3.3 Cell Membrane KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.

3.3 Cell Membrane Main component of a membrane is a phospholipid moleculeof the membrane is a phospholipid

3.3 Cell Membrane What happens when they come in contact with water?

3.3 Cell Membrane When mixed into water they rearrange to satisfy both hydrophilic and hydrophobic ends

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. cell membrane

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. – –forms a boundary between inside and outside of the cell cell membrane outside cell inside cell

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane has two major functions. – –forms a boundary between inside and outside of the cell – –controls passage of materials cell membrane outside cell inside cell

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers and other molecules

3.3 Cell Membrane cell membrane Cell membranes are composed of two phospholipid layers and other molecules The cell membrane is made of a phospholipid bilayer.

3.3 Cell Membrane cell membrane Cell membranes are composed of two phospholipid layers and other molecules The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. Cholesterol Carbohydrates Proteins Integral Peripheral

3.3 Cell Membrane cell membrane Cell membranes are composed of two phospholipid layers and other molecules The cell membrane is made of a phospholipid bilayer. There are other molecules embedded in the membrane. The fluid mosaic model describes the membrane. protein cholesterol protein carbohydrate chain protein channel

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

3.3 Cell Membrane Cell membranes are composed of two phospholipid layers. The cell membrane is selectively permeable. Some molecules can cross the membrane while others cannot.

3.3 Cell Membrane What types of things can pass through a phospholipid bilayer? Small uncharged molecules K 2 OFe 2 Water H2OH2O Gases O 2 CO 2 N 2

3.3 Cell Membrane What types of molecules cannot pass through a phospholipid bilayer? Large Particles GlucoseAmino acids TriglyceridesATP Charged Particles Na + K + NO 2 -1 H +

3.3 Cell Membrane Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors.

3.3 Cell Membrane Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. – –intracellular receptor

3.3 Cell Membrane Chemical signals are transmitted across the cell membrane. Receptors bind with ligands and change shape. There are two types of receptors. – –intracellular receptor – –membrane receptor