Human Biology Chapter 2: Chemistry of Life Flashcards

This set of vocabulary flashcards covers the fundamental concepts of biological chemistry from Chapter 2 of Sylvia S. Mader’s Human Biology, including atomic structure, chemical bonding, the properties of water, and the four major classes of organic molecules.

Matter

Anything that has mass and takes up space, existing as solid, gas, liquid, or plasma.

Elements

Basic building blocks of matter that cannot be broken down by chemical means.

Atom

The smallest unit of an element that retains its physical and chemical properties.

Molecule

A structure formed when atoms bond together.

Neutrons

Neutral (uncharged) subatomic particles located in the nucleus of an atom.

Protons

Positively charged subatomic particles located in the nucleus of an atom.

Electrons

Negatively charged subatomic particles that orbit the nucleus in electron shells.

Atomic number

The number of protons in an atom, which differs for every element.

Mass number

The sum of the number of protons and neutrons in an atom's nucleus.

Atomic mass

The average atomic mass unit (AMU) for all isotopes of a specific atom.

Isotopes

Atoms of the same element with the same atomic number but a different number of neutrons, resulting in a different atomic mass.

Radioisotopes

Unstable isotopes that emit energy called radiation; they can be used for medical imaging or killing cancer cells.

Compounds

Molecules made of different types of atoms, such as $H_2O$.

Valence shell

The outer shell of an atom; atoms are most stable when this shell is filled with eight electrons.

Ionic bond

The attraction between a positive and negative ion, created when atoms donate or receive electrons to fill their valence shell.

Covalent bond

A bond created when atoms share electrons to fill their valence shells, with each atom contributing one electron to the shared pair.

Hydrogen bond

A relatively weak attraction between a slightly positive hydrogen and a slightly negative atom, usually nitrogen or oxygen.

Polar molecule

A molecule with an uneven distribution of charge, such as water, which has a partial negative charge on the oxygen side and partial positive charges on the hydrogen side.

Calorie

The amount of heat required to raise the temperature of $1\,g$ of water by $1^{\circ}C$.

Hydrophilic

Polar molecules that attract water.

Hydrophobic

Nonpolar molecules that do not attract water, such as vegetable oil.

Cohesion

The property of water molecules clinging to each other through hydrogen bonds.

Adhesion

The property of water molecules clinging to polar surfaces, such as the walls of blood vessels.

Acids

Substances that dissociate in water and release hydrogen ions ($H^+$).

Bases

Substances that take up hydrogen ions ($H^+$) or release hydroxide ions ($OH^-$).

pH scale

A measure of acidity or basicity ranging from $0$ to $14$, where $7$ is neutral.

Buffer

A solution that resists changes in pH when acids or bases are added, such as the carbonic acid and bicarbonate ions found in blood.

Dehydration reaction

A synthesis chemical reaction that removes water to link subunits together into macromolecules.

Hydrolysis reaction

A chemical reaction that adds water to break macromolecules down into their smaller subunits.

Monosaccharides

Simple carbohydrates made of a single sugar molecule with a carbon backbone of three to seven carbons.

Glucose

The most common monosaccharide ($C_6H_{12}O_6$) used as an immediate energy source in the body.

Polysaccharides

Complex carbohydrates that are long polymers of glucose subunits, including starch, glycogen, and cellulose.

Glycogen

A complex carbohydrate used for energy storage in animals.

Cellulose

A structural polysaccharide found in plant cell walls that cannot be digested by humans and is called "fiber."

Triglycerides

Lipids made of one glycerol and three fatty acids, functioning in energy storage, insulation, and cushioning.

Saturated fatty acids

Fatty acids that have no double covalent bonds between carbons and are usually solid at room temperature.

Unsaturated fatty acids

Fatty acids that have one or more double covalent bonds and are usually liquid at room temperature.

Phospholipids

The primary components of plasma membranes, consisting of a polar hydrophilic head and two nonpolar hydrophobic tails.

Steroids

Lipids made of four fused carbon rings, such as cholesterol, estrogen, and testosterone.

Amino acids

The subunits of proteins, each consisting of an amino group, a carboxyl group, and a variable R group.

Peptide bond

A polar covalent bond that links two amino acids together.

Denaturation

The irreversible change in a protein's three-dimensional shape caused by extreme heat or pH, leading to a loss of function.

Primary structure

The linear order or sequence of amino acids in a protein.

Nucleotides

The building blocks of nucleic acids, each composed of a phosphate, a 5-carbon sugar, and a nitrogenous base.

DNA (Deoxyribonucleic acid)

A double-stranded nucleic acid that stores genetic information and specifies the order of amino acids in proteins.

RNA (Ribonucleic acid)

A single-stranded nucleic acid that aids in the expression of genes and utilizes the sugar ribose.

ATP (Adenosine triphosphate)

A high-energy molecule and universal energy currency of cells that releases energy when the bond between the second and third phosphate is broken.