C7- A View of the Cell
A View of the Cell
 7-1
Discovery of Cells
 7-2 Plasma Membrane
 7-3
Discovery of Cells

Anton van
Leeuwenhoek used
the first microscope
early in the 1600s.
 It revealed the world
of microorganisms
and cells which are
the basic unit of an
organism.
Discovery of Cells

Robert Hooke coined
the term cell after
observing cork under
a microscope.
Hooke’s illustration of cork
Discovery of Cells

1838 Matthias
Schleiden observed
plant cells.
 Theodor Schwann
studied animal cells.
 Ideas were
summarized in the
Cell Theory.
Cell Theory
 1.
All organisms are made of one or more
cells.
 2. The cell is the basic unit of structure
and organization in organisms.
 3. All cells come from preexisting cells.
Electron Microscopes

Light Microscopes
1500X
 Dev new EM in 1930s
& 40s
 Uses beam of
electrons to multiply
image 500,000X
 Lets us see internal
cell structure
Scanning vs. Transmission EM

Scan surface of cell
for 3D image
 Study internal
structure of cell
Two Basic Cell Types

All cells contain
specialized structures
called organelles.
 Eukaryotes have
membrane-bound
organelles
 Prokaryotes do not
 Some eukaryotes are
unicellular like
amoebas.
Two Basic Cell Types

Robert Brown
observed eukaryotes
had a prominent
structure.
 Rudolf Virchow said it
was responsible for
cell division.
 Eventually the
structure was called
the nucleus or cell’s
control center.
7.2 Plasma Membrane

Responsible for controlling what goes in and out
of the cell.
Plasma Membrane

Maintains
homeostasis by
selective
permeability keeping
some things in and
keeping others out
Plasma Membrane Structure

Phospholipid Bilayer
 Glycerol backbone, 2
fatty acids & a
phosphate group
make a phospholipid.
 Water is attracted to
the head but not to
the lipid fatty acids.
Plasma Membrane Structure

Fluid Mosaic Model
because
phospholipids ripple
like water with the
currents.
 Protein molecules
float like boats on the
surface in a mosaic
pattern.
 Flexible
Other components

Cholesterol
stabilizes the
phospholipids by
keeping the the tails
from sticking together
 Transport proteins
span the membrane
to move needed
substances in and
wastes out of the cell.
7.3 Eukaryotic Cell Structure

Each component has
a specific function.
 They work together to
help the cell survive.
 Cell wall fairly rigid
part of plant cells,
bacteria & protists
made of cellulose.
Eukaryotic Cell Structure





Nucleus
Cell Control
Contains directions
for making proteins in
chromatin.
Strands of genetic
material, DNA
Chromatin condenses
to chromosomes
before cell division
Eukaryotic Cell Structure

Nucleolus
 Makes ribosomes
 Ribosomes are
production site of
proteins made by
direction of DNA
 They’re made of RNA
and must travel to the
cytoplasm to build
proteins.

The nucleolus makes
ribosomes which are
the site of protein
synthesis.
 Ribosomes must
travel out of the
nucleus to the
Cytoplasm where
they build the proteins
according to DNAs
direction.
Eukaryotic Cell Structure

Cytoplasm
 Clear, gelatinous fluid
inside a cell
 Ribosomes and RNA
pass through nuclear
pores in the nuclear
envelope to enter the
cytoplasm
Eukaryotic Cell Structure

Assembly, transport &
storage
 Endoplasmic
reticulum site of
cellular chemical
reactions
 Highly folded
membrane which
ribosomes attach to
(Rough ER) do
protein synthesis
Eukaryotic Cell Structure

Each protein has a
specific function.
 Smooth ER has no
ribosomes but makes
and stores lipids.
 After proteins are
made they’re sent to
the Golgi Apparatus
Eukaryotic Cell Structure

Golgi Apparatus
 Modifies proteins &
sorts them into
packages (vesicles)
for transport to their
destination
Eukaryotic Cell Structure

Vacuoles membrane
bound compartment
for temporary storage
 Stores food, enzymes
& other needed
materials.
 Animal cells may also
have vacuoles usually
smaller.
Eukaryotic Cell Structure

Lysosomes contain
digestive enzymes.
 Used to digest worn
out organelles, food
particles or engulfed
viruses or bacteria.
 The membrane
prevents enzymes
from destroying the
cell.
Eukaryotic Cell Structure

Energy Transformers
 Chloroplasts capture
light energy & convert
it to chemical energy.
Eukaryotic Cell Structure