Chapter 2.1

Sugars, DNA, RNA, and most proteins.

Hydrogen bonds.

The close multi-point contacts required for strong binding provide great specificity.

Carbon (C), hydrogen (H), nitrogen (N), and oxygen (O).

7.0, which is considered neutral.

They are also energy sources.

Nearly all of the acetic acid is present as acetate ion.

A complex of about 90 macromolecules, including protein and RNA molecules.

Molecules that contain polar bonds and can form hydrogen bonds with water, such as alcohols.

Because all of the H atoms are covalently linked to C atoms by largely nonpolar bonds, preventing effective hydrogen bonding.

Even the simplest cell has vastly more complicated chemistry than any other known chemical system.

Water forms competing interactions with the involved molecules, greatly weakening the strength of these bonds.

They allow proteins to function as enzymes.

Polymers constructed from small organic building blocks.

Because they are typically 100 times stronger than the thermal energies within a cell.

Macromolecules are enormous polymeric molecules that enable cells and organisms to grow, reproduce, and perform other life functions.

Proteins perform thousands of distinct functions, including acting as enzymes, building structural components, serving as signaling devices, and acting as molecular motors.

Because it dissociates readily in aqueous solution to form Na+ ions and OH- ions.

The slight positive charge associated with the hydrogen atom is electrically attracted to the slight negative charge of the oxygen atom.

Because the proton of a hydronium ion can be passed readily to many types of molecules in cells, altering their character.

Their particular folding into a stable three-dimensional shape.

Nearly 4000 different kinds.

70%.

Sugars, fatty acids, nucleotides, and amino acids.

The hydrogen atom can dissociate and associate with the oxygen atom of a water molecule, forming a hydronium ion (H3O+).

Enzymes facilitate the stepwise polymerization of monomers into a long chain by performing the same reaction repeatedly.

Strong acids easily lose their protons, while weak acids hold on to their protons more tightly.

Macromolecules produced as linear polymers of amino acids (proteins) or nucleotides (DNA and RNA).

Through covalent bonds.

Hydrophilic, meaning water-loving.

Hydrogen bonds, electrostatic attractions (ionic bonds), van der Waals attractions, and the hydrophobic force.

The energies of noncovalent attractions can sum to create a strong force between two separate molecules.

The strength of binding depends on the number of noncovalent bonds formed.

Weak bases have a weak tendency to reversibly accept a proton from water, helping to maintain pH balance.

Hydrogen bonds, ionic bonds, van der Waals interactions, and hydrophobic interactions.

Carbon can form four covalent bonds with other atoms and can join to other carbon atoms through stable covalent C–C bonds to form chains and rings.

Ribosomes are central to the machinery that the cell uses to make proteins.

They allow molecules to recognize each other and reversibly associate.

Because hydrogen bonds link water molecules together, giving it a high boiling point and high surface tension.

Acids.

Red elements constitute 99% of the atoms in the human body, blue elements represent about 0.9%, green elements are required in trace amounts, and the necessity of yellow elements is unclear.

Buffers are weak acids and bases that can release or take up protons near pH 7, keeping the cell environment relatively constant.

The molecule becomes a flexible chain and loses its biological activity.

Life depends on chemical reactions in aqueous solutions and is based overwhelmingly on carbon compounds.

Small organic molecules that can be covalently linked into long chains to form polymers.

A large fraction of the cell mass.

One kilojoule (kJ) is equal to 0.239 kilocalories (kcal).

The amino group is a weak base that can generate OH- by taking a proton from water.

Macromolecules dominate the cell's weight.

Proteins are made of amino acids, nucleic acids are made of nucleotides, and polysaccharides are made of sugars.

Covalent bonds.

Bringing any two nonpolar surfaces together reduces their contact with water.

It is a special form of polar interaction where an electropositive hydrogen atom is shared by two electronegative atoms.

A reaction in which one molecule of water is lost with each subunit added to a growing polymer chain.

Macromolecules.

The product of [OH-] × [H3O+] is always 10^-14 (moles/liter)^2.

Na+, K+, Mg2+, Ca2+, and Cl-.

They can act as monomer subunits for macromolecules, energy sources, and have various other roles.

Animals were believed to contain a Vital Force or 'animus' responsible for their distinctive properties.

When the atoms involved are fully charged or ionized.

Emergent properties are complex characteristics that arise from interlinked networks of chemical reactions in cells.

Amino acids and the proteins they form.

They allow macromolecules to assemble into intricate machines with multiple moving parts.

Sugars, fatty acids, amino acids, and nucleotides.

Polysaccharides, proteins, and nucleic acids.

Molecules that are uncharged, form few or no hydrogen bonds, and do not dissolve in water.

Hydrophobic forces are central to the proper folding of protein molecules.

A base is any molecule capable of accepting a proton from a water molecule.

A force caused by the pushing of nonpolar surfaces out of the hydrogen-bonded water network.

The precise order of subunits is critical to the function of the polymer and is not assembled at random.

Noncovalent bonds constrain the shapes of macromolecules by forming between different parts of the same molecule, leading to a highly preferred conformation.

Organic molecules are carbon compounds made by cells, in contrast to inorganic molecules like water.

The study of carbon compounds.

Fluctuations in the distribution of electrons in every atom, generating a transient attraction when atoms are in close proximity.

By the amount of energy that must be supplied to break it, expressed in kilojoules per mole (kJ/mole) or kilocalories per mole (kcal/mole).

96.5%.

A distinctive and restricted set of small carbon-based molecules.

Condensation reactions form polymers by losing water and are energetically unfavorable, while hydrolysis reactions break down polymers by adding water and are energetically favorable.

The four major families are proteins, nucleic acids, large polysaccharides, and small organic molecules.

Noncovalent chemical bonds have less than 1/20 the strength of a covalent bond.

Common chemical groups include methyl (–CH3), hydroxyl (–OH), carboxyl (–COOH), carbonyl (–C=O), phosphate (–PO3^2-), sulfhydryl (–SH), and amino (–NH2) groups.