Chapter 2 - The Chemical Basis of Life

Vocabulary practice flashcards covering Chapter 2: The Chemical Basis of Life, including atomic structure, chemical bonds, reactions, macromolecules, pH, and buffers.

Atom

The smallest unit of matter that retains the chemical properties of an element.

Transverse Plane

A horizontal body plane that divides the body into superior (upper) and inferior (lower) portions.

Subatomic Particles

The three constituent particles of an atom: positively charged protons and uncharged neutrons located in the nucleus, and negatively charged electrons orbiting the nucleus.

Element

A specific type of atom defined by its number of protons, with Hydrogen (H), Carbon (C), and Nitrogen (N) being among the most abundant in the human body.

Molecule

A particle formed when two or more atoms join together and share electrons via covalent bonds to achieve eight electrons in their outer shell.

Covalent Bond

A chemical bond formed when atoms share electrons in order to satisfy the octet rule.

Ion

An atom that has an unequal number of electrons and protons, giving it an overall positive or negative electrical charge.

Cation

A positively charged ion formed when an atom loses or transfers one or more electrons, resulting in fewer electrons than protons.

Anion

A negatively charged ion formed when an atom gains one or more electrons, resulting in more electrons than protons.

Ionic Bond

A chemical attraction between oppositely charged ions in close proximity created after an electron transfer.

Salt

An ionic compound composed of a cation other than $H^+$ and an anion other than $OH^-$ (such as $NaCl$) that dissociates into separate ions in water.

Salt Dissociation

The process in which an ionic compound like sodium chloride ($NaCl$) separates into hydrated cations ($Na^+$) and anions ($Cl^-$) when placed in water.

Chemical Reaction

The forming or breaking of chemical bonds to rearrange reactant atoms into new products without gaining or losing any atoms.

Hydrolysis

A chemical reaction in which $H_2O$ is consumed as a reactant to break large polymers down into smaller monomers.

Dehydration Synthesis

A chemical reaction in which $H_2O$ is produced as a product when joining smaller monomers together to build larger polymers.

Macromolecules

Exceptionally large biological molecules consisting of thousands or millions of atoms formed by joining monomers into polymers.

Nucleic Acids

Biological macromolecules, including DNA and RNA, composed of nucleotide monomers that carry genetic material.

Nucleotide

The monomer of nucleic acids, consisting of a phosphate group, a sugar, and a nitrogen base (Adenine, Thymine, Cytosine, Guanine, or Uracil).

Adenosine Triphosphate (ATP)

The primary energy molecule of the human body that releases large amounts of stored energy when its phosphate bonds are broken, yielding ADP and inorganic phosphate.

Carbohydrates

Biological macromolecules composed of monosaccharide monomers that serve as primary cellular energy sources, such as glycogen.

Monosaccharide

The monomer building block of carbohydrates, also known as simple sugars, which includes glucose, fructose, and galactose.

Glucose ($C_6H_{12}O_6$)

A simple sugar used by cells during cellular respiration to synthesize ATP for cellular energy.

Triglyceride

A lipid composed of 1 glycerol and 3 fatty acids that accounts for 95% of fat in humans, functioning in energy storage and insulation.

Phospholipid

A lipid consisting of 1 polar, hydrophilic phosphate head and 2 nonpolar, hydrophobic fatty acid tails, serving as the main component of cell membranes.

Proteins

Biological macromolecules made of amino acid monomers whose functional shape determines their biological role, such as collagen and enzymes.

Polypeptide Chain

A chain of amino acids linked together that subsequently folds into a functional protein.

Denaturation

The loss of a protein's functional 3D shape and biological function due to extreme temperature or pH.

pH

A relative measurement of the concentration of hydrogen ions ($H^+$) in a solution.

Acid

A proton donor with a pH under 7 that releases hydrogen ions ($H^+$) when dissociated in water (e.g., $HCl \rightarrow H^+ + Cl^-$).

Base

A proton acceptor with a pH over 7 that binds to $H^+$ or releases hydroxide ions ($OH^-$) when dissociated in water (e.g., $NaOH \rightarrow Na^+ + OH^-$).

pH Scale

A scale ranging from 0 to 14 measuring $H^+$ concentration, where values under 7 indicate acidity, 7 is neutral, and values over 7 indicate alkalinity.

Buffer

A chemical that resists or reduces major fluctuations in the pH of a solution, maintaining normal human blood pH between 7.35 and 7.45.

Bicarbonate Ion ($HCO_3^-$)

An essential physiological buffer in human blood that binds to free $H^+$ ions to neutralize acid and stabilize pH.

Buffer Mechanism

The process by which buffer particles bind to added $H^+$ ions in an acidic solution to limit free $H^+$ and resist pH changes.