Transcript Surface Area - Ms. Sanderson`s Science Room

Cells: The Basic
Unit of Life
The Diversity of
Cells
section 1
Cell: basic building block
of life
I. Cells and Cell Theory
A. Robert Hooke
first person to describe cells
in 1665, built a microscope
discovered box like structures in cork
named them cells- "little rooms"
these cells were the outer layer of
dead
cork cells
B. Discovered differences between cells
Hooke looked at slices of live plants
saw 'juicy' cells
Hooke also looked at feathers, fish
scales
and eyes of houseflies
Also continued looking at live plants and
fungus
Discovered plants and fungus have cell
walls
made them easy to see
Animal cells do not have a cell wall
C. Finding Cells in Other Organisms
Anton van Leeuwenhoek
Dutch merchant
In 1673, made his own microscope
and
looked at pond scum
saw small organisms in the water
named them animalcules -"little
animals"
Today we call them protists
single celled organisms
Leuwenhoek also looked at animal blood
fish, birds and frogs= oval blood cells
humans and dogs = round blood cells
first to look at bacteria
discovered yeast is a single cell organism
D. Cell Theory
almost 200 years passed before scientists
concluded all living things have cells
Matthias Schleiden
plants- said they are made of cells
Theodore Schwann
studied animals- said they are made of cells
Schwann wrote the first two parts of the
Cell Theory
1. All organisms are made of
cells
2. The cell is the basic unit of life
In 1858, Rudolf Virchow, a doctor stated
cells could form only from other cells
This was added to the cell theory
3. All cells come from existing cells
II. Cell Size
A. Most cells are too small to see
without a microscope
50 cells
B. A few large cells
largest cell is an yolk of an
egg
can be this size because
it
doesn't have to take in
more
nutrients
C. Many small cells
There is a physical reason why cells
are
small
Cells take in food and get rid of waste
through their outer surface
(cell membrane)
As a cell grows it needs more food and
produces more waste
If a cell becomes to big, it cannot take
in
enough food or pump out enough
The area of the cell's surface and its volume
limit the size of the cell
called the surface area to volume
ratio
ratio = Surface Area ( outside covering)
volume ( whole inside)
III. Parts of a cell
A. Common parts
cells have different shapes and
sizes
do different functions
have parts in common
B. Cell Membrane and
Cytoplasm
all cells are surrounded by
a cell membrane
protective layer/ acts as barrier
separates cell from environment
controls materials moving in and
out of cell
cells also have a fluid
fluid and contents are called
cytoplasm
C. Organelles
are structures that perform specific
functions within the cell
carry out life processes
different cells have different
organelles
most have membranes
some float in the cytoplasm; others
are
attached to the membrane or
other
organelles
D. Genetic Material
All cells contain DNA at some point of
their
life
the
RBC's ( red blood cells )lose DNA when leaving
bone for the blood stream
genetic material that carries information
needed to make new cells and
organisms
is passed from parent cells to new cells
controls cell activities
In some cells DNA is enclosed in an
organelle called a nucleus
IV. Two Kinds of Cells
A. All cells have
cell membranes, cytoplasm and
DNA
B. Two Basic Types of Cells
Prokaryotic Cells
prokaryotes
single cell
no nucleus
2 types
Eukaryotic Cells
eukaryotes
V. Prokaryotes: Eubacteria and Archaebacteria
A. Eubacteria ( or just bacteria)
most common
world's smallest cell
doesn't have a nucleus
DNA is in a long chain
No membrane covered organelles
does have ribosomes
( tiny organelles made of protein)
strong web-like outer wall ( cell wall)
protects, give shape, allows nutrients to pass in
and out
live in soil, water and other organisms
B. Archaebacteria
not as common
similar in many ways
single cell
have ribosomes
have cell membranes
has circular DNA
lack memebrane covered
organelles
differences
ribosomes look different
cell wall and membrane are
3 types of archaebacteria
Heat loving
Salt loving
Methane making
Extremeophiles
heat loving, salt loving
live where conditions are
extreme
hot springs, very salty
water
VI. Eukaryotic Cells/ Eukaryotes
A. Eukaryote
an organism with a nucleus and
membrane covered organelles
largest cell ( 10x bigger than
bacteria)
have nucleus with DNA
membrane covered organells
each has a specific job
B. All living things that are not bacteria or
achaebacteria are made of
eukaryotic
cells
C. Types of eukaryotes
animals
plants
fungus
yeast
mushrooms
protists
algae
amoebas
D. Multicellular
"many cells"