Why does water appear to bulge from the sides of a glass?
Adhesion is responsible for a meniscus and this has to do in part with water’s fairly high surface tension. And since water molecules like to stick together, when the molecules touching the glass cling to it, other water molecules cling to the molecules touching the glass, forming the meniscus.
How does water help cells keep an even temperature?
The hydrogen bonds between water molecules give water the ability to hold heat better than many other substances. As the temperature rises, the hydrogen bonds between water continually break and reform, allowing for the overall temperature to remain stable, although increased energy is added to the system.
How does that change the relationship that phospholipids have to water?
A single phospholipid molecule has a phosphate group on one end, called the “head,” and two side-by-side chains of fatty acids that make up the lipid “tails. ” The phosphate group is negatively charged, making the head polar and hydrophilic, or “water loving.” The phosphate heads are thus attracted to the water …
What is the hydrophobic part of a phospholipid?
The hydrophobic, or “water-fearing,” part of a phospholipid consists of its long, nonpolar fatty acid tails. The fatty acid tails can easily interact with other nonpolar molecules, but they interact poorly with water.
What makes the phospholipid bilayer semipermeable?
The polar heads point both outward toward the environment of the cell and inward toward the cytosol. This makes the phospholipid bilayer an excellent semipermeable membrane that allows cells to keep their contents separated from the environment and other cells.
What makes the membrane semipermeable?
The membrane is selectively permeable because substances do not cross it indiscriminately. Some molecules, such as hydrocarbons and oxygen can cross the membrane. Many large molecules (such as glucose and other sugars) cannot. Water can pass through between the lipids.
Why is it important for a cell membrane to be semi permeable?
Cell membranes are semipermeable, which means molecules can move through them. This is pretty important for cells to survive. Osmosis is where solvent molecules (usually water) move from one side of a cell membrane to the other. This happens because the concentration of a solute is higher on one side.
What determines what can pass through the membrane and which direction it will move?
Two factors determine whether a molecule will cross a membrane: (1) the permeability of the molecule in a lipid bilayer and (2) the availability of an energy source.
How are large molecules moved out of the cell?
Exocytosis is the process by which cells move materials from within the cell into the extracellular fluid. Exocytosis occurs when a vesicle fuses with the plasma membrane, allowing its contents to be released outside the cell. They are delivered to other cells following their release from the cell through exocytosis
What uses energy to take particles into a cell?
Endocytosis methods require the direct use of ATP to fuel the transport of large particles such as macromolecules; parts of cells or whole cells can be engulfed by other cells in a process called phagocytosis.
What type of transport requires energy?