Download CELLS: THE BASIC UNIT OF LIFE

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
Found cells in other organisms….
SAW “ANIMALCULES” IN
POND SCUM
ALSO SAW BLOOD CELLS
AND BACTERIA for the first time
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. Cytoplasm- the fluid
1. Cell
membrane-outer
covering
2. Organellessmall bodies in the
cytoplasm
3. DNA (genetic
material)
inside a cell along with all the cell’s
contents
All cells have a …
Small size
Smallest=bacteria
 Largest=ostrich egg
 how big animation

Two Kinds of Cells:
1. Cells without a nucleus

Called Prokaryotic cells

These can be either:
bacteria or archaea
 Are 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 prokaryotes
Smallest cells known
Live almost everywhere
No nucleus but DO have DNA

DNA is long and shaped like a twisted
rubber band (circular shaped)
No membrane-covered organelles
Do have ribosomes and cell wall
Brainpop
Archaea…
Same as bacteria except:
Ribosomes are different…..are more like
Eukaryotic ribosomes
 Cell wall and cell membranes are made
of different materials
 Many 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
Archaea
Are 10 times bigger than bacteria
Have a NUCLEUS
Have MEMBRANE –COVERED
ORGANELLES
Have 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 2
The Inside of a Eukaryotic
Cell
The “true” cell.
plants
animals
fungi
Fluency Chart…
Cell wall
ribosome
Golgi
Complex
vesicle
Mitochondrion
plural=mitochondria
Golgi Complex
Cell
membrane
lysosome
vesicle
E.R.
ribosome
Endoplasmic
reticulum
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 membrane
When 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
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
Cellular Digestion…
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?
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…(Small to big)
CELLS
TISSUES
ORGANS
ORGAN SYSTEMS
ORGANISM
Organism
Anything that can perform life processes
by itself
Euglena:
Organisms can be:
Unicellular-(single celled)
 Multicellular- (consists of many cells)

Larger size
Longer life
Specialization
Each type of cell has a special job
 Makes 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 3
Cells: The Basic Units of Life