17. Transmembrane proteins are involved in the transport of sugars across the plasma membrane.Glucose can be moved into cells by facilitated diffusion using proteins called GLUT proteins. Theseproteins expose a single binding site on one side of the membrane. Glucose binds to this site and causesa change in the shape of the protein. This change moves the glucose across the membrane and releasesit on the other side.i. Explain why facilitated diffusion via GLUT proteins requires no metabolic energy.

Facilitated diffusion via GLUT proteins requires no metabolic energy because it is a passive transport process. In passive transport, substances move from an area of higher concentration to an area of lower concentration, a process known as moving down the concentration gradient. This is essentially the substance moving from where it is in excess to where it is less, until equilibrium is reached.

In the case of glucose transport via GLUT proteins, glucose outside the cell (where it is in higher concentration) binds to the GLUT protein. This binding causes a conformational change in the GLUT protein that allows glucose to be transported across the membrane and released inside the cell (where glucose concentration is lower).

This process does not require energy because it is driven by the concentration gradient, not against it. If glucose were to be transported from an area of low concentration to an area of high concentration (against the gradient), that would require energy in a process known as active transport. But in the case of GLUT proteins, the process is passive (down the gradient) and thus energy-free.

Facilitated diffusion via GLUT proteins requires no metabolic energy because it is a passive transport process. In passive transport, substances move from an area of higher concentration to an area of lower concentration, a process known as moving down the concentration gradient. This is essentially the substance moving from where it is in excess to where it is less, until equilibrium is reached.

In the case of glucose transport via GLUT proteins, glucose outside the cell (where it is in higher concentration) binds to the GLUT protein. This binding causes a conformational change in the GLUT protein that allows glucose to be transported across the membrane and released inside the cell (where glucose concentration is lower).

This process does not require energy because it is driven by the concentration gradient, not against it. If glucose were to be transported from an area of low concentration to an area of high concentration (against the gradient), that would require energy in a process known as active transport. But in the case of GLUT proteins, the process is passive (down the gradient) and thus energy-free.