Cell Membrane Structure

The Cell Membrane

• It is important to know the composition of the cell membrane because each part is responsible for bringing a type of nutrient into the cell.

Components of the cell membrane

• Phospholipids (Yes these are a type of lipid) • Proteins• Carbohydrates

Phospholipids

• Make up a majority of the cell membrane• Small molecules (such as water and oxygen)

can pass freely between phospholipids• Phospholipid structure:

Hydrophilic head (loves water) Faces towards water

Hydrophobic tail (Water fearing) Faces away from water

Phospholipids

• Exist in a bilayer – “2 layers”

• Heads face out of the cell and inside the cell• Tails cluster in the middle (see pictures)

Proteins

• Some are embedded on the inside of the cell membrane – Intrinsic proteins

• Some are embedded on the outside of the cell membrane – Extrinsic proteins

• Some pass through the cell membrane – Transmembrane Proteins

• All are involved in moving things into or out of the cell membrane

Proteins in the Cell MembraneTransmembrane Protein Goes through the cell membrane

Intrinsic Protein – Found on inside of cell membrane

Extrinsic ProteinFound on outside of cell membrane

Carbohydrates

• Made of Glycogen (Type of polysaccharide)• 2 types:– Glycoproteins

• Attached to proteins on the cell membrane• Used in cell to cell recognition

– Glycolipids• Attached to phospholipids on the cell membrane• Used to recognize foreign substances in the environment

• Both are found on outside of cell membrane

Carbohydrates

Protein

Phospholipids

Cell Membrane Structure Review

• Made mainly of Phospholipids– Exist in a bilayer– Hydrophilic head faces outside and inside of cell– Hydrophobic tail faces the middle of the membrane

• Proteins are embedded on the surface and through the membrane– Intrinsic – Inside of cell– Extrinsic – Outside of cell– Transmembrane – Extend through cell

Cell Membrane Structure Review

• Carbohydrates extend from the surface of the membrane to sense the environment– Glycolipids – Attach to phospholipids– Glycoproteins – Attach to proteins