Question

Which of these statements about the facilitated diffusion of glucose is true? a. There is a net movement from the region of lower to the region of higher concentration. b. Carrier proteins in the cell membrane are required for this transport. c. This transport requires energy obtained from ATP. d. It is an example of cotransport.

Short answer

b. Carrier proteins in the cell membrane are required for this transport.

Step-by-step solution

Review Facilitated Diffusion

Facilitated diffusion is a type of passive transport where molecules such as glucose move across the cell membrane down their concentration gradient, from high to low concentrations. This process does not require energy and utilizes carrier proteins that are specific for the molecules being transported.

Evaluate Each Statement

Now let's evaluate each statement and see which one is true. a. There is a net movement from the region of lower to the region of higher concentration. This statement is incorrect. In facilitated diffusion, the molecules move down their concentration gradient, meaning from a region of higher to a region of lower concentration. b. Carrier proteins in the cell membrane are required for this transport. This statement is correct. Facilitated diffusion relies on carrier proteins in the cell membrane to transport molecules, such as glucose, across the membrane. c. This transport requires energy obtained from ATP. This statement is incorrect. Facilitated diffusion is a passive transport process, meaning it does not require energy in the form of ATP. The transport occurs due to the difference in concentration across the membrane. d. It is an example of cotransport. This statement is incorrect. Cotransport is a form of active transport that involves the movement of two or more different molecules or ions across the membrane using a transport protein. Facilitated diffusion is a passive transport process and does not involve the movement of multiple molecules or ions together. #Conclusion# Based on the evaluation of each statement, the correct answer is: b. Carrier proteins in the cell membrane are required for this transport.

Key concepts

Passive Transport

Passive transport is a fundamental biological process that involves the movement of molecules across cell membranes without the need for energy expenditure. Unlike active transport that requires energy, passive transport utilizes the natural kinetic energy of molecules moving along their concentration gradients. This means that molecules move from an area of higher concentration to an area of lower concentration.
In the context of cells, passive transport is crucial because it allows essential substances like nutrients and gases to enter and exit the cell without the cell expending any of its ATP energy reserves.

• It helps cells maintain equilibrium by balancing concentrations of substances inside and outside the cell.
• It is subdivided into diffusion, osmosis, and facilitated diffusion, each with its specific mechanisms.
• Facilitated diffusion, although passive, requires specialized proteins to assist in moving substances across the membrane safely and efficiently.

This process is essential to the survival of cells as it is energy efficient and helps maintain homeostasis within the bodily environment.

Carrier Proteins

Carrier proteins play a critical role in facilitated diffusion, a type of passive transport. These proteins are embedded in the cell membrane and operate as selective passageways for molecules that cannot easily diffuse through the lipid bilayer due to their size or polarity.
Carrier proteins are specific to the substances they transport. For instance, they might facilitate the diffusion of glucose or ions, each having specific carrier proteins dedicated to their transport.

• They undergo a slight change in shape to transport molecules from one side of the membrane to the other.
• The need for carrier proteins arises because, while small nonpolar molecules can easily diffuse across the membrane, larger or polar molecules like glucose cannot.
• This selectivity ensures that only particular substances are transported, maintaining cellular integrity and function.

By acting as gatekeepers, carrier proteins ensure proper cellular function and contribute to metabolic processes by enabling crucial molecules like glucose to enter cells efficiently.

Glucose Transport

Glucose transport via facilitated diffusion is a great example of passive transport operating through carrier proteins. The process is vital for cells to obtain glucose, an essential fuel for energy production.
Because glucose is a large and polar molecule, it cannot freely diffuse through the cell membrane. To overcome this, cells employ a specific type of carrier protein known as glucose transporters (GLUT).

• These transporters bind to glucose molecules outside the cell, facilitating their movement into the cell where the concentration of glucose is lower.
• Once inside the cell, glucose can be used in cellular respiration to produce ATP, the energy currency of the cell.
• The activity of glucose transporters is regulated based on the cell's energy needs and the availability of glucose in the bloodstream.

This system of glucose transport ensures that cells have a steady supply of glucose for energy production while maintaining precise control over how much glucose enters the cell at any given time, contributing to overall energy homeostasis in the body.