2. What the heck is
a cell anyway?

3. It can also be considered as …

4. Finally it can be considered as…

5. Do you remember when we listed
that one of the common
characteristics of all living
organisms was that they had a
cellular nature?
This means they were either
composed of a singular cell
(unicellular) or made up of many
cells (multicellular)

6. Unicellular Organisms
(Living organisms made up from one cell.)

7. Multicellular organisms are
composed of many cells.
(for example our stomach contains many cells of many different types.)

8. SO…How is the study of cells related to our
Ecological (Rivers ) Biology? Your Ideas?

9. All cells are made from the big 4
macromolecules of life.
(Do you remember them?)

10. In some ways cells could be considered
little ecosystems in that…
• They require energy.
• They cycle materials.
• They are interactions
within different parts
of the cell.

11. In this unit we will explore the
cellular nature of life
by focusing on the similarities and differences
between cells of different life forms.

12. Science in its historical perspective
First…a little history….
A long time ago, people believed in something called Spontaneous
Generation- since at least the time of Aristotle (4th Century BC),
people believed non-living objects can give rise to living organisms.
It was common “knowledge” that simple organisms like worms,
beetles, frogs, and salamanders could come from dust, mud, etc., and
food left out.
BUT THEY WERE WRONG!

13. Because they were wrong,
we need a story to clarify
and explain the truth.
Once upon a time a long
time ago…
…the microscope was
invented.
(mikros = small; skopo = observe)

14. HANS AND SON
Sometime about the year 1590,
two Dutch spectacle makers,
Zaccharias Janssen and his
father Hans started
experimenting with these
lenses. They put several
lenses in a tube and made a
very important discovery. The
object near the end of the tube
appeared to be, much larger
than any simple magnifying
glass! They had just invented
the compound microscope.

15. Galileo
Galileo heard of their
experiments and started
experimenting on his
own. He described the
principles of lenses and
light rays and improved
both the microscope and
telescope. He added a
focusing device to his
microscope and went on
to explore the heavens
with his telescopes.

16. Anton von Leeuwenhoek of Holland became very
interested in lenses while working with magnifying
glasses in a dry goods store. He became so interested
that he learned how to make rounded lenses which
produced greater magnification, and his microscopes
were able to magnify up to 270X!
Leeuwenhoek became more involved in science and
with his new improved microscope was able to see
things that no man had ever seen before.
Anthony Leeuwenhoek (1632-1723) has since been
called the "Father of Microscopy".

18. Then in 1665 English Scientist Robert Hooke used this new
microscope!
Hooke discovered plant cells -- more precisely, what Hooke saw
were the cell walls in cork tissue. Hooke coined the term "cells":
the boxlike cells of cork reminded him of the prayer cells in a
monastery.
Robert Hooke's sketches of cork
cells.

19. Check out the dates. While the microscope was rocking back in
1665, it was not until the early 1800’s that the idea of cells was put
together with its relationship to living things!
In 1809 Jean Baptiste Pierre Antoine de Monet Chevalier de
Lamarck, remarked that “No living thing can have life if its
parts are not made of cellular tissue or are not formed by
cellular tissue.”
His theories were largely ignored or
attacked; He never won the acceptance
and esteem of his colleagues, and he
died in poverty and obscurity

20. • 1838 Schleiden- observed that all plants seemed to be composed
of cells
1839 Schwaan- extended Schleiden's cell theory to animals, stating
that all living things are composed of cells. Came up with the term
“CELL THEORY”
1858 Virchow- German pathologist Rudolf Virchow (1821 - 1902)
altered the thought of cellular biology with his statement that
"every cell comes from a cell“ a theory called BIOGENESIS
From their discoveries:
THE CELL THEORY AROSE…

21. • THE CELL IS THE BASIC UNIT OF
LIFE.
• ALL LIVING THINGS ARE
COMPOSED OF CELLS.
• ALL CELLS COME FROM OTHER
CELLS.

