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Development of Cell Theory
Prokaryotic and Eukaryotic cells
Structure and function of cell structures and organelles
CELL THEORY
 All living things are made up of one
or more cells and of products of cells
 The cell is the simplest unit of life
 All cells are produced from pre
existing cells (idea of biogenesis)
Development of cell Theory
1665 : Robert Hooke
 made a simple microscope
 examined cork cells and
described them as “a great
many little boxes or cells” Hooks microscope and the cork
tissue examined
The work continued
Van Leeuwenhoek’s Microscope
1674: Anton van Leeuwenhoek
 used microscope to examine
material removed from his
teeth
 he described the first bacteria
Van Leeuwenhoek’s drawings of what
he saw in teeth scrapings
200 years of investigation
into cells followed
1838 - Schleiden
(Botanist)
suggested cells were
the basic building
blocks of all plant
matter
1839 - Schwann
suggested all animals
were aggregates of
cells
1858 - Virchow
proposed that
new cells come
from preexisting
cells
1862 - Pasteur
“disproved”
spontaneous
generation and
supported
Virchow’s theory of
Biogenesis
Pasteur’s experiment
supporting Biogenesis
He then boiled the broth, killing any microorganisms that were present. If the
To allowofair
to enter the
and atshould
the same
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prevent
air-borne
bacteria
theory
biogenesis
wasflasks
valid there
be no
growth
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sterilized
from gaining entry, Pasteur bent the necks of his flasks after he added broth.
broth.
Features of All living Cells
 A membrane separates the inside of the cell
from the external surroundings
 There is a jelly like substance(cytosol) inside
the cell
 There is genetic material inside the cell at
some point in the life of the cell
 All have RIBOSOMES that make protein using
the code in genetic material
Cell types
All cells fall into one of two broad categories
ALL CELLS
Prokaryotic
Eukaryotic
Prokaryotic organisms
 Include bacteria and
cyanobacteria
(KINGDOM
MONERA)
 Lack a membrane
bound nucleus and
other membrane
bound organelles
 Single celled
Cell structures present
• Cell wall 
• Cell membrane 
• Ribosomes 
• Cytosol 
• DNA 
• sometimes
cilia/flagella 
TEM of a Bacterial Cell
(Transmission Electron Micrograph)
Eukaryotic Cells
Eukaryotic cells
 Include animal cells, plant cells, fungal
cells, and protist cells
 All have a membrane bound nucleus and
other membrane bound organelles
Eu: True
Caryo: nucleus
Plasma Membrane
 LOCATION:
Surrounding the cytosol
 DESCRIPTION:
 a phospolipid bilayer with embedded
proteins
 FUNCTION:
 A semi-permeable barrier
 Controls the entry and exits of substances
to and from the cell
MORE ON THIS LATER
Outside cell
Phospholipid
bilayer
cholesterol
Inside
cell
Integral (Transmembrane) protein
Integral membrane
protein
TEM of plasma (cell) membrane
ribosome
Plasma membrane
Cell wall
Nucleus
FUNCTION:
 Controls cellular
metabolism and
reproduction by….
 controlling what
proteins are
synthesised*
Nuclear Membrane…...
Inner membrane
nucleus
Nuclear pores
Outer membrane
Nuclear Membrane
 LOCATION:
surrounding the nucleus
 DESCRIPTION:
 double membrane
 nuclear pores
Nuclear Membrane…...
FUNCTION:
 Holds nuclear
contents in place
 Controls movement
of chemicals between
the nucleus and the
cytoplasm
Cytosol
 LOCATION:
inside cell, bound by the plasma membrane
 DESCRIPTION:
 the fluid and semi fluid matrix of the cytoplasm
 includes the cytoskeleton
 contains many enzymes
Cytosol
FUNCTION:
 suspension of organelles
 cell shape
 many chemical reactions occur here
 Distributes materials by diffusion
Cytoplasm
 LOCATION:
inside cell
 DESCRIPTION:
 the jelly like cytosol and the
organelles suspended within it .
Includes the plasma(cell) membrane
 does not include the nucleus
Cytoplasm
FUNCTION
 many cellular reactions occur in the
components of the cytoplasm
What
are these
Mitochondia
Intermembrane space
cristae
Enzyme complex
matrix
Outer
membrane
Inner membrane
Mitochondria(p)
Mitochondrion (s)
STRUCTURE CONTINUED
 Important metabolic enzymes
located within
FUNCTION
 Are the site of aerobic cellular respiration
(krebs cycle), producing 95% of the ATP
required by a Eukaryotic cell.
Ribosomes
Enlarged Ribosome
ribosome
FUNCTION
 The site of protein
synthesis …..
 Here amino acids are
linked together to
form proteins (using
the information
encoded in the DNA to
do so)
Smooth Endoplasmic
Reticulum (ER)
 LOCATION:
suspended in the cytosol often connected to
the nuclear membrane and sometimes to cell
membrane
 DESCRIPTION:
 network of flattened membranes
forming a system of channels
 contains enzymes for lipid metabolism
Smooth (ER)
FUNCTION:
 associated with lipid
synthesis
 transport of materials
made within the cell
around the cell
Smooth ER
Rough Endoplasmic
Reticulum(ER)…...
