Question

cell membrane
the cell membrane is described as a
what else makes up part of the membrane besides phospholipids?
list a few of the roles of proteins in the cell membrane:
what are the types of cell transport?
1.
2.
3.
4.

Explanation:

• The cell membrane is described as a fluid mosaic model. This model reflects the dynamic nature of the membrane, with its components (like phospholipids, proteins, and cholesterol) able to move laterally.
• Besides phospholipids, the membrane contains proteins (integral and peripheral) and cholesterol (in animal cells). Proteins have various roles:
• Transport: Channel and carrier proteins help move substances across the membrane.
• Enzymatic activity: Some proteins act as enzymes, catalyzing reactions at the membrane.
• Signal - transduction: Receptor proteins bind to signaling molecules and initiate a cellular response.
• Cell - cell recognition: Glycoproteins are involved in identifying cells.
• The types of cell transport are:
• Simple diffusion: Movement of small, non - polar molecules (e.g., \(O_2\), \(CO_2\)) from high to low concentration across the membrane.
• Facilitated diffusion: Transport of polar or charged molecules (e.g., glucose, ions) with the help of transport proteins (channel or carrier proteins) down their concentration gradient.
• Active transport: Requires energy (usually ATP) to move molecules against their concentration gradient (e.g., sodium - potassium pump).
• Bulk transport: Includes endocytosis (phagocytosis, pinocytosis) and exocytosis. Endocytosis is the uptake of large particles or fluids by the cell, and exocytosis is the release of substances from the cell.

Answer:

• The cell membrane is described as a fluid mosaic model.
• Besides phospholipids, proteins and cholesterol (in animal cells) make up the membrane.
• Roles of proteins: transport, enzymatic activity, signal - transduction, cell - cell recognition.
• Types of cell transport:

1. Simple diffusion
2. Facilitated diffusion
3. Active transport
4. Bulk transport