Cell Biology: What Makes Molecules Hydrophobic & Hydrophilic?

[uio]

Hi

I'm currently studying cell biology, and I'm reading about the hydrophobic parts of the plasma membrane of the animal cell. But I'm wondering, what exactly makes a molecule hydrophilic or hydrophobic? What is the chemistry behind it, and how can I tell which molecules are which? I know that lipids and certain proteins are hydrophobic, but I can't understand why.

Thanks.

 

[Gokul43201]

When a molecule (or a part of a long molecule) is polar (i.e., it has a significant dipole moment), it can attract a water molecule through a dipole-dipole interaction. That is usually what makes it hydrophilic.

 

[quicknote]

I can provide some insight into the chemistry behind hydrophobic and hydrophilic molecules. The terms hydrophobic and hydrophilic refer to a molecule's ability to interact with water. Hydrophobic molecules are nonpolar, meaning they have a relatively equal distribution of electrons and do not have a positive or negative charge. These molecules are typically made up of mainly carbon and hydrogen atoms, and they do not have the ability to form hydrogen bonds with water molecules. This results in a repulsion between the hydrophobic molecule and water, causing them to clump together and avoid contact with water.

On the other hand, hydrophilic molecules are polar, meaning they have an uneven distribution of electrons and have a positive or negative charge. These molecules are typically made up of elements such as oxygen, nitrogen, and phosphorus, which have a higher electronegativity and can form hydrogen bonds with water molecules. This makes them attracted to water and able to dissolve in it.

So, the chemistry behind hydrophobic and hydrophilic molecules is based on the polarity of the molecule and its ability to interact with water. This can be determined by looking at the molecular structure and the types of atoms present in the molecule.

In terms of the plasma membrane of an animal cell, the hydrophobic molecules, such as lipids and certain proteins, make up the interior of the membrane, while hydrophilic molecules, such as phospholipids and glycoproteins, make up the exterior. This helps to maintain the integrity of the membrane and regulate the movement of substances in and out of the cell.

I hope this helps to clarify the chemistry behind hydrophobic and hydrophilic molecules. Keep up the curiosity and continue exploring the fascinating world of cell biology.