Biology Lecture 2 - Non-covalent bonds and reaction concepts

Flashcards cover non-covalent bond types and strengths, hydrogen bonding concepts (donor/acceptor, ammonia-water examples), hydrophobic interactions and membranes, and basic chemistry aspects (equilibrium, reversibility, and polarity) discussed in Biology Lecture 2.

Which four types of non-covalent bonds are highlighted in Biology Lecture 2?

Electrostatic (ionic) bonds, hydrogen bonds, van der Waals interactions, and hydrophobic interactions.

Which non-covalent bonds are typically strongest according to the notes?

Electrostatic/ionic bonds and hydrophobic interactions are usually the strongest, followed by hydrogen bonds, then van der Waals.

Are hydrophobic interactions true bonds?

No. Hydrophobic interactions are not bonds; they are non-covalent interactions driven by molecules avoiding water.

What is required for a hydrogen bond to form between two molecules?

A hydrogen must be covalently bonded to a donor atom and interact with an electronegative acceptor atom with lone pairs.

In a hydrogen bond, what is the donor?

The atom covalently bonded to hydrogen.

In a hydrogen bond, what is the acceptor?

The electronegative atom with lone pairs that attracts the hydrogen.

Can ammonia act as both a hydrogen bond donor and acceptor depending on orientation?

Yes; ammonia can donate or accept hydrogen bonds depending on the arrangement with another molecule like water.

According to the example in the notes, how many hydrogen bonds can ammonia and water form together?

Up to seven hydrogen bonds between the two molecules in the depicted arrangement.

Can nitrogen form double acceptor hydrogen bonds?

Yes; nitrogen (as in ammonia) can sometimes attract two hydrogens at once, forming two, though usually weaker, bonds.

Are electrostatic bonds and ionic bonds the same concept in biology?

Yes; in biology these terms are used interchangeably to refer to attractions between charged species.

What drives the formation of membranes in water?

Hydrophobic interactions between phospholipid tails hide from water, driving bilayer formation.

Why do membranes stay intact in aqueous environments but dissociate in oil?

In water, hydrophobic tails cluster to hide from water; in oil (nonpolar environments) there is no driving force to keep them together.

How do biological reactions relate to equilibrium?

Most biological reactions proceed toward a state of equilibrium, not necessarily 100% products; both reactants and products persist.

Are most biological reactions reversible?

Yes; most are reversible, though some appear irreversible if a large amount of energy is required to reverse them.

What determines whether a covalent bond is polar or nonpolar?

The electronegativity difference between the two atoms; equal electronegativity yields nonpolar covalent bonds, unequal yields polar covalent bonds.