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CELLS: THE BASIC UNIT OF LIFE
Some Cell Fun Facts
You can grow heart cells in a petri dish. Humans have an estimated 10 trillion cells. The largest known cell is an unfertilized ostrich egg cell. The word cell comes from the Latin word cellula, meaning, “small room”. One single cell contains two meters of DNA. Humans shed and re-grow outer skin cells about every 27 days.
Cells Discovered in 1665
Why didn’t we know about cells before this?
Robert Hooke’s microscope:
Section One: The Diversity of Cells
Part 1:The Discovery of Cells 1665
Robert Hooke
First person to describe cells
Also looked at feathers, fish scales, and eyeballs of house flies
Mostly looked at plants and fungi (these things have cell walls)- makes them easy to see
1673 ANTON van LEEUWENHOEK
SAW “ANIMALCULES” IN POND SCUM
ALSO SAW BLOOD CELLS AND BACTERIA for the first time
Found cells in other organisms….
200 Years Later…
1838
Matthias Schleiden, a German scientist said….all plant parts are made of cells
One year later, Theodor Schwann, a German scientist that studied animals stated that all animal tissues are made of cells
1858 Rudolf Virschow
Said that all cells form only from other cells
THE CELL THEORY:
1. ALL ORGANISMS ARE ONE OR MORE CELLS
2. CELL IS THE UNIT OF ALL LIFE
3. All cells come from existing cells
4 Parts found in all Cells
4 Parts found in all Cells
1. Cell membrane-outer covering
2. Organelles- small bodies in the cytoplasm
3. DNA (genetic
material)
4. Cytoplasm- the fluid
inside a cell along with all the cell’s contents
Small sizeSmallest=bacteriaLargest=ostrich egg how big animation
All cells have a …
Two Kinds of Cells:
1. Cells without a nucleus Called Prokaryotic cells
These can be either:bacteria or archaeaAre super small in size
2. Cells with a nucleus Called Eukaryotes-
(these are the cells in plants, animals and fungi)
1. Cells without a nucleus Called Prokaryotic cells
These can be either:bacteria or archaeaAre super small in size
2. Cells with a nucleus Called Eukaryotes-
(these are the cells in plants, animals and fungi)
PROKARYOTIC CELLS
Bacteria, and Archaea
NO NUCLEUS
NO MEMBRANES AROUND
ORGANELLES
CIRCULAR DNA(looks a little like a rubber band)
Bacteria
Most common prokaryotesSmallest cells knownLive almost everywhere No nucleus but DO have DNADNA is long and shaped like a twisted
rubber band (circular shaped)
No membrane-covered organellesDo have ribosomes and cell wall
Brainpop
Archaea…
Same as bacteria except:Ribosomes are different…..are more like
Eukaryotic ribosomesCell wall and cell membranes are made
of different materialsMany live in Bizarre environments!
Ex. heat-loving, salt-loving, methane-making archaea
SURFACE TO VOLUME RATIO:
ORGANISMS NEED SMALL CELLS TO KEEP THE RIGHT SURFACE TO VOLUME RATIO
IF A CELL GROWS TOO BIG, THERE WON’T BE ENOUGH OPENINGS IN THE SURFACE TO LET MATERIALS IN AND OUT !
EUKARYOTIC CELLS(our cells)
(ALL CELLS) EXCEPT bacteria and ArchaeaAre 10 times bigger than bacteriaHave a NUCLEUSHave MEMBRANE –COVERED ORGANELLESHave LINEAR DNA found inside a nucleus
Really important cell vocab:CELLULOSE- tough stuff in plant
cell walls
ATP- the “energy molecule” for a cell, (is like gasoline for a car)
DNA- instructions for the cell
PHOSPHOLIPIDS- the stuff all membranes are made of
Section 2The Inside of a Eukaryotic
Cell
The “true” cell.
plants animals fungi
Cell wall ribosome Mitochondrionplural=mitochondria
Golgi Complex
vesicle Golgi Complex
Cell membrane
lysosome vesicle
E.R. ribosome Endoplasmic
reticulum
Fluency Chart…
Plant Cells
Video:
CELL WALL
IN PLANT CELLS (and algae) ONLY
Made of a hard material called Cellulose
Provides strength and support to the cell membraneWhen you look at dried hay, sticks and wooden boards you are seeing the cell walls of dead plant cells!
PLANT CELL WALL PICTURES:
CELL MEMBRANE
All cells are covered by this
Is formed by phospholipid molecules
Allows nutrients in
Allows waste products out:
Cytoskeleton
A web of proteins in the cytoplasm that acts as a muscle and a skeleton. It helps a cell retain its shape and moves organelles around.
NUCLEUS:
Library, or Town center
Stores the DNA
Has all the “secret info” for the organism
RIBOSOMES:
SMALLEST of all ORGANELLES (THE DOTS) ON THE E.R.
(only organelle without a membrane)
Act like factories for making proteins
MITOCHONDRIA:
Power plants…release energy for the cell
Make the ATP ATP Used in all cell ( activities)
VACUOLE:
Is really big in plant cells
Small in animal cells
Serves as a water storage compartment
CHLOROPLASTS:(plant cells only!)
:
•Contains chlorophyll
•Captures sunlight to make food (sugar) used by mitochondria
•Makes plants appear green
GOLGI COMPLEX:
FedEx Delivery
Gets rid of things inside the cell
Shipping and Handling
LYSOSOMES:
Contain digestive enzymes
Clean-up/ destroy cell waste, sometimes called the recycling center
Can act as security to protect the cell from invaders
Sanitation company?
Cellular Digestion…
Mainly in animal cells
ENDOPLASMIC RETICULUM (ER)
Post office, delivery system, tunnel system
Makes lipids for membranes, processes and transports proteins
CELL: ER
Cytoplasm
VESICLES:
Membrane –covered compartments inside the cell
Animal cells: human cheek cells
Scientists believe that mitochondria and chloroplasts originated as a prokaryotic cell that was “eaten” by larger cells. They ended up surviving inside.
EVIDENCE?•Both have two membranes
•Have a) ribosomes and b) circular DNA
•Same size as bacteria
•Divide like bacteria
Sec.3: The Organization of Living Things…
CELLS
TISSUES
ORGANS
ORGAN SYSTEMS
ORGANISM
(Small to big)
Organism
Anything that can perform life processes by itself
Organisms can be:Unicellular-(single celled)Multicellular- (consists of many cells)
Euglena:
Larger size
Longer life
SpecializationEach type of cell has a special jobMakes the organism more efficient
Structure and Function
In an organism, structure and function are related.
Example: Alveoli air sacs in the lungs:
See fig. 4 p.79
End of Ch 3Cells: The Basic Units of Life
End of Ch 3Cells: The Basic Units of Life
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