34- Below is represented the membrane of a red blood cell. G stand for glucose,
ID: 201790 • Letter: 3
Question
34- Below is represented the membrane of a red blood cell. G stand for glucose, and the membrane potential is negative (inside negatively charged). For each solute, assume that the number of symbols represents its relative concentration. Na Na Na* Cl Cl Na* K CI Outside Cell Membrane - Na* ide K+K a. Indicate which of the solute(s) can enter the cell without the need for a membrane b. Indicate which of the solute(s) can readily enter the cell by simple diffusion. c. Indicate which of the solute(s) can readily enter the cell by facilitated diffusion. d. Indicate the solute(s) for which the movement across the membrane will not be influenced by the membrane potential. Indicate which of the solute(s) can readily enter the cell by channel proteins mediated facilitated diffusion. Indicate which of the solute(s) can only enter the cell by carrier proteins mediated facilitated diffusion. e. f. g. Indicate which of the solute(s) can only enter the cell by active transport. h. Indicate the solute(s) for which the movement across the membrane will be additively influenced by the membrane potential and the concentration gradient. Indicate the direction of net movement. Indicate the solute(s) for which the movement across the membrane will be eppositely influenced by the membrane potential and the concentration gradient. Explain how Indicate the solute for which the movement into the cell will have the most negative free energy change. i. j.Explanation / Answer
34a. Oxygen can enter the cell without the membrane as it can be transported by passive diffusion. It moves from a region of high concentration to low concentration in a cell. Oxygen molecule has no charge. Hence, it does not require interaction with hydrophobic core of the membrane for transport.
Option is oxygen or O2.
b. Oxygen enters through the cell membrane by simple diffusion. Simple diffusion is transport from high concentration to low concentration with no input of energy. Oxygen molecules can move through by random motion.
Option is O2 or oxygen.
c. Facilitated diffusion is passive transport of molecules across a membrane through specific transmembrane proteins. Uptake of glucose by the cell is by facilitated diffusion. The transported molecule does not diffuse in the membrane. Glucose transporter is a 12 -helical transmembrane segments containing carrier protein. Facilitated diffusion of glucose occurs in RBCs where high glucose concentration occurs outside the cell and low glucose concentration inside the cell. Sodium and chloride also move from high to low concentration by facilitated diffusion.
Right option is G or glucose, sodium (Na+) and chloride (Cl-)
d. Transport of uncharged molecules like glucose and oxygen will not be affected by membrane potential. Membrane potential is the difference in concentration of charged ions across a membrane that gives rise to a voltage gradient. Molecules transported by passive transport are not affected by membrane potential.
Right option is glucose (G) and oxygen (O2).
e. Channel proteins form pores through the membrane and allow small molecules to pass through the membrane. Transport of Na+ and chloride will occurs through ion channels. As sodium and chloride concentration is higher on the outside than inside of the cells, these ions can be transported by facilitated diffusion through ion channels.
Right option is Sodium and Chloride.
f. Facilitated diffusion requires specific carrier proteins. These protein bind to the molecules on the extracellular membrane. This induces a conformational change in the carrier protein, so that the carrier protein now faces the inside of the cell. The carrier protein transports the molecules through its pore and releases the molecule to the inside.
Right option is glucose (G).
As per Chegg’s rules, only subparts a-d are mandatory to be answered.
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