Question

A certain membrane protein allows phosphate groups to enter a eukaryotic cell.

(a) Would you expect the protein to function more like KcsA or more like GLUTI?

(b) Phosphate ions enter the cell along with ions. Describe this transport system using the terms introduced in Fig. 10-15.

(c) The eukaryotic intracellular pH is typically slightly lower than the extracellular pH. Does this suggest that the phosphate transporter carries out secondary active transport?

Short answer

In the solution (a), the phosphate ions cannot stop the smaller ions from moving across the membrane.

In the solution (b), the phosphate transporter system is a symport system because it accepts the phosphate groups.

In the solution (c), the phosphate transport is influenced by pH gradient.

Step-by-step solution

Membrane proteins

Membrane proteins are proteins that interact with the biological membrane and ions and are found at the cell membrane. There are two types of membrane proteins: transporter proteins and membrane receptor proteins. The proteins that transport chemicals and ions across the membrane are known as transporter proteins.

In the solution (a), Phosphate transporter membrane protein functions

Phosphate transporter is a membrane protein that lets phosphate groups into the cell. The integral membrane protein KcsA has 158 residues.GLUT1 is a type of passive-mediated transporter that allows molecules to flow across the cell membrane depending on their concentration on both sides. Because a channel big enough to collectphosphate ions exists, the phosphate transporter is more likely to act like a GLUT1 transport protein. Phosphate ions can't stop smaller ions from moving across the membrane.

In the solution (b), Transport system of phosphate ions

The phosphate transporter is a passive-mediated transporter that allows molecules to cross the cell membrane depending on their concentration on both sides. Two molecules can be transported in the same direction using a symport. A phosphate transporter is a symport system because it accepts phosphate groups together with$H^{+}$ions

In the solution (c), Variation of pH in both sides

The internal pH of eukaryotic cells is lower than the external pH, indicating that there are more${\text{H}}^{\text{+}}$ ions inside than outside the cell. The transmembrane transportation of substances is promoted inpassive-mediated transportersdepending on the concentration on both sides of the cell. Because phosphate transport necessitates a higher extracellular ${\text{H}}^{\text{+}}$concentration.