The Cell Membrane
and
Transport Across the Cell Membrane
Prokaryotes
Eukaryotes
Cell membrane
Ribosomes
Cell wall
Animal Cells
Lysosomes
Plant Cells
Cell membrane
Ribosomes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Vacuoles
Mitochondria
Cytoskeleton
Cell Wall
Chloroplasts
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton
Cell Membrane
protects and supports prokaryotic
and eukaryotic cells and organelles
The cell membrane is a fluid, semi-permeable bilayer that separates the
cell's contents from the environment.
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Michondrion
Cell Membrane
• Fluid at physiological temperatures and allows
cells to change shape due to physical
constraints or changing cellular volumes.
• Regulates movement of molecules from one
side to the other
Phosholipids – form the phospholipid
bilayer of the cell membrane
Phospholipids - form the phospholipid membranes that surround the cell and intracellular
organelles such as the mitochondria.
The phospholipid membrane allows free diffusion of some small molecules such as
oxygen, carbon dioxide, and small hydrocarbons, but not charged ions, polar molecules or
other larger molecules such as glucose, salt .
Semi-permeable – allows some things to pass through and not other things
http://ekgenius.net/Physio/Cell/membrane.html
Max-Planck-Institut für biophysikalische Chemie
Figure 7-15
The Structure of the Cell Membrane
Fluid Mosaic Model
Outside
of cell
Proteins
Carbohydrate
chains
Cell
membrane
Inside
of cell
(cytoplasm)
Protein
channel
Lipid bilayer
Diffusion
Diffusion causes many substances to move across
a cell membrane but does not require energy.
The movement of
water across a semi
permeable membrane.
Osmosis is the
movement of water
(red dots) through a
semipermeable
membrane to a higher
concentration of
solutes (blue dots).
Osmosis does not
require energy.
What is Osmosis?
Osmosis – water moves from a higher concentration to a lower concentration
until equilibrium is reached
Higher Concentration
of Water
Water molecules
Cell
membrane
Lower Concentration
of Water
Sugar molecules
Facilitated Diffusion- Diffusion of larger molecules (glucose, starch, salts) using
protein channels in the cell membrane, does not require energy
Glucose
molecules
High
Concentration
Cell
Membrane
Low
Concentration
Protein
channel
Passive Transport
• When material move from areas of high
concentration to low concentration they don’t
requires energy.
– Examples
• Diffusion
• Facilitate Diffusion
• Osmosis
Particles
Water
Active Transport
• When material move from areas of low
concentration to high concentration they
requires energy.
– Examples
• Endocytosis
• Exocytosis
Exocytosis
Endocytosis
Types of Endocytosis
• Phagocytosis
• Pinocytosis
Pinocytosis
Pinocytosis
Levels of Organization
Levels of Organization
Muscle cell
Smooth muscle tissue
Stomach
Digestive system
Interactive Review
http://www.northland.cc.mn.us/biology/BIOLOGY1111/animations/passive1.swf
http://www.phschool.com/atschool/phbio/active_art/diffusion/index.html
http://www.phschool.com/atschool/phbio/active_art/active_transport/index.html