B.Sc. Biochemistry II Cellular Biochemistry Unit 1 Basics of Cell

Cellular Biochemistry
Unit 1
Basics of Cell and cell membrane
B.Sc Biochemistry II

The Cell Theory States:
• As written by Rudolph Virchow (1821-1902):
– All living organisms are made of one or more cells.
– Cells are the basic units of structure and function in
all organisms.
– All cells come from previously existing cells.
– The activity of an entire organism depends on the
total activity of its independent cells.

Ancient Times
• Ancient peoples are always on
the look-out for ways that
organisms can be used by
them.
• They pass on their
understanding orally.
• Some civilizations support
“great thinkers” – and
philosophers, but they rarely
base their thoughts on
observation or experiments.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory

334 B.C.E - Aristotle
• Greek philosopher,
Aristotle, begins to observe
nature.
• He classifies all known
organisms as either a Plant
or Animal.
• He writes that living things
can arise spontaneously
from non-living matter.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1268 – 1st Eyeglasses
• Roger Bacon, an English
friar makes reference to a
pair of eye glasses.
• This means that glass is
being developed and used
in a way that makes it
easier to see small things.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
1

1500’s
• Most European’s think that
knowledge is unchangeable
and should not be
questioned.
• To find answers about
nature, they look to the
original teachings of
Aristotle.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1590 – 1st Microscope
• Zacharias Janssen, a Dutch
eyeglass maker, makes the
1st microscope by placing
two lenses on top of one
another to make extra-large
images.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
2

1600’s
• People start to question the
origins of life.
• Many begin to suggest that life
can only come from other
forms of life rather than
through spontaneous
generation (as was suggested
by Aristotle). This only took
about 2000 years!
• William Harvey says that
maggots do not come from
the meat itself but from tiny
eggs too small to be scene.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
William Harvey
English Physician
1578-1657

1665 – 1st Cells Seen
• Robert Hooke (1635-1703) publishes a
book that shows illustrations of tree bark
lining as seen through a simple compound
(2 lens) microscope.
He observed pieces of cork from the bark
of a cork tree under the microscope.
- His observations led him to coin the
word “cell.”
- “Cell”- means little rooms in Latin
- He compared the small boxes to the
small rooms that monks lived in
• Wrote and published “Micrographia”
• Known as the “English Father of
Microscopy”
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1667 – Species Defined
• John Ray (1627-1705)
defines a “species” as a set
of individuals that can
reproduce their own kind.
• The beginning of the end of
spontaneous generation!
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
William Harvey
English Physician
1578-1657 3

1668 – 1st Experiments about origins of maggots
• Francesco Redi (1626-1697)
conducts experiments to
prove that maggots do not
appear in meat if flies
cannot land on it!
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
William Harvey
English Physician
1578-1657
3

1674 – 1st Microscopic Beasties Seen!
• Anton van Leeuwenhoek
(1632-1723) reports being
able to see tiny beasties
(0.002 mm) using a simple
single-lens microscope.
• 1673: He looked at pond scum
under the microscope and
discovered small organisms he
called animalcules or little
animals (Protists)
- 1676: discovered bacteria
• 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
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
William Harvey
English Physician
1578-1657

1753 – Birth of Classification
• Carolus Linnaeus (1707-
1778) begins to show people
the great diversity of living
things by exploring methods
of classifying them into 5
main Kingdoms.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
4

1770 – Advancement of Microscopes
• Microscopes become
sturdier and easier to use.
• Flaws in glass production
still causes images to be
blurry and have coloured
halos.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
5

1800’s – Support for Science Grows
• Lots of interest in science
• Public lectures are popular
• The wealthy mount
expeditions to collect new
specimens
• The HMS Investigator goes
on a 5 year voyage of
discovery.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1809 – 1st Science Texts for Students
• Jane Haldimand (1769-1858)
writes textbooks for young
people to learn about
science.
• Terms such as “cell”,
“cellular system” and
“Cellular tissue” appear in
the book.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1820’s – Better Glass = Better Lens
• Microscope quality improves
with the production of
better glass.
• Many English companies
compete to produce the
best microscope.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
6

1825 – Book “Cells from Cells”
• Francois Vincent Raspail
(1794-1878) wrote a book
called (translated from Latin)
“Every cell is derived from a
preexisting cell”.
• This again puts to rest the
idea of spontaneous
generation.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1830 – Cells are studied
• Biology is becoming an
important science and the
body of knowledge is
growing, especially since the
improvement of
microscopes.
• Scientists begin to study the
cell extensively!
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
6

