3.3 Cell Membrane TEKS 3E, 4B, 9A The student is expected to: 3E evaluate models according to their...

3.3 Cell Membrane TEKS 3E, 4B, 9A

The student is expected to:

3E evaluate modelsaccording to their limitations inrepresenting biological objects orevents; 4B investigate and explaincellular processes, includinghomeostasis, energy conversions,transport of molecules, andsynthesis of new molecules;

3.3 Cell Membrane TEKS 3E, 4B, 9A

(Continued)

9Acompare the structures and functions ofdifferent types of biomolecules,including carbohydrates, lipids, proteins,and nucleic acids

3.3 Cell Membrane TEKS 3E, 4B, 9A

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

3.3 Cell Membrane TEKS 3E, 4B, 9A

Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane TEKS 3E, 4B, 9A

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

cell membrane

3.3 Cell Membrane TEKS 3E, 4B, 9A

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 TEKS 3E, 4B, 9A

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 TEKS 3E, 4B, 9A

Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane TEKS 3E, 4B, 9A

cell membrane

Cell membranes are composed of two phospholipid layers.• The cell membrane is made of a phospholipid bilayer.

3.3 Cell Membrane TEKS 3E, 4B, 9A

cell membrane

Cell membranes are composed of two phospholipid layers.• The cell membrane is made of a phospholipid bilayer.• There are other molecules embedded in the membrane.

protein

cholesterol

proteincarbohydratechain

protein channel

3.3 Cell Membrane TEKS 3E, 4B, 9A

cell membrane

Cell membranes are composed of two phospholipid layers.• 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

proteincarbohydratechain

protein channel

3.3 Cell Membrane TEKS 3E, 4B, 9A

Cell membranes are composed of two phospholipid layers.

3.3 Cell Membrane TEKS 3E, 4B, 9A

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 TEKS 3E, 4B, 9A

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 TEKS 3E, 4B, 9A

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 TEKS 3E, 4B, 9A

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 TEKS 3E, 4B, 9A

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