Biology and the Chemical Basis of Life

A set of vocabulary flashcards covering the basics of biology, chemical foundations of cells, organizational levels, and the structure of biological macromolecules.

Biology

The scientific study of living things, also known as organisms, derived from the Greek words "bios" (life) and "logos" (study).

Organism

A living entity that consists of one or more cells, engages in metabolism, senses and responds to its environment, and has heritable instructions encoded in DNA.

Metabolism

The capacity to obtain and convert energy from surroundings and use energy to maintain itself, grow, and produce more cells.

DNA (Deoxyribonucleic acid)

A nucleic acid that serves as the signature molecule of a cell, holding instructions for assembling a variety of proteins from amino acids.

Producers

Self-feeding organisms, such as plants, that acquire energy and simple raw materials from environmental sources (e.g., through photosynthesis) to make their own food.

Consumers

Organisms, including animals, most fungi, and many protists or bacteria, that cannot make their own food and get energy/nutrients by eating producers and other organisms.

Nutrient

A type of atom or molecule that has an essential role in growth and survival and that an organism cannot make for itself.

Atom

The smallest unit of an element that still retains the characteristic properties of that element.

Proton ($p^+$)

A positively charged particle of the atomic nucleus; a proton without an electron zipping around it is a hydrogen ion ($H^+$).

Electron ($e^-$)

A negatively charged particle that can occupy a volume of space (orbital) around an atomic nucleus and can be shared or transferred among atoms.

Neutron

An uncharged particle of the nucleus found in all atoms except hydrogen.

Element

A fundamental form of matter that occupies space, has mass, and cannot be broken apart into a different form of matter by ordinary physical or chemical means.

Isotope

One of two or more forms of an element's atoms that differ in their number of neutrons.

Ion

An atom that has gained or lost one or more electrons, thus becoming negatively or positively charged.

Molecule

A unit of matter in which two or more atoms of the same or different elements are bonded together.

Compound

A molecule composed of two or more different elements in unvarying proportions, such as water ($H_2O$).

Hydrophilic substance

A polar molecule that can readily dissolve in water; "water-loving" substances.

Hydrophobic substance

A nonpolar molecule that strongly resists dissolving in water; "water-dreading" substances.

Acid

A substance that donates Hydrogen ($H^+$) when dissolved in water.

Base

A substance that accepts hydrogen when dissolved in water.

Salt

A compound that releases ions other than $H^+$ or $OH^-$ when dissolved in water.

Organic Compounds

Molecules containing carbon and at least one hydrogen atom.

Carbohydrates

The most abundant biological molecules of life, consisting of carbon, hydrogen, and oxygen in a ratio of $1:2:1$ ($CH_2O$).

Monosaccharide

The simplest carbohydrate, meaning "one sugar monomer," such as ribose and deoxyribose.

Oligosaccharide

Short-chain carbohydrates consisting of "a few" sugar units, such as disaccharides like lactose and sucrose.

Polysaccharide

Complex carbohydrates consisting of straight or branched chains of many sugar monomers, such as cellulose, starch, and glycogen.

Triglycerides

Neutral fats that have a glycerol head and three fatty acid tails, serving as major energy reservoirs.

Phospholipids

The main materials of cell membranes, consisting of a glycerol backbone, two fatty acid tails, and a hydrophilic head with a phosphate group.

Sterols

Lipids with no fatty acids that have a rigid backbone of four fused carbon rings, such as cholesterol.

Primary protein structure

The sequence of different kinds of amino acids along a polypeptide chain.

Secondary protein structure

Local regions along a polypeptide chain that twist and fold into helical coils, sheet-like arrays of strands, and loops.

Tertiary protein structure

A polypeptide chain or parts of it organized into domains, which are structurally stable, compact units.

Quartenary protein structure

Consists of two or more polypeptide chains joined by hydrogen bonds, covalent bonds, and disulfide bridges.

Fibrous proteins

Proteins with a stable structure where polypeptide chains form long strands; they are insoluble in water and have structural functions (e.g., collagen, keratin).

Globular proteins

Proteins with a relatively unstable structure where polypeptide chains "roll up" into spherical shapes; they are soluble in water and have metabolic functions (e.g., enzymes, antibodies).

Denaturation

The breaking of weak bonds of a protein that disrupts its three-dimensional shape, often caused by changes in temperature or pH.

Ribose

The pentose (five-carbon) sugar found in RNA.

Deoxyribose

The pentose (five-carbon) sugar found in DNA.

Purine

A double-ringed nitrogenous base found in DNA and RNA, specifically Adenine (A) and Guanine (G).

Pyrimidine

A single-ringed nitrogenous base found in DNA and RNA, specifically Cytosine (C), Thymine (T), and Uracil (U).

Anti-parallel

The physical orientation of DNA where the two sugar-phosphate strands are in opposite directions.

mRNA (Messenger RNA)

RNA that provides information for making proteins.

tRNA (Transfer RNA)

RNA that brings amino acids, described as raw materials, to the protein factories.

rRNA (Ribosomal RNA)

RNA found in ribosomes where proteins are made.