Question

other important parts of the membrane
although the bilayer is made of phospholipids, it also includes:

1. proteins – help with ____________ and ____________.
2. carbohydrates – help with ______________ and identifying the cell.
3. cholesterol – helps the membrane stay ______________.

key term review
fill in the definitions:

• phospholipid: a molecule with a water-loving ____ and two water-fearing ____.
• bilayer: two _______ of phospholipids.
• hydrophilic: means \______________.\
• hydrophobic: means \______________.\
• selective permeability: the membrane lets some things ____ and keeps other things ____.

Explanation:

• Proteins in the membrane are involved in transport (moving substances across the membrane) and communication (signaling between cells).
• Carbohydrates on the membrane help in cell - cell recognition.
• Cholesterol maintains the fluidity of the membrane.
• A phospholipid has a hydrophilic (water - loving) head and hydrophobic (water - fearing) tails.
• A bilayer is composed of two layers of phospholipids.
• Hydrophilic means "water - loving".
• Hydrophobic means "water - fearing".
• Selective permeability implies that the membrane allows some substances to pass through (enter) and keeps others out.

Answer:

1. Proteins – help with transport and communication.
2. Carbohydrates – help with cell - cell recognition and identifying the cell.
3. Cholesterol – helps the membrane stay fluid.

• Phospholipid: A molecule with a water - loving head and two water - fearing tails.
• Bilayer: Two layers of phospholipids.
• Hydrophilic: Means "water - loving".
• Hydrophobic: Means "water - fearing".
• Selective permeability: The membrane lets some things in and keeps other things out.