According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly a. spread in a continuous layer over the inner and outer surfaces of the membrane. b. confined to the hydrophobic interior of the membrane. c. embedded in a lipid bilayer. d. randomly oriented in the membrane, with no fixed inside-outside polarity.

Verified step by step guidance

1. Understand the fluid mosaic model: The fluid mosaic model describes the structure of cell membranes, where the membrane is a fluid combination of lipids and proteins.
2. Identify the role of proteins in the membrane: In this model, proteins are not just on the surface; they are integrated into the lipid bilayer.
3. Analyze the options: Option (a) suggests proteins form a continuous layer, which is incorrect as proteins are interspersed within the lipid bilayer. Option (b) is incorrect as proteins are not confined only to the hydrophobic core; they also span through to the hydrophilic surfaces. Option (d) is incorrect as proteins generally have specific orientations.
4. Recall the lipid bilayer structure: The lipid bilayer has a hydrophobic interior and hydrophilic exterior, and proteins are embedded within this bilayer to perform various functions.
5. Choose the correct answer: Based on the fluid mosaic model and the structure of the lipid bilayer, the correct answer is (c) embedded in a lipid bilayer.

Key Concepts

Fluid Mosaic Model

The fluid mosaic model describes the structure of cell membranes as a dynamic and flexible arrangement of various components, including lipids and proteins. In this model, the lipid bilayer acts as a fluid medium in which proteins are embedded, allowing for movement and interaction. This model emphasizes that membranes are not static but rather exhibit fluidity, enabling cellular processes such as signaling and transport.

Lipid Bilayer

The lipid bilayer is a fundamental structure of cell membranes, composed of two layers of phospholipids. Each phospholipid molecule has a hydrophilic (water-attracting) 'head' and two hydrophobic (water-repelling) 'tails.' This arrangement creates a semi-permeable barrier that separates the internal environment of the cell from the external surroundings, allowing selective passage of substances and maintaining homeostasis.

Membrane Proteins

Membrane proteins are integral or peripheral proteins that perform various functions within the cell membrane. They can be embedded within the lipid bilayer or attached to its surface, playing roles in transport, signaling, and structural support. The orientation and distribution of these proteins are crucial for their function, as they interact with both the extracellular environment and the cytoplasm, facilitating communication and material exchange.