The Molecules of Life practice flashcards

Vocabulary flashcards covering the basic chemical concepts of biology, including atomic structure, chemical bonding, water properties, and the four major classes of organic molecules.

Element

A substance that consists of only one type of atom and cannot be chemically separated into simpler parts.

Living matter elements

The six primary elements that compose living matter: Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Phosphorus (P), and Sulfur (S).

Atom

The basic unit of matter, consisting of a central nucleus and an electron cloud.

Protons

Positively charged particles located within the nucleus of an atom.

Neutrons

Uncharged particles located within the nucleus of an atom.

Electrons

Negatively charged particles that form a cloud arranged in shells of different energy levels around the nucleus.

Atomic number

The number of protons in the nucleus of an atom.

Mass number

The sum of the protons and neutrons in an atom.

Isotopes

Atoms of an element that have different numbers of neutrons.

Atomic mass

The average of the mass numbers of all the atoms of a specific element.

Octet rule

The principle that biological molecules are most stable when they have 8 electrons in their outer shell.

Valence electrons

The electrons located in the outer shell of an atom.

Ion

An atom that has gained or lost one or more electrons.

Anions

Negatively charged ions that have gained one or more electrons.

Cations

Positively charged ions that have lost one or more electrons.

Ionic bonds

Chemical bonds formed due to the attraction between negative and positive charges, producing salts or electrolytes.

Covalent bonds

Chemical bonds that form when atoms share electrons.

Molecule

Two or more atoms joined together by covalent bonds.

Compound

A molecule that contains atoms of different elements, such as $H_2O$.

Non-polar covalent bond

A type of covalent bond characterized by the equal sharing of electrons between atoms.

Polar covalent bond

A type of covalent bond characterized by the unequal sharing of electrons, where one atom is more electronegative than the other.

Hydrogen bonds

Weak bonds formed when a hydrogen atom in a polar molecule is attracted to an electronegative atom in the same or another polar molecule.

Synthesis reaction

A chemical reaction where starting components combine to form a product, represented as $A + B \rightarrow AB$.

Decomposition reaction

A chemical reaction where a compound is broken down into simpler parts, represented as $AB \rightarrow A + B$.

Enzymes

Biological catalysts that are required to break covalent bonds at biological temperatures.

Enzyme Substrate

The specific substance upon which an enzyme acts.

Active site

The specific region of an enzyme where the substrate binds and the reaction occurs.

Hydrophilic

"Water loving" substances that are polar or charged and dissolve well in water.

Hydrophobic

"Water fearing" substances that are non-polar and do not dissolve in water.

pH

A measure of acidity based on the concentration of $H^+$ ions.

Acids

Substances that increase the $H^+$ concentration and have a $pH < 7$.

Bases

Substances that decrease the $H^+$ concentration and have a $pH > 7$.

Buffer

A chemical that helps maintain a relatively constant pH by releasing or combining with $H^+$ ions.

Polymers

Large molecules created by joining individual monomer subunits.

Carbohydrates

A group of organic molecules including sugars and starches, containing carbon, hydrogen, and oxygen in a $1:2:1$ ratio.

Monosaccharide

The basic unit of carbohydrates, including 5-carbon sugars like ribose and 6-carbon sugars like glucose.

Structural isomers

Molecules with the same set of atoms but in a different arrangement, resulting in distinct properties.

Disaccharides

Carbohydrates composed of two monosaccharides, such as sucrose, lactose, and maltose.

Dehydration synthesis

A chemical reaction that forms a covalent bond between two molecules by removing a water molecule.

Hydrolysis

A chemical reaction that breaks a covalent bond by adding a water molecule.

Polysaccharides

Large chains of monosaccharides, including cellulose, starch, glycogen, and dextran.

Triglycerides

The most common simple lipids, consisting of three fatty acids linked to a glycerol molecule.

Saturated fatty acids

Fatty acids with no double bonds that are typically solid at room temperature because their tails pack tightly.

Unsaturated fatty acids

Fatty acids containing double bonds that create kinks, preventing tight packing and making them liquid at room temperature.

Phospholipids

Compound lipids containing a hydrophilic phosphate group and hydrophobic fatty acid tails, essential for cytoplasmic membranes.

Steroids

Lipids characterized by a four-ring structure, which include sterols like cholesterol and hormones like testosterone.

Amino Acids

The subunits of proteins, consisting of a central carbon, a carboxyl group, an amino group, and a variable side chain (R group).

Peptide Bonds

Covalent bonds formed by dehydration synthesis that hold amino acids together in a polypeptide.

Primary structure

The specific sequence and number of amino acids in a protein's polypeptide chain.

Secondary structure

Localized coiling or folding of a polypeptide, such as an alpha-helix or beta-pleated sheet, primarily due to hydrogen bonding.

Tertiary structure

The overall 3-dimensional shape of a folded polypeptide caused by interactions between R groups.

Quaternary structure

The structure resulting from the association between multiple polypeptide chains.

Protein domain

A stable substructure within a protein that is associated with a specific function.

Protein Denaturation

The loss of a protein’s characteristic shape, making it nonfunctional, often caused by high temperature or extreme pH.

Nucleotides

The monomers of nucleic acids, composed of a pentose sugar, a phosphate group, and a nucleobase.

Purines

Nucleobases with a two-fused-ring structure, specifically adenine (A) and guanine (G).

Pyrimidines

Nucleobases with a single ring structure, including cytosine (C), thymine (T), and uracil (U).

DNA (deoxyribonucleic acid)

A double-stranded helix where the sugar is deoxyribose and strands are held together by hydrogen bonds between complementary base pairs (A-T and C-G).

RNA (ribonucleic acid)

A mostly single-stranded nucleic acid involved in protein synthesis that contains the sugar ribose and the base uracil instead of thymine.

ATP (Adenosine Triphosphate)

The energy currency of the cell, composed of adenosine and three negatively charged phosphate groups.