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Questions and Answers
Which type of interaction is primarily responsible for the formation of a lipid bilayer in an aqueous solution?
Which type of interaction is primarily responsible for the formation of a lipid bilayer in an aqueous solution?
- Hydrogen bonds between water and lipid tails
- Van der Waals forces between water molecules
- Hydrophobic interactions between lipid tails (correct)
- Electrostatic/ionic bonds between lipid heads
What is the significance of the 104.5 degree bond angle in a water molecule for its properties?
What is the significance of the 104.5 degree bond angle in a water molecule for its properties?
- It allows water to form exactly two hydrogen bonds per molecule.
- It results in a bent molecular shape and a permanent dipole. (correct)
- It contributes to water's linear shape, preventing dipole formation.
- It maximizes the potential for ionic bonding.
How does the arrangement of fatty acid tails in micelles contribute to entropy?
How does the arrangement of fatty acid tails in micelles contribute to entropy?
- It increases entropy by sequestering the tails away from water. (correct)
- It maintains entropy by allowing water molecules to form hydrogen bonds.
- It decreases entropy by increasing the order of water molecules.
- It reduces entropy by maximizing the surface area of the tails exposed to water.
How does the electronegativity difference between oxygen and hydrogen contribute to the properties of water?
How does the electronegativity difference between oxygen and hydrogen contribute to the properties of water?
Which statement accurately describes the behavior of amphipathic molecules in water?
Which statement accurately describes the behavior of amphipathic molecules in water?
Why do non-polar substances, such as methane, not dissolve in water?
Why do non-polar substances, such as methane, not dissolve in water?
What is the role of hydrogen bonds in determining the properties of water?
What is the role of hydrogen bonds in determining the properties of water?
How do proteins utilize "hydration shells" to interact with water?
How do proteins utilize "hydration shells" to interact with water?
Considering the types of bonds, what is the nature of Van der Waals interactions?
Considering the types of bonds, what is the nature of Van der Waals interactions?
If a molecule is described as hydrophilic, what characteristic would you expect it to possess?
If a molecule is described as hydrophilic, what characteristic would you expect it to possess?
Flashcards
Electrostatic/Ionic bonds
Electrostatic/Ionic bonds
Occur between ions of opposite charges.
Hydrogen Bonds
Hydrogen Bonds
Bond between H and another electronegative molecule like oxygen (O-H).
Hydrophobic Interactions
Hydrophobic Interactions
Non-polar molecules bond in a polar solvent. Example: Formation of bilayer.
Van der Waals
Van der Waals
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Hydrophilic
Hydrophilic
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Hydrophobic
Hydrophobic
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Amphipathic
Amphipathic
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Water Bond Angle
Water Bond Angle
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Study Notes
- General notes for biochemistry
Types of Bonds
- Electrostatic/Ionic bonds occur between ions of opposite charges.
- Hydrogen bonds form between hydrogen and another electronegative molecule, such as oxygen in O-H.
- Hydrophobic interactions involve non-polar molecules bonding in a polar solvent; for example, bilayer formation.
- Van der Waals bonds include long dispersion forces, with temporary dipole-dipole moments in non-polar substances and dipole-dipole moments in polar molecules.
Water
- Water has a bond angle of 104.5 degrees.
- Water has a permanent dipole.
- Oxygen is more electronegative than hydrogen in water molecules.
- Each water molecule can form 4 hydrogen bonds: two O-H bonds from the two lone pairs on oxygen, and one each from the two hydrogens.
Hydrophilic substances
- Hydrophilic substances easily dissolve in water.
- Examples of hydrophilic functional groups include -OH, NH3+, and COO-.
Hydrophobic substances
- Hydrophobic substances do not dissolve in water.
- The presence of long hydrocarbon chains, aliphatic rings, etc., leads to hydrophobicity.
Amphipathic substances
- Amphipathic molecules have both polar and non-polar parts.
- Fatty acids are amphipathic: the phosphate head is charged/polar while the fatty acid tails are non-polar.
Non-polar substances
- Non-polar substances like oxygen, nitrogen, carbon dioxide, and methane do not dissolve in water.
Fatty acids and water molecules
- Fatty acids surrounded by water form a H2O cage, decreasing entropy.
- In micelles, fatty acid tails are sequestered inside, increasing entropy.
Proteins and water
- Proteins with polar and non-polar regions attract complementary opposites in water, forming a "hydration" shell.
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