Unit 2- Atoms, Molecules, and Water

These flashcards cover key vocabulary terms and definitions related to the structure of atoms, molecules, and the chemistry of water, essential for understanding biological molecules and their interactions.

Atom

The basic unit of matter made up of protons, neutrons, and electrons.

Proton

A subatomic particle with a positive charge found in the nucleus of an atom.

Neutron

A subatomic particle that is neutral and found in the nucleus of an atom.

Electron

A subatomic particle with a negative charge that orbits the nucleus of an atom.

Isotope

Atoms of the same element that have different numbers of neutrons.

Ion

An atom or molecule that has gained or lost electrons, resulting in a net charge.

Covalent Bond

A chemical bond formed by the sharing of electrons between atoms.

Ionic Bond

A chemical bond formed through the transfer of electrons from one atom to another, creating charged ions.

Hydrogen Bond

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Van der Waals Forces

Weak attractions between molecules or parts of molecules that result from transient local partial charges.

Polarity

The distribution of electrical charge over the atoms joined by the bond, making one side partially negative and the other partially positive.

Cohesion

The tendency of water molecules to stick to each other due to hydrogen bonding.

pH

A scale used to specify the acidity or basicity of an aqueous solution.

Carbon

The most versatile element, capable of forming four covalent bonds with various structures.

Isomer

Compounds with the same chemical formula but different structures and biological functions.

Amino Acid

The monomer unit of proteins, linked by peptide bonds.

Peptide Bond

A covalent bond that links amino acids together in a protein.

Denaturation

The process in which a protein loses its native shape and, as a result, its function.

Nucleotide

The monomer unit of nucleic acids, consisting of a sugar, phosphate group, and nitrogenous base.

Phosphodiester Bond

The bond that links nucleotides together in a nucleic acid.

DNA Double Helix

The structure formed by two strands of DNA held together by hydrogen bonds between complementary nitrogenous bases.

Monosaccharides

Simple sugars, such as glucose and fructose, that provide quick energy.

Disaccharides

Carbohydrates formed from two monosaccharide units, such as sucrose and lactose.

Polysaccharides

Complex carbohydrates formed from many monosaccharide units, including starch, glycogen, and cellulose.

Glycosidic Bond

A covalent bond that joins monosaccharides together, formed by dehydration synthesis and broken by hydrolysis.

Primary function of Carbohydrates

Energy storage, primarily in the C
–
H bonds.

Carbohydrate's role in Structural Support

Provides structural support, such as cellulose in plant cell walls.

Lipids

A diverse group of hydrophobic, nonpolar molecules that are not true polymers.

Fatty Acids

Long hydrocarbon chains that are a fundamental component of many lipids, held together by Van der Waals forces.

Saturated Fats

Fats with hydrocarbon chains containing no double bonds, resulting in straight chains that pack tightly and are solid at room temperature.

Unsaturated Fats

Fats with hydrocarbon chains containing one or more double bonds, creating kinks that prevent tight packing, making them liquid at room temperature.

Phospholipids

Lipids composed of a hydrophilic head and hydrophobic tails, forming membrane bilayers; they are amphipathic.

Steroids

Lipids characterized by a four-ring carbon structure, examples include cholesterol, estrogen, and progesterone.

Membrane Bilayer

A double layer of phospholipids that forms the basic structure of cell membranes.

Amphipathic

Describes a molecule, like a phospholipid, that has both hydrophilic (water-loving) and hydrophobic (water-fearing) properties.