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Chapter 7
Section 1
Section 1
• Before microscope
were invented, people
believed that diseases
were caused by curses
and supernatural
spirits.
• Microscopes enable
scientists to view and
study cells, the basic
unit of life.
• Compound light microscope:
uses a series of lenses to
magnify objects in steps.
• Electron microscope: uses a
beam of electrons instead of
light to magnify structures up
to 500,000 times their actual
size.
–Transmission electron
microscope: allows scientists
to study the structures
contained within a cell.
–Scanning electron
microscope: helps find the
three-dimensional shape of
the cell by scanning the
surface of the cell.
The Cell Theory
1. All organisms are
composed of one
or more cells.
2. The cell is the
basic unit of
living things.
3. All cells come
from preexisting
cells.
Theodor Schwann
made the
fundamental ideas of
the cell theory.
Two basic cell types
1. Prokaryotes: Cells that do not
contain any membrane bound
organelles.
2. Eukaryotes: Contains a true
nucleus and membrane bound
organelles. Can be one cell or
multicellular.
Prokaryotes
Eukaryotes
The organelle
that manages
or controls
cellular
functions is
called the
nucleus.
Section 2
• The plasma membrane allows a
steady supply of nutrients to
come into the cell no matter
what the external conditions
are.
• Waste and other products also
leave the cell through the PM
• Homeostasis
How does it maintain
homeostasis???
Through selective
permeability. This is a process
in which a membrane allows
some molecules to pass
through while keeping others
out.
Water can pass in and out –
sodium and ions are regulated
Structures of the Plasma
Membrane
Structure of the Plasma
Membrane
• Lipids are large biomolecules
that are composed of glycerol
and 3 fatty acids.
•Phospholipids are liquid with an
attached phosphate group.
The phospholipid bilayer
• The phosphate
group is critical for
the formation and
function of the
plasma membrane.
• The fatty acid tail is
non-polar and the
phosphate head is
polar
• Water is a key component of
living organisms – both inside
and out.
• The polar phosphate group
allows the CM to interact with
the water because water is also
polar.
• The fatty acid tail avoids water.
• The 2 layers make a sandwich
and create a barrier.
Model of the plasma membrane is
called the Fluid Mosaic Model
• The
F.M. Model is a structure
model of the plasma membrane
where molecules are free to move
sideways within a lipid bilayer.
•Transport proteins move needed
substances or waste material
through the plasma membrane.
•See page 178
Components of the plasma
membrane.
• Cholesterol – stabilizes the
phospholipids by preventing the
fatty acid tails from sticking
• Proteins are in the lipid membrane
• Transport proteins – move needed
substances through the plasma
membrane
Section 3 – Parts of the Cell
Plant
Animal
Cell Wall
• Most
commonly
found in plant
cells &
bacteria
• Supports &
protects cells
Cell Membrane
• Outer
membrane of
cell that
controls
movement in
and out of the
cell
• Double layer
Cytoplasm
• Gel-like mixture
• Surrounded by cell
membrane
• Contains hereditary
material
Chloroplast
• Usually found
in plant cells
• Contains green
chlorophyll
• Where
photosynthesis
takes place
Ribosomes
• Each cell
contains
thousands
• Make proteins
• Found on
ribosomes &
floating
throughout the
cell
Mitochondria
• Produces energy
through chemical
reactions – breaking
down fats &
carbohydrates
• Controls level of
water and other
materials in cell
• Recycles and
decomposes proteins,
fats, and
carbohydrates
Endoplasmic Reticulum
• Moves materials
around in cell
• Smooth type:
lacks ribosomes
• Rough type
(pictured):
ribosomes
embedded in
surface
Golgi Bodies
• Protein
'packaging plant'
• Move materials
within the cell
• Move materials
out of the cell
Vacuoles
• Membranebound sacs for
storage,
digestion, and
waste removal
• Help plants
maintain shape
Lysosome
• Contains digestive
proteins
• Transports
undigested material
to cell membrane
for removal
• Cell breaks down if
lysosome explodes
Nucleus
• Directs cell activities
• Separated from cytoplasm
by nuclear membrane
• Contains genetic material DNA
Parts cont.
• Plasma membrane- maintains
homeostasis.
• Chromatin- strands of DNA that direct
the making of proteins.
• Chloroplast- produces food.
• Cytoskeleton- provides internal
structure.
-Microtubules- thin, hollow cylinders
made of protein.
-Microfilaments- smaller, solid
protein fibers.
• Plastids- storage.
• Cilia- short, numerous
projections, look like hair that
aid in locomotion.
• Flagella- longer projections
that move with a whip-like
motion.