Cell Biology: Cell Membrane Flashcards

Cell Membrane Overview

• Functions to contain cytoplasm and regulate material transfer in and out of the cell.
• Considered a sophisticated organelle integral to cellular function.

Selective Permeability

• Allows selective entry of specific ions and organic compounds, such as sodium (Na) and water (H2O).
• Ensures that only necessary substances can enter the cytoplasm.

Structure of the Cell Membrane

• Composed of a bilayer of phospholipids.
• The bilayer arrangement is crucial for its functional properties.

Phospholipid Composition

• Made of a hydrophilic phosphate group head and two hydrophobic fatty acid tails.
• This structure contributes to the membrane's selective permeability.

Hydrophilic vs. Hydrophobic

• Hydrophilic substances attract water, whereas hydrophobic substances repel water.
• These properties influence how substances interact with the cell membrane.

Cell Membrane Presence

• Present only in living cells, refuting the idea that they exist in dead cells.

Classification of Proteins

• Proteins can be categorized based on their location (peripheral vs. transmembrane) or their functions (channels, gatekeepers, glycoproteins).

Types of Membrane Proteins

• Peripheral proteins are located on the membrane's exterior, aiding in cell identification.
• Transmembrane proteins span the membrane and function as gatekeepers, forming channels for material transport.

Function of Various Proteins

• Channel proteins facilitate the passage of materials through the membrane.
• Glycoproteins provide cells with a unique identity and assist in immune response.

Glycoproteins in Action

• Determine blood type and play a role in identifying foreign invaders in the body.

Gatekeeper Proteins

• Maintain selective permeability, opening and closing in response to encountered materials.
• Examples include the process of insulin entering cells and neuronal signaling processes.