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 Membrane Transmembrane Protein  Goes through the cell membrane Extrinsic Protein Found on outside of cell membrane Intrinsic Protein – Found on inside 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 Phospholipids Protein

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