1831 – Nucleus of Cell Found
• Robert Brown (1773-1858) is
the 1st to consider the
nucleus as a regular part of a
living cell.
• The nucleus is still hard to
see though without the
invention of the electric light
for his microscope.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1838 – Plant cells!
• Matthias Jacob Schleiden
(1804-1881) makes the claim
“All plants are made of cells”.
• Cells are alive!
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
7

1839 – Animal cells!
• Theodor Schwann (1810-
1882) makes the claim “All
animals are made of cells”.
• “All living things are made of
cells”
• Cells are the basic building
blocks of life!
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1845 – Cell Basic Unit of Life
• Alexander Carl Heinrich
Braun (1805-1877) makes
the claim:
“The cell is the basic
unit of life”.
• Cells are made of
protoplasm enveloped
by a flexible membrane.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1850’s
• Biological knowledge
advances, especially in the
areas of medicine, botany
and zoology!
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1856 – Staining technique developed
• 18 year old, William Henry
Perkin (1838-1907) develops
a new purple dye for staining
cell parts making it easier to
see cell parts with a
microscope.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900
8

1858 – Article on Evolution
• Charles Darwin (1809-1882)
& Alfred Wallace (1823-
1913) read their article on
“Tendency of species to form
variations”.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1858 – Cell Theory Outlined
• Rudolph Virchow (1821-
1902) develops his Cell
Theory that is still largely
accepted today.
• He is known as the
“Father of Pathology.”
• Discovered that all living cells
come only from other living
cells
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

1860’s – The end of the “Spontaneous Generation” debate
• Louis Pasteur (1822-1895)
conducts a series of
experiments that once and
for all put to rest the idea of
spontaneous generation and
concluding that living
organisms do not arise from
non-living matter.
500 BCE
300 BCE
1000
1500
1600
1700
1800
1900

The Cell Theory
• Major Contributors:
• Matthias Schleiden
• Theodor Schwann
• Rudolph Virchow

The Cell Theory
The 3 Basic Components of the Cell Theory were now complete:
1. All organisms are composed of one or more cells. (Schleiden &
Schwann)(1838-39)
2. The cell is the basic unit of life in all living things. (Schleiden &
Schwann)(1838-39)
3. All cells are produced by the division of preexisting cells.
(Virchow)(1858)

Modern Cell Theory
• Modern Cell Theory contains 4 statements, in addition to the
original Cell Theory:
– The cell contains hereditary information(DNA) which is passed on from
cell to cell during cell division.
– All cells are basically the same in chemical composition and metabolic
activities.
– All basic chemical & physiological functions are carried out inside the
cells.(movement, digestion,etc)
– Cell activity depends on the activities of sub-cellular structures within
the cell(organelles, nucleus, plasma membrane)

How Has The Cell Theory Been Used?
• The basic discovered truths about cells, listed in the
Cell Theory, are the basis for things such as:
– Disease/Health/Medical Research and Cures(AIDS, Cancer,
Vaccines, Cloning, Stem Cell Research, etc.)

Discoveries
Since the Cell
Theory

ENDOSYMBIOTIC THEORY
• In 1970, American biologist, Lynn
Margulis, provided evidence that
some organelles within cells were
at one time free living cells
themselves
• Supporting evidence included
organelles with their own DNA
• Chloroplast and Mitochondria

Review Facts About
Living Things

What Are the Main Characteristics
of organisms?
1. Made of CELLS
2. Require ENERGY (food)
3. REPRODUCE (species)
4. Maintain HOMEOSTASIS
5. ORGANIZED
6. RESPOND to environment
7. GROW and DEVELOP
8. EXCHANGE materials with surroundings (water,
wastes, gases)

Characteristics of All Cells
• A surrounding membrane
• Protoplasm – cell contents in thick fluid
• Organelles – structures for cell function
• Control center with DNA

Cell Size and Types
• Cells, the basic units of organisms, can only be
observed under microscope
• Three Basic types of cells include:
Animal Cell Plant Cell Bacterial Cell
9

Cell Size
Question:
Are the cells in an elephant bigger,
smaller, or about the same size as
those in a mouse?

Factors Affecting Cell Size
• Surface area (plasma membrane surface) is
determined by multiplying length times
width (L x W)
• Volume of a cell is determined by multiplying
length times width times height (L x W x H)
• Therefore, Volume increases FASTER than the
surface area

Cell Size
• When the surface area is no longer great
enough to get rid of all the wastes and
to get in enough food and water, then
the cell must divide
• Therefore, the cells of an organism are
close in size

Cell Size
Question:
Are the cells in an elephant bigger,
smaller, or about the same size as
those in a mouse?
About the same size, but …
The elephant has MANY MORE cells than a
mouse!

