cell theory

1. CELL
THEORY

13. SOME RANDOM CELL FACTS
•The average human being is composed of
around 100 Trillion individual cells.
•It would take as many as 50 cells to cover
the area of a dot on the letter “i”

14. IMPORTANT EVENTS
IN THE DISCOVERY
OF THE CELL AND
THE DEVELOPMENT
OF THE CELL
THEORY…..

15. MICROSCOPE
• In the first century BC, Romans were able to
make glass
• During the 12th century, Salvino D’Armate
made a piece of glass fit over one eye
• The expanded use of lenses in eyeglasses in
the 13th century probably led to wider
spread use of simple microscopes (magnifying
glasses) with limited magnification.

16. MICROSCOPE
• Compound microscope first appeared in Europe in 1620.
• Extensive microscopic study was done by Anton van
Leeuwenhoek, a draper who took the interest in
microscopes after seeing one while on an apprenticeship in
Amsterdam in 1648.
• Carl Zeiss, a German engineer who manufactured
microscopes, began to make changes to the lenses used.
But the optical quality did not improve until the 1880s
when he hired Otto Schott and eventually Ernst Abbe.

17. 1665 – ROBERT HOOKE
• Observed cells in cork.
• Coined the term "cells”.
• Book – Micrographia with 60 observations
• Thin slices of bottle cork – “cells”
• Latin “Cella” – small room
• “Cellulae” – six sided cell of honeycomb
• Also observed mold, bluish in color, found on
leather with no “seeds”
• Spontaneous generation – Aristotle

19. 1673 – ANTON VAN LEEUWENHOEK
• Used a handmade microscope to observe
pond scum & discovered single-celled
organisms
• He called them “animalcules”
• He also observed blood cells from fish, birds,
frogs, dogs, and humans
• Therefore, it was known that cells are found in
animals as well as plants

21. 1827-33 – ROBERT BROWN
• noticed that pollen grains in water jiggled
around called “Brownian motion”
• discovered the nucleus
• Henri Dutrochet – stated that:
 The cell is the fundamental element of
organization;
 Cells were not just a structural unit, but
also a physiological unit.

22. • In 1804, Karl Rudolphi and J.H.F. Link were
awarded the prize for “solving the problem of
the nature of cells”.
• They were the first to prove that cells had
independent cell walls by the Königliche
Societät der Wissenschaft (Royal Society of
Science), Göttingen.
• Before, it had been thought that cells shared
walls and the fluid passed between them this
way.

24. 150-200 YEAR GAP?
• Between the Hooke/Leuwenhoek discoveries and
the mid 19th
century, very little cell
advancements were made.
• This is probably due to the widely accepted,
traditional belief in Spontaneous Generation.
• Examples:
• Mice from dirty clothes/corn husks
• Maggots from rotting meat

25. 19TH
CENTURY ADVANCEMENT
•Much doubt existed around Spontaneous
Generation
•Conclusively disproved by Louis Pasteur
+
= ?

26. 1839 – MATTHIAS JAKOB SCHLEIDEN
• A botanist who
concluded that all plants
are made of cells.
• He claimed this theory as
his own,
though Barthelemy
Dumortier had stated it
years before him.

27. 1839 – THEODOR SCHWANN
• A zoologist who concluded that all
animals are made of cells.

28. 1855 – RUDOLPH VIRCHOW
•A physician who did
research on cancer cells
and concluded “Omnis
cellula e cellula”.
•“All cells are from other
pre-existing cells.”

29. •However, the idea that all cells come from pre-
existing cells had in fact already been proposed
by Robert Remak.
•Remak published observations in 1852 on cell
division, claiming Schleiden and Schwann were
incorrect about generation schemes.
•He instead said that binary fission, which was
first introduced by Dumortier, was how
reproduction of new animal cells were made.

30. THE CELL THEORY
(OLD)
1. All living organisms are composed of
one or more cells.
2. The cell is the most basic unit of life.
3. All cells arise only from pre-existing
cells.

31. THE CELL THEORY
(MODERN)
1. Energy flow occurs within cells.
2. Heredity information (DNA) is
passed on from cell to cell.
3. All cells have the same basic
chemical composition.

32. INTERPRETATIONS
•All known living things are made up of one or
more cells.
•All living cells arise from pre-existing cells by
division.
•The cell is the fundamental unit of structure and
function in all living organisms.
•The activity of an organism depends on the total
activity of independent cells.

33. INTERPRETATIONS
•Energy flow (metabolism and biochemistry)
occurs within cells.
•Cells contain DNA which is found specifically in
the chromosome and RNA found in the cell
nucleus and cytoplasm.
•All cells are basically the same in chemical
composition in organisms of similar species .

34. HOW SMALL CAN A
CELL BE?
Mycoplasmas - bacteria that are 0.1 to 1.0 mm.
(1/10 the size of regular bacteria).
Note: 1.0 mm = one millionth of a meter

35. For a clearer understanding of the
lesson, watch the video clip:
https://www.youtube.com/watch?v=4Op
BylwH9DU&t=3s

36. Group Activity #1: Making
A Timeline
Directions: Each group will be given an
idea / template about making a
timeline but creativity is very much
welcome. You need to bring the
materials.

37. INDEPENDENT LEARNING (GB1)
Directions: Answer the following activities on your
textbook:
What Have I Learned So Far?”, page 4, 7, & 11; and
Reflect Upon, page 5.
Write your answers on your book.

38. Making A Timeline
Big Book