 LOCATION:
suspended in the cytosol often connected to
the nuclear membrane and sometimes to cell
membrane
 DESCRIPTION:
 network of flattened membranes
forming a system of channels
 ribosomes embedded into membrane
Rough (ER)
FUNCTION
 transportation of
proteins formed by the
ribosomes to other
parts of the cell
 intracellular storage
Rough ER
What Golgi
can you
see here?
body
Golgi apparatus showing vesicles
forming
vesicles
mitochondria
golgi body Trans view showing
vesicles budding off
golgi
body
vacuole
Golgi Body
FUNCTION:
 storage, alteration and packaging of
substances made within the cell into vesicles
for export outside of the cell
 plentiful in secretory cells of eukaryotes
Secretion
 Substances made on the ribosomes of
rough ER are transported through
channels of ER to the golgi body
 Substances are packaged into vesicles and
transported out of the cell by exocytosis
Vesicle
FUNCTION:
 transport of materials from inside the cell to
outside, or from outside to inside
 storage (eg small fat droplets)
 Lysosomes are a vesicle with specialized
structure and function
Lysosome
FUNCTION
 Intracellular removal of damaged organelles
or of pathogens
 Role in cell death
Vacuole
FUNCTION:
 Storage of water, minerals and some organic
compounds
 plays a role in creating turgid state of plant
cells
 In fresh water protocts contracile vacuoles
help maintain fluid balance
Vacuole
Cell wall
 LOCATION:
surrounding the cell(plasma) membrane of
plant cells, and bacteria
 DESCRIPTION:
 a rigid structure
 composed of cellulose and some
lignin (plant cell walls only)
Cell wall
FUNCTION:
 strength and support
 prevents cells from bursting
Cell wall
 LOCATION:
surrounding the cell(plasma) membrane of
plant cells, and bacteria
 DESCRIPTION:
 a rigid structure
 composed of cellulose and some
lignin (plant cell walls only)
PLASTIDS
 plastids are found within some plant cells
 animal cells lack plastids
There Are Three Kinds
 CHLOROPLASTS
 CHROMOSPLASTS
 LEUCOPLASTS

Amyloplast(starch)
stroma
starch
granule
granum
thylakoid
membrane
Inner
membrane
TEM of a chloroplast
outer
membrane
Chloroplast
FUNCTION:
 absorb sunlight energy
 photosynthesis occurs here: glucose is
synthesised from Carbon Dioxide and water
Chromoplast
FUNCTION:
 to make particular parts
of plants colourful
Leucoplast (Amyloplast)
FUNCTION:
 Storage of starch
Structures found in plant cells
but not in animals cells
 In all plants cells
 Cell wall
 Large vacuole
 In some plant cells
 plastids
Cytoskeleton
FUNCTION:
 Strength and support
 Movement of cellular structures and materials
Cilia
Flagella
Cilia and flagella …...
FUNCTION:
 locomotion
 creating current to move materials in a
desired direction
Cilia and flagella
PRESENT IN:
 PROKARYOTIC
CELLS?
YES (flagella)
 PLANT CELLS?
YES (rare)
 ANIMAL CELLS?
YES
Cell Theory Rap
Listen close to the story I tell.
It's the rapping story of the living cell.
It's a happy tune that's sort of cheery.
About a real tough topic called the cell theory.
All animals, plants, and protists too,
Are made of cells with different jobs to do.
They're the basic units of all organisms,
And I hope by now you got the rhythm.
It all started with one dude named Hooke.
Who at some cork cells took a look.
He used a scope and took his time.
'Cause a cell is small and thinner than a dime.
Say 1, 2, 3, 4,
Are you ready to learn some more?
The animal cell has many parts,
And you must know each one by heart.
Like the farmer man in the dell.
The nucleus controls the cell.
it gives the orders -- kind of like a brain.
And it's protected by a nuclear membrane.
Around the cell, you'll find another "skin,"
The cellular membrane holds the whole cell in
But its job isn't simple there's no doubt,
It lets some particles go in and out.
Now please don't lose your science enthusiasm,
Listen to the story of the cytoplasm.
All around the cell this thick fluid does go,
But in the nucleus it will not flow.
And don't forget those ribosomes This is where proteins come from.
These protein factories are so small, you'll agree,
You need an electron microscope to see.
Just when you thought you weren't having any fun,
Along comes the endoplasmic reticulum.
These tubelike structures serve as a track,
To carry stuff to the membrane and back.
Now have you ever seen any doughnuts without holes?
In a cell, they're called vacuoles.
They're filled with stuff like H2O
And they carry food so the cell can grow.
Las of all, but not the very least,
Mitochondria - mighty cellular beasts,
Since they turn sugars into energy so well,
We call them the powerhouse of the cell.
Now my friend, you know it well,
The unforgettable story of the living cell.
"Science World"
10-5-90