Multicellular Organisms
• Cells in multicellular organisms often
specialize (take on different shapes &
functions)

Cell Specialization
• Cells in a multi-cellular
organism become
specialized by turning
different genes on and
off
• This is known as
DIFFERENTIATION
45

Organization Levels of
Life
Atoms to Organisms

LEVELS OF ORGANIZATION
Nonliving Levels:
1. ATOM (element)
2. MOLECULE (compounds like carbohydrates
& proteins)
3. ORGANELLES (nucleus, ER, Golgi …)

LEVELS OF ORGANIZATION
Living Levels:
1. CELL (makes up ALL organisms)
2. TISSUE (cells working together
3. ORGAN (heart, brain, stomach …)
4. ORGAN SYSTEMS (respiratory, circulatory …)
5. ORGANISM

ATOMS  MOLECULES  ORGANELLES
Nonliving Levels

CELLS – life starts here TISSUES – Similar cells working together
Living Levels



ORGANS
ORGAN
SYSTEMS ORGANISM
Different tissues
working together
Different organs
working together
 
More Living Levels

Cell Types
• Prokaryotic
• Eukaryotic

Prokaryotes – The first Cells
• Cells that lack a nucleus or
membrane-bound organelles
• Includes bacteria
• Simplest type of cell
• Single, circular chromosome
• First cell type on earth
• Cell type of Bacteria and
Archaea
• Nucleoid = region of DNA
concentration

Eukaryotes
• Cells that HAVE a nucleus
and membrane-bound
organelles
• Includes protists, fungi,
plants, and animals
• More complex type of cells

Eukaryotic Cell
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles

Similarities between plant cells and
animal cells
Both have a cell membrane
surrounding the cytoplasm
57
Both have a nucleus
Both contain mitochondria

Differences between plant cells and
animal cells
58
Animal cells Plant cells
Relatively smaller in
size
Irregular shape
No cell wall
Relatively larger in
size
Regular shape
Cell wall present

Differences between Plant Cells and
Animal Cells
59
Animal cells Plant cells
Vacuole small or absent
Glycogen as food
storage
Nucleus at the center
Large central vacuole
Starch as food storage
Nucleus near cell wall

CELL WALL
• Because a lipid–protein plasma membrane of less
than 10-nm thickness can be expected to offer
only minimal protection for a cell’s contents, it is
not surprising that “naked” cells are extremely
fragile structures.
• The cells of nearly all organisms other than
animals are enclosed in a protective outer
envelope.
• Protozoa have a thickened outer coat, whereas
bacteria, fungi,and plants have distinct cell walls.

• The cell wall is the tough, usually flexible but
sometimes fairly rigid layer that surrounds some
types of cells.
• It is located outside the cell membrane and
provides these cells with structural support and
protection, and also acts as a filtering
mechanism.
• A major function of the cell wall is to act as a
pressure vessel, preventing over-expansion when
water enters the cell. They are found in plants,
bacteria, fungi, algae, and some archaea. Animals
and protozoa do not have cell walls.

• The materials in a cell wall vary between species, and in
plants and fungi also differ between cell types and
developmental stages.
• In plants, the strongest component of the complex cell wall
is a carbohydrate called cellulose, which is a polymer of
glucose. In bacteria, peptidoglycan forms the cell wall.
• Archaean cell walls have various compositions, and may be
formed of glycoprotein S-layers, pseudopeptidoglycan, or
polysaccharides.
• Fungi possess cell walls made of the glucosamine polymer
chitin, and algae typically possess walls made of
glycoproteins and polysaccharides.
• Unusually, diatoms have a cell wall composed of silicic acid.
Often, other accessory molecules are found anchored to
the cell wall.

References
• Images references:
1. http://commons.wikimedia.org/wiki/File:Goya_Self_portrait_with_spectacles_%28Musee_Goya_
Castres%29.jpg
2. http://micro.magnet.fsu.edu/primer/museum/janssen.htmla
3. http://papapipi.com/spontaneous-generation-vs-biogenesis/
4. http://www.desktopclass.com/education/fafsc/two-to-five-kingdom-classification-systems-f-sc-
biology.html
5. www.antique-microscopes.com/kellner/kellner1.html
6. http://zeisshistoricasociety.org/microscopes/
7. http://www.kidsbiology.com/biology_basics/cells_tissues_organs/cell_history_discovery4.php
8. http://en.wikipedia.org/wiki/White_blood_cell
9. http://papapipi.com/tag/plant-cell
• Reading references:
• Cell and Molecular Biology, 6th Ed By Karp -

B.Sc. Biochemistry II Cellular Biochemistry Unit 1 Basics of Cell

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B.Sc. Biochemistry II Cellular Biochemistry Unit 1 Basics of Cell