Question

In: Biology

Cells require a constant exchange of solutes (ions and small molecules) with the outside of the cell.

Cells require a constant exchange of solutes (ions and small molecules) with the outside of the cell. Many of these solutes undergo passive transport across the membrane. Passive transport occurs without the input of cellular energy. Some solutes are transported into the cell while others are transported out of the cell.

Part A - Diffusion

All molecules have energy that causes thermal motion. One result of thermal motion is diffusion: the tendency of substances to spread out evenly in the available space. Although the motion of each individual molecule is random, there can be directional motion of an entire population of molecules. Consider a chamber containing two different types of dye molecules, purple and orange. The chamber is divided into two compartments (A and B) by a membrane that is permeable to both types of dye. Initially (left image), the concentration of the orange dye is greater on side \(\mathrm{A},\) and the concentration of the purple dye is greater on side B. With time, the dye molecules diffuse to a final, equilibrium state (right image) where they are evenly distributed throughout the chamber.

Drag the labels onto the table to indicate when each statement is true. Labels can be used once, more than once, or not at all.

Part B - Permeability of the lipid bilayer

Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred to as selective permeability.

Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply.

  • ions
  • oxygen
  • water
  • proteins
  • sucrose
  • carbon dioxide
  • lipids

Part \(\mathrm{C}\) - Facilitated diffusion via channels and carrier proteins

The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in the plasma membrane is called facilitated diffusion.

Sort the phrases into the appropriate bins depending on whether they are true only for channels, true only for carrier proteins, or true for both channels and carriers.

Solutions

Expert Solution

Part A:

Part B:

  • ions
  • oxygen
  • water
  • proteins
  • sucrose
  • carbon dioxide
  • lipids

Part C:

Related Solutions

How do protein pumps move ions and small molecules across a cell membrane?
How do protein pumps move ions and small molecules across a cell membrane?
If a cell has less concentration of solutes inside than outside, it is in a(n) ___________...
If a cell has less concentration of solutes inside than outside, it is in a(n) ___________ environment. Hypertonic Isotonic Hypotonic Mesotonic
Tight junctions: a. allow communication between cells and an exchange of ions b. cause cell membranes...
Tight junctions: a. allow communication between cells and an exchange of ions b. cause cell membranes to tightly fuse together c. extend around the cell like a belt d. connect adjacent cells and their cytoskeleton e. all of the above
In most resting cells, the concentration of sodium ions is higher outside of cells compared with...
In most resting cells, the concentration of sodium ions is higher outside of cells compared with the intracellular fluid. When cells are stimulated, sodium ion channels open, and sodium diffuses from the outside of the cell to the inside of the cell. Sodium ion concentrations in a resting cell are an example of ___________, and sodium ion movement in a stimulated cell is an example of ___________. the energy of motion; stored energy potential energy; kinetic energy kinetic energy; potential...
Which cell-cell connection allows for the formation of a gradient of 2nd messengers, small molecules or...
Which cell-cell connection allows for the formation of a gradient of 2nd messengers, small molecules or ions in the cytosol of neighboring animal cells? a Plasmodesmata b Adherens junction c Gap junction
in autorthythmic cells, influx of these two ions bring the cell threahold? A) sodium B) calcium...
in autorthythmic cells, influx of these two ions bring the cell threahold? A) sodium B) calcium C) chloride D) potassium
18.) Molecules (like adrenaline or epinephrine) that signal from outside the cell use receptors because: a....
18.) Molecules (like adrenaline or epinephrine) that signal from outside the cell use receptors because: a. they are hydrophobic and cannot enter the cell b. they are hydrophilic and cannot enter the cell 19.) Photoautotrophs are essential to life on earth because: a. they make their own food b. They provide energy for other organisms c. they eat harmful insects d. A and B e. B and C. 20.) Signaling through receptors allow cells to respond to small differences in...
Animal cells generally have a higher concentration of Na+ outside of the cell than inside the...
Animal cells generally have a higher concentration of Na+ outside of the cell than inside the cell and a membrane potential around -70 mV. When an Na+ moves into an animal cell, how does that movement impact the membrane potential? How does that movement impact the Na+ concentration gradient? Explain what an equilibrium potential for an ion is, what the resting membrane potential is, and how they are different.
1. Specific extracellular signal molecules require a cell surface receptor. What about the chemistry of these...
1. Specific extracellular signal molecules require a cell surface receptor. What about the chemistry of these signals prevents them from diffusing across the cell membrane? 2. What is the difference between endocrine signaling, paracrine signaling and autocrine signaling? 3. Why do cellular signal molecules bing to a receptor using noncovalent forces rather than a covalent bond? 4. What is the different between kinases and phosphates? How do they impact activity of the target protein. Please give an example that involves...
1. Which of the following statements is NOT true about cell size? Larger cells require more...
1. Which of the following statements is NOT true about cell size? Larger cells require more materials to survive. Material needs are tied to Volume. Maximum cell size is limited by the surface area to volume ratio When cell volume is doubled, the surface area is also doubled. As a cell increases in size, the volume increases faster than its surface area The amount of surface area of a cell determines how much material can be absorbed through the membrane...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT