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When a plasma membrane is split by freez...

When a plasma membrane is split by freeze-fracture into its outer and inner leaflets, the "bumps' visualized in electron micrographs are replicas of:

A

integral proteins

B

cholesterol molecules

C

phospholipids

D

peripheral proteins

Text Solution

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The correct Answer is:
To answer the question regarding what the "bumps" visualized in electron micrographs are replicas of when a plasma membrane is split by freeze-fracture into its outer and inner leaflets, we can follow these steps: ### Step-by-Step Solution: 1. **Understanding Freeze-Fracture Technique**: - The freeze-fracture technique is a method used to study the structure of biological membranes. It involves freezing the membrane and then fracturing it to separate the outer and inner leaflets. **Hint**: Remember that freeze-fracture allows us to visualize the internal structures of the membrane by splitting it. 2. **Identifying Components of the Plasma Membrane**: - The plasma membrane consists of various components, including phospholipids, integral proteins, peripheral proteins, and cholesterol molecules. Each of these has a different role and location within the membrane. **Hint**: Consider the roles and locations of different membrane components to determine which ones would remain attached after the membrane is fractured. 3. **Analyzing the Role of Integral Proteins**: - Integral proteins span across the membrane and are embedded within the lipid bilayer. When the membrane is split, these proteins remain attached to one of the leaflets, appearing as "bumps" in the electron micrograph. **Hint**: Think about which proteins are likely to remain associated with the membrane after it has been fractured. 4. **Evaluating Other Components**: - Peripheral proteins are located on the outer surface of the membrane and would not create bumps on the fractured surface. Phospholipids, while they form the bilayer, would not create distinct bumps as they are distributed throughout the membrane. Cholesterol molecules are also embedded within the membrane but do not form prominent bumps. **Hint**: Eliminate options that do not remain attached to the membrane after it is fractured. 5. **Conclusion**: - The "bumps" visualized in the electron micrographs after freeze-fracture are replicas of integral proteins, as they are the components that remain attached to one of the leaflets and are visible in the electron micrographs. **Final Answer**: The "bumps" are replicas of **integral proteins**.
To answer the question regarding what the "bumps" visualized in electron micrographs are replicas of when a plasma membrane is split by freeze-fracture into its outer and inner leaflets, we can follow these steps: ### Step-by-Step Solution: 1. **Understanding Freeze-Fracture Technique**: - The freeze-fracture technique is a method used to study the structure of biological membranes. It involves freezing the membrane and then fracturing it to separate the outer and inner leaflets. **Hint**: Remember that freeze-fracture allows us to visualize the internal structures of the membrane by splitting it. ...
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