hydrophobic

Examples of hydrophobic in the following topics:

• Water’s Solvent Properties

  • Oils, fats, and certain organic solvents do not dissolve in water because they are hydrophobic.
  • Water is a poor solvent, however, for hydrophobic molecules such as lipids.
  • Nonpolar molecules experience hydrophobic interactions in water: the water changes its hydrogen bonding patterns around the hydrophobic molecules to produce a cage-like structure called a clathrate.
  • Thermodynamically, such a large decrease in entropy is not spontaneous, and the hydrophobic molecule will not dissolve.

• Fluid Mosaic Model

  • Hydrophobic, or water-hating molecules, tend to be non-polar.
  • When placed in water , hydrophobic molecules tend to form a ball or cluster.
  • In contrast, the middle of the cell membrane is hydrophobic and will not interact with water.
  • This type of protein has a hydrophilic region or regions, and one or several mildly hydrophobic regions.
  • This phospholipid molecule is composed of a hydrophilic head and two hydrophobic tails.

• Signaling Molecules

  • Small hydrophobic ligands can directly diffuse through the plasma membrane and interact with internal receptors.
  • Other hydrophobic hormones include thyroid hormones and vitamin D.
  • In order to be soluble in blood, hydrophobic ligands must bind to carrier proteins while they are being transported through the bloodstream.
  • Because these molecules are small and hydrophobic, they can diffuse directly across the plasma membrane into the cell, where they interact with internal receptors.
  • Compare and contrast the different types of signaling molecules:  hydrophobic, water-soluble, and gas ligands

• Selective Permeability

  • The hydrophobic and hydrophilic regions of plasma membranes aid the diffusion of some molecules and hinder the diffusion of others.
  • Recall that plasma membranes are amphiphilic; that is, they have hydrophilic and hydrophobic regions.
  • Lipid-soluble material with a low molecular weight can easily slip through the hydrophobic lipid core of the membrane.

• Phospholipids

  • A phospholipid is an amphipathic molecule which means it has both a hydrophobic and a hydrophilic component.
  • The lipid tails, on the other hand, are uncharged, nonpolar, and hydrophobic, or "water fearing."
  • A hydrophobic molecule repels and is repelled by water.
  • The formation of a micelle is a response to the amphipathic nature of fatty acids, meaning that they contain both hydrophilic and hydrophobic regions.
  • The hydrophobic tails associate with one another, forming the interior of the membrane.

• The Plasma Membrane and the Cytoplasm

  • A single phospholipid molecule consists of a polar phosphate "head," which is hydrophilic, and a non-polar lipid "tail," which is hydrophobic.
  • Unsaturated fatty acids result in kinks in the hydrophobic tails.
  • The hydrophobic tails associate with one another, forming the interior of the membrane.
  • The phospholipids are tightly packed together, while the membrane has a hydrophobic interior.
  • The hydrophobic tails associate with one another, forming the interior of the membrane.

• Functional Groups

  • Functional groups are usually classified as hydrophobic or hydrophilic depending on their charge or polarity.
  • An example of a hydrophobic group is the non-polar methane molecule.

• Regulating Protein Activity and Longevity

  • Methylation in the proteins negates the negative charge on it and increases the hydrophobicity of the protein.
  • Methylation on carboxylate side chains covers up a negative charge and adds hydrophobicity.

• Types of Receptors

  • Internal receptors, also known as intracellular or cytoplasmic receptors, are found in the cytoplasm of the cell and respond to hydrophobic ligand molecules that are able to travel across the plasma membrane.
  • Each cell-surface receptor has three main components: an external ligand-binding domain (extracellular domain), a hydrophobic membrane-spanning region, and an intracellular domain inside the cell.
  • In order to interact with the phospholipid fatty acid tails that form the center of the plasma membrane, many of the amino acids in the membrane-spanning region are hydrophobic in nature.
  • Hydrophobic signaling molecules typically diffuse across the plasma membrane and interact with intracellular receptors in the cytoplasm.

• Digestion and Absorption

  • Lipids are hydrophobic substances.
  • Bile contains bile salts, which have hydrophobic and hydrophilic sides.
  • The bile salts' hydrophilic side can interface with water, while the hydrophobic side interfaces with lipids, thereby emulsifying large lipid globules into small lipid globules.