The Cell Membrane and

Transport Across the Cell Membrane

Prokaryotes Eukaryotes

Cell membraneRibosomesCell wall

NucleusEndoplasmic reticulumGolgi apparatusLysosomesVacuolesMitochondriaCytoskeleton

Animal Cells Plant Cells

Lysosomes

Cell membraneRibosomesNucleusEndoplasmic reticulumGolgi apparatusVacuolesMitochondriaCytoskeleton

Cell WallChloroplasts

Cell Membrane protects and supports prokaryotic and

eukaryotic cells and organelles

Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Michondrion

The cell membrane is a fluid, semi-permeable bilayer that separates the cell's contents from the environment.

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

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Figure 7-15 The Structure of the Cell Membrane Fluid Mosaic Model

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?

Cellmembrane

Higher Concentrationof Water

Lower Concentrationof Water

Water molecules

Sugar molecules

Osmosis – water moves from a higher concentration to a lower concentration until equilibrium is reached

HighConcentration

LowConcentration

CellMembrane

Glucosemolecules

Proteinchannel

Facilitated Diffusion- Diffusion of larger molecules (glucose, starch, salts) using protein channels in the cell membrane, does not require energy

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

Muscle cell Smooth muscle tissue Stomach Digestive system

Levels of Organization

http://www.northland.cc.mn.us/biology/BIOLOGY1111/animations/passive1.swf

Interactive Review

http://www.phschool.com/atschool/phbio/active_art/diffusion/index.html

http://www.phschool.com/atschool/phbio/active_art/active_transport/index.html