Seeley's Anatomy and Physiology: Chapter 2 - The Chemical Basis of Life

These flashcards cover the fundamental principles of chemistry as applied to human anatomy and physiology, including atomic structure, chemical bonding, types of reactions, energy, pH, and major organic macromolecules.

How are matter, mass, and weight defined?

Matter is anything that occupies space and has mass. Mass is the amount of matter in an object, and weight is the gravitational force acting on an object of a given mass.

What are the four most abundant elements in the human body by weight?

Oxygen ($65.0\%$), Carbon ($18.5\%$), Hydrogen ($9.5\%$), and Nitrogen ($3.3\%$).

What are the three major subatomic particles, and what are their charges and locations?

Protons have a positive charge and are in the nucleus. Neutrons have no charge (uncharged) and are in the nucleus. Electrons have a negative charge and move around the nucleus in an electron cloud.

What is the difference between the atomic number and the mass number?

The atomic number is the number of protons in each atom of an element. The mass number is the number of protons plus the number of neutrons in each atom.

What is an isotope?

Isotopes are two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons.

What is Avogadro's number, and what does it represent?

Avogadro's number is $6.022 \times 10^{23}$, which represents the number of entities (atoms, ions, or molecules) in $1$ mole of a substance.

What is the octet rule?

The tendency of atoms to combine with other atoms until each has $8$ electrons ($2$ electrons for hydrogen) in its valence shell.

How does an ionic bond differ from a covalent bond?

An ionic bond forms when electrons are transferred between atoms, creating oppositely charged ions (cations and anions). A covalent bond forms when atoms share one or more pairs of electrons.

What is the difference between a molecule and a compound?

A molecule is composed of two or more atoms chemically combined to form an independent unit. A compound is a substance resulting from the chemical combination of two or more different types of atoms.

What creates a hydrogen bond?

A hydrogen bond is formed when the positively charged hydrogen of one polar molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another polar molecule.

What is solubility and dissociation?

Solubility is the ability of one substance to dissolve in another. Dissociation (or separation) is the process where ions in an ionic compound separate from one another when dissolved in water.

What is the difference between an electrolyte and a nonelectrolyte?

Electrolytes are cations and anions that dissociate in water and have the capacity to conduct an electric current. Nonelectrolytes are molecules that do not dissociate and do not conduct electricity.

How are synthesis and decomposition reactions related to metabolism?

Synthesis reactions (anabolism) combine reactants to form larger products. Decomposition reactions (catabolism) break down larger reactants into smaller products. Metabolism is the sum of all anabolic and catabolic reactions in the body.

What occurs in dehydration and hydrolysis reactions?

In a dehydration reaction, water is a product of a synthesis reaction. In a hydrolysis reaction, water is split and added to the products of a decomposition reaction.

What defines an oxidation-reduction (redox) reaction?

Oxidation is the loss of an electron by an atom, while reduction is the gain of an electron. These reactions result from the exchange of electrons between reactants.

What is the difference between potential and kinetic energy?

Potential energy is stored energy that could do work. Kinetic energy is the form of energy that is actually doing work and moving matter.

What is activation energy, and how do catalysts affect it?

Activation energy is the minimum amount of energy the reactants must have to start a chemical reaction. Catalysts (like enzymes) increase the rate of reactions by lowering the activation energy.

How is a solution different from a suspension and a colloid?

A solution is a uniform mixture of solute and solvent. A suspension contains materials that separate unless physically blended. A colloid is an uneven distribution of particles that are small enough that they do not settle out.

How is an acid defined compared to a base?

An acid is a proton ($H^+$) donor. A base is a proton acceptor; many bases release hydroxide ions ($OH^-$) when they dissociate.

What is the pH scale, and what is the normal range for human blood?

The pH scale ranges from $0$ to $14$ to represent $H^+$ concentration ($7$ is neutral). The normal pH range for human blood is $7.35$ to $7.45$.

What is the purpose of a buffer in the body?

Buffers are chemicals that resist changes in pH when either acids or bases are added to a solution, helping maintain homeostatic pH ranges.

What are isomers in organic chemistry?

Isomers are molecules that have the same number and types of atoms but differ in their three-dimensional arrangement, such as glucose, fructose, and galactose.

What is the structure of a triglyceride?

Triglycerides consist of one glycerol molecule and three fatty acids.

How do saturated and unsaturated fatty acids differ?

Saturated fatty acids contain only single covalent bonds between carbon atoms. Unsaturated fatty acids have one or more double covalent bonds between carbon atoms.

What are the four levels of protein structure?

Primary (amino acid sequence), Secondary (folding into sheets or helices via hydrogen bonds), Tertiary (large-scale folding driven by environment and disulfide bridges), and Quaternary (association of two or more proteins).

Distinguish between the lock-and-key and induced fit models of enzymes.

The lock-and-key model suggests reactants fit into an enzyme's active site rigidly. The induced fit model suggests the enzyme changes shape slightly to better fit the reactants.

What are the three components of a nucleotide?

A monosaccharide (sugar), a nitrogenous base, and a phosphate group.

What are the structural differences between DNA and RNA?

DNA contains deoxyribose, has the base thymine, and is double-stranded. RNA contains ribose, has the base uracil, and is typically single-stranded.

Why is ATP called the 'energy currency' of cells?

Adenosine triphosphate (ATP) is capable of both storing and providing energy for nearly all chemical reactions within cells, particularly through the cleavage of its 'high-energy' phosphate bonds.