Atoms and Molecules of Life - Slide 3

Vocabulary flashcards covering atomic structure, chemical bonding, water properties, macromolecules, and origins of organic molecules.

Matter

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

Element

A basic building block of matter that cannot be broken down by chemical means.

Atom

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

Proton

A positively charged subatomic particle located in the nucleus of an atom with an atomic mass unit of $1$.

Neutron

A neutral (uncharged) subatomic particle located in the nucleus of an atom with an atomic mass unit of $1$.

Electron

A negatively charged subatomic particle that orbits around the nucleus of an atom in electron shells.

Isotope

Atoms of the same element that have the same atomic number but a different number of neutrons, differing in atomic mass.

Radioisotope

An unstable isotope that emits energy called radiation.

Molecule

A group of atoms bonded together.

Compound

A molecule made of two or more different types of atoms.

Valence shell

The outermost electron shell of an atom.

Ionic bond

The chemical bond formed by the electrostatic attraction between oppositely charged ions.

Covalent bond

A chemical bond formed when atoms share pairs of electrons to fill their valence shells.

Hydrogen bond

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

Calorie

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

Hydrophilic

Molecules that are polar and attract water, dissolving readily in solution.

Hydrophobic

Molecules that are nonpolar, do not attract water, and do not dissolve in water.

Cohesion

The property of water molecules clinging to each other through hydrogen bonds, allowing water to flow freely without separating.

Adhesion

The property of water molecules clinging to other surfaces, such as blood vessel walls.

Extraterrestrial hypothesis

The proposal that meteorites brought organic carbon, including amino acids and nucleic acid bases, to Earth.

Deep-sea vent hypothesis

The proposal that biologically important organic molecules formed in the temperature gradient between extremely hot vent water and cold ocean water.

Dehydration reaction

A type of synthesis chemical reaction that removes water to link subunit monomers together into macromolecules.

Hydrolysis reaction

A chemical reaction that breaks macromolecules down into their subunits through the addition of water.

Peptide bond

The covalent bond that links amino acid monomers together to form a polypeptide or protein.

Phosphodiester bond

The covalent bond that connects nucleotide monomers together to form nucleic acids.

Glycosidic bond

The covalent bond that links monosaccharide monomers together to form polysaccharides.

Pentose

A five-carbon monosaccharide, such as ribose ($\text{C}_5\text{H}_{10}\text{O}_5$) or deoxyribose ($\text{C}_5\text{H}_{10}\text{O}_4$).

Hexose

A six-carbon monosaccharide, such as glucose ($\text{C}_6\text{H}_{12}\text{O}_6$).

Lipids

Nonpolar organic molecules that are very insoluble in water and comprise about $40\%$ of the organic matter in the average human body.

Phospholipid

An amphipathic lipid consisting of a hydrophilic head group and hydrophobic fatty acyl tails that forms cellular membrane bilayers.

DNA

Deoxyribonucleic acid, a nucleic acid consisting of two complementary strands in a double helix that encodes genetic information.

RNA

Ribonucleic acid, a single-stranded nucleic acid that decodes DNA into instructions for linking amino acids into polypeptide chains.

Essential amino acids

The $9$ amino acids that cannot be synthesized by the human body and must be obtained from the diet.

Nonessential amino acids

The $11$ amino acids that can be synthesized by the human body.