22. PERSON GETS
CREDITED
WITH:
Leeuwenhoek Microscope
Hooke Found plant/cork cells and
can up with term “cells”
Lamarck All life is made of cells
Schwaan Animals have cells
Schleiden Plants have cells

23. Cells Size
•Sizes on a microscope are measured in microns. A micron is one
millionth of a meter or 0.001 of a millimeter.
•They range in size
Largest cell = Ostrich egg
Smallest cell= .000001 microns Yikes-tiny!
Average cell size= .5-40 microns
(remember 1 micron = .001 mm)
•Size is restricted: Why? Most cells are small has to do with
simple geometry more than anything else: specifically the
relationship between surface area to volume as a cell gets bigger.

24. The undisputed largest extant bird egg on earth today is laid by an
ostrich. An average egg weighs about three pounds (1.4 kg), and is
roughly equivalent to about two dozen chicken eggs. It would take
approximately 40 minutes to hard-boil an ostrich egg. The yolk of
an ostrich egg is the largest cell by volume; however, nerve cells
from the spinal cord of a large hooved mammal may be nearly two
meters in length!

25. Highly magnified view (2000x) of A culture of rod-shaped
human pus showing white blood cells anthrax bacteria (Bacillus
(called neutrophils) with deeply-lobed anthracis). Some of the
purple nuclei. bacteria have divided by
fission (red arrow).

26. As the size of a cube
increases, the ratio of
the surface area to
volume gets smaller.
Why would this
surface area to
volume ratio impact
a cell?

27. Cells have an internal structure
• There are many different cells
• Obviously there is “stuff” inside them.
• Cells are classified into two groups
depending on how that “stuff” is organized.

28. Cell organelles
• Some cells contain organelles.
• Consider that we have internal parts called
organs.
• While some cells just have watery fluid
with molecules inside them (prokaryotic
cells,) others have well defined specialized
parts called organelles (little organs.) These
cells are called eukaryotic cells.

29. Types of cells
• PROKARYOTES • EUKARYOTES
-MORE ADVANCED
-UNICELLULAR
-ALL CELLS IN
-ARE THE LARGEST MULTICELLULAR
GROUP OF ORGANISMS ORGANISMS ARE
-SIMPLE STRUCTURE EUKARYOTES AND SOME
IN UNICELLULAR ORGAN.
-NO NUCLEUS
- HAVE NUCLEUS
-NO MEMBRANE BOUND -THESE HAVE MEMBRANE
ORGANELLES - BOUND ORGANELLES
APPEARED ABOUT 4 -COMPLEX INTERNAL
BILLION YEARS AGO- most STRUCTURE
primitive - APPEARED ABOUT 1
• EXAMPLE: bacteria BILLION YEARS AGO
& Blue green algae EXAMPLE: fish, oak
trees, humans,
paramecium

30. PROKARYOTIC CELLS
No membrane bound Bacteria cells are very small-
nucleus. Instead, DNA is in only a fraction of the size of an
a circular loop called a animal cell.
plasmid!
Prokaryotes feature 3 major shapes:
spheres, rods, spirochetes.

31. PROKARYOTIC CELLS
Bacteria serve as
decomposers, act in
the nitrogen cycle,
are agents of
fermentation, and
play an important
role in our own
digestive system.
But they can also
make us SICK! 

32. .
HOW THE EUKARYOTE
FORMED FROM THIS FIRST
BASIC PROKARYOTE…
Once upon a time (about one billion years ago), the first eukaryotic cell
came to be. There was a group of primitive bacteria going about their
business when along came a big hungry phagocyte, who ate one of the
bacterium. Mr. Phagocyte: Yum.
Bacterium: Excuse me.
Mr. Phagocyte: What?
Bacterium: You know, why don't
we join forces and I can help you
and you can help me and we can
become a 'eukaryotic' cell?
Whaddaya say?
Mr. Phagocyte: OK

33. PROKARYOTE EUKARYOTE
WITHOUT membrane bound WITH membrane
organelles bound organelles

34. PRO OR EUK
1. Snake cells EUK
2. Human cheek cells EUK
3. Venus fly trap plant cells EUK
4. Blue-green algae PRO
5. Fecal Coliform PRO
6. Salmon cells EUK
7. Salmonella Bacterium cells PRO

35. For now think of the cell as an independently functioning unit of life. In
order to perform the many specific tasks there must be many specific
parts. So we will come up with an ANALOGY- The Cell as the City.

