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Cells
Cell Discovery
1665
• Robert Hooke: Around the time of Newton
– discovered the cell while looking through a
microscope
– Saw dead cells of a cork plant
– Called them cells because they related to his
‘cell’: the room he lived in at the monestary
Discovery of Cells
1673
• Leeuwenhoek – first biologist to see living
organisms with microscope
• Discovered single – celled organisms
called prokaryotes
Discovery of Cells
• Other scientist have contributed to the
recognition of cells!!!
• Scientist such as Leeuwenhoek,
Schleiden, Schwann, and Virchow all
studied cells
Discovery of Cells
• Schleiden – examined plant tissue
- said all plants are composed of cells
• Schwann – examined animal tissue
- said they must contain cells as well
• Virchow - said cells come from existing
cells
• All these scientist’s work led to the cell
theory!!!!
Cell Theory
150 Years Later
1. All living things are composed of one or
more cells
2. Cells are the basic units of structure and
function in an organism
3. Cells come only from the reproduction of
existing cells
Microscopes
Compound Light Microscopes
• Uses glass lenses and light to
produce a magnified image
• Can magnify a small image to
almost 2000x its size!!!
Revolving
nosepiece
Eyepiece
Body tube
Objective
Clip
Condenser
Iris diaphragm
Coarse adjustment
Fine adjustment
Arm
Stage
Condenser control knob
Mirror
Base
8
Hierarchy of Organization
• Remember two characteristics of life
1)Most contain cells
2)Can be highly organized
Cells are small units with special functions!!!
They will work together to carry out these
special functions.
Hierarchy or Levels of Organization
Cells
Tissues
Organ
Organs
System
Organisms
Cell Diversity
• 200 different types of cells in our body
• Most are microscopic
• Few can be seen without a microscope
– Frog egg cells
– Giraffe nerve cell in leg (2 meters long)
Cell Shapes
• Why are cells shaped differently?
Shape Determines Function!!
Cell Shapes
• What does a nerve
cell look like?
• How does a skin cell
appear?
Cell Shapes
• What about a white blood cell?
• Why??
Shape Determines Function!!
Why are Cells so Small?
• Surface area to volume ratio!!
– As a cell gets larger, it adds volume faster
than it adds surface area
– (In English) The bigger the inside, the less
area there is on the outside for stuff to pass
through
• Modeling Activity
Internal Organization
• Cells have structures called organelles
– Perform specific functions in the cell
– Like miniature organs
Cell Types
• There are two types of cells
• 1) Prokaryotic - means no true nucleus
- No membrane –bound organelles
- Smaller in size
Example: Bacterial Cells
• 2) Eukaryotic – means true nucleus
- Membrane – bound organelles
- Larger in size
Example: Plants, Animals, Fungi
Prokaryotic Cells
• They have a cell (plasmsa) membrane and a cell
wall
• Nucleoid – Region where DNA is contained
• Other organelles such
As ribosomes
** REMEMBER NO
MEMBRANES WILL BE
AROUND ANY
ORGANELLES FOUND
IN PROKARYOTIC CELLS
Eukaryotic Cells
• Two Types
• 1) Animal Cells
Cells
2) Plant
Organelles
• Inside these cells are organelles .
• What is an organelle??????
• An organelle is are internal structure within
the cell that performs certain functions!!
• Each organelle has a special function and
each organelle is unique in shape.
• Where are they found? In the cytoplasm of
the cell
Cytoplasm
• A jelly-like substance found in the cell
• Where reactions will occur in a cell
• Where organelles can be found in a cell
Cytoplasm
Animal Cell Organelles
• Cytosol: Soup of the cell
– “Bathes” other organelles with nutrients
• Cell membrane: Gatekeeper
– Controls what goes in or out of the cell
Animal Cell Organelles:
Endoplasmic Reticulum
• Endoplasmic Reticulum – E.R.
Tube-like canals
- Two Types of E.R.
1) S. E. R. –Smooth Endoplasmic Reticulum
2) R. E. R. – Rough Endoplasmic Reticulum Smooth – lacks ribosomes – makes proteins and
lipids
Rough – has ribosomes on it – makes protein to
be carried out the cell
Mitochondria
Mitochondria
The “powerhouse” of the
cell. This is where
cellular respiration
occurs and where energy
is made!!!
Golgi Apparatus or Bodies
•
-
Golgi Apparatus – or called golgi bodies
They are sac-like structure
Will receive proteins from the E.R.
Their main function is to package and ship the proteins
out of the cell. (UPS Center)
Lysosomes
Lysosomes – contain
digestive enzymes that will
breakdown unwanted
waste from the cell.
-Will breakdown other cell
parts that are not needed
and breaks down food
-Police force and Recycle
center
Cell Types
• Prokaryotic
- No true nucleus
- No membrane –bound organelles
- Smaller in size
• Eukaryotic
- True nucleus
- Membrane – bound organelles
- Larger in size