Glucose is needed by all cells in order to do cellular respiration. How does glucose, a large molecule, enter cells without using cell energy?
a
osmosis moving against the concentration gradient
b
via channel proteins using facilitated diffusion
c
using proteins pumps and ATP
d
by employing active transport
d
by employing active transport
The correct answer is b) via channel proteins using facilitated diffusion. Glucose, being a large molecule, cannot passively diffuse across the cell membrane on its own. Instead, it relies on specialized channel proteins called glucose transporters to facilitate its movement across the membrane. These transporters create a channel or tunnel through which glucose can pass, allowing it to move from an area of higher concentration (outside the cell) to an area of lower concentration (inside the cell) without the need for cellular energy. This process is known as facilitated diffusion.
The correct answer is b) via channel proteins using facilitated diffusion.
To understand how glucose, a large molecule, enters cells without using cell energy, let's break down the different options:
a) Osmosis moving against the concentration gradient: Osmosis is the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration. Glucose does not move via osmosis, as it is a large molecule and does not follow the same rules as water.
b) Via channel proteins using facilitated diffusion: Facilitated diffusion is the passive movement of molecules across a membrane with the help of specific proteins called channel proteins. These channel proteins act as channels or tunnels in the cell membrane, allowing specific molecules or ions to pass through. Glucose enters the cells through channel proteins that are selective for glucose molecules, allowing them to move down their concentration gradient without the need for cellular energy.
c) Using protein pumps and ATP: Protein pumps are a type of active transport mechanism that actively moves molecules or ions across a membrane, against their concentration gradient. This process requires the use of ATP (adenosine triphosphate), which is the energy currency of cells. While ATP is involved in various cellular processes, such as active transport, glucose does not enter cells through protein pumps.
d) Employing active transport: Active transport is a cellular process that moves molecules or ions against their concentration gradient, from an area of lower concentration to an area of higher concentration. This process requires the input of cellular energy in the form of ATP. While active transport is crucial for many cellular functions, such as maintaining ion gradients, glucose does not enter cells through active transport.
In summary, glucose enters cells without the use of cell energy by moving through channel proteins via facilitated diffusion. These channel proteins facilitate the transport of glucose molecules across the cell membrane, allowing them to enter the cells effortlessly.