36. THE CELL THE CITY
•Cell membrane is like the _________________
City limits, borders
because it determines what comes in and of
the cell/city
•The nucleus is like __________- a storage site
City hall
for all the cells information.
Land, air, and water
•The cytoplasm is like the __________________
in the city. They are the substances in the
cell that carry oxygen, proteins, carbs, and
other substances.
•The mitochondria is like a _____________.
Power plant
This is where nutrients are converted into
usable cellular energy.
•Ribosomes are the site where protein is put
together. Like the __________ of a city.
factories

37. •Endoplasmic reticulum are like ___________________________
Business district
because they are where the proteins, lipids, and carbohydrates (3 of
the big 4) are processed
•Golgi apparatus are like the _____________________. They are
Post office/UPS/FedEx
the parts that modify and package up the cellular materials before
being excreted out of the cell.
•Lysosomes and peroxisomes are the _______________________.
Waste removal/sewage plant
They store strong digestive enzymes (proteins.)
Lysosomes under the
Like a stack of pancakes microscope

38. •Chloroplasts are analogous to ________________________ found in
a solar Power plant
green plant cells and some protists. They convert sunlight into
cellular or (chemical) energy.
•Vacuoles are like the city’s water Supply/warehousesThey hold water
_________________.
and nutrients for the cell. Large central vacuoles usually just found
in plant cells
traffic patterns within the
•Centrioles are like the __________________________ which aid
cell
in cell/movement and division. Found mainly in animal cells.

39. Cell wall is analogous to ________________________________.
an outside city surrounding highway
It is found mainly in plants/fungi and provides support to the cell.
Chemical storage/refineries
Vesicles are like _____________________________ which hold
food and energy molecules for chemical reactions, similar to
vacuoles.
Cell analogy Project: Can you come up with a creative
analogy for cell organelles in a eukaryotic cell?

40. A little review…
What cell parts are primarily found in
PLANT cells?
CELL WALLS, CHLOROPLASTS AND LARGE
CENTRAL VACUOLES
What cell parts are primarily present in
ANIMAL cells?
CENTRIOLES

41. More review
LET’S FILL IN THE CHART BELOW WITH 1 WORD
ANSWERS.
CELL PART ONE WORD
FUNCTION
CELL
MEMBRANCE
GOLGI BODIES
VACUOLES
Click for
NUCLEUS answers
LYSOSOME

42. POSSIBLE CHART ANSWERS
CELL PART ONE WORD
FUNCTION
CELL regulator
MEMBRANCE
GOLGI BODIES packager
VACUOLES storage
NUCLEUS information
LYSOSOME digestion

43. Let’s look at some cells

47. CELL MOVEMENT
Plant cells
need to
move from
Cells need to move. Why? Turn to your
one plant to
another- like
table partner and come up with 3 types
pollen- so
that it too
of cells and why they might need to
can fertilize
another
move? plant for
reproduction
White blood cells
need to move
Sperm cells need to around the body to
“swim to the egg” to help fight
infection!
fertilize it!

48. How do cells move?
PLANT CELLS CAN NOT MOVE ON
THEIR OWN…THEY RELY ON THEIR
ENVIRONMENT TO MOVE…
EXAMPLES: air, wind, water moving
cells from one place to another.
JUST ANOTHER REASON WHY WE
NEED TO KEEP OUR RIVERS CLEAN
AND FLOWING!
Some animal cells rely on bodily fluids to
move them as well.

49. Animal cells move
•Cilia= many small hair like
structures around the
outside of the cell
•Flagella- long whip-like
extensions from cell.
Propeller-like.
Pseudopod- false foot
extension of cell membrane

50. LET’S EXPLORE
REAL CELLS
What might a cell look like under a microscope?
Will we see all the parts?
What might we see more often in plants than in
animals?

51. Let’s have a look!