Chapter 1 and 2 Human Bio

Flashcards covering atomic structure, chemical bonding, water properties, pH, and the four classes of biological macromolecules.

Matter

Anything that has mass and takes up space.

Atom

The smallest unit of matter that retains the properties of an element, composed of protons, neutrons, and electrons.

Atomic number

The number of protons in the nucleus of an atom, which determines the identity of the element.

Atomic mass

The total mass of an atom, typically measured as the sum of protons and neutrons in the nucleus.

Nucleus

The central part of an atom where protons and neutrons reside.

Proton

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

Neutron

A subatomic particle with no charge (neutral) found within the atomic nucleus.

Electron

A subatomic particle with a negative charge that resides in shells or orbitals surrounding the nucleus.

Electron shell

An energy level at a specific distance from the nucleus where electrons are found; the first shell holds $2$ and subsequent shells can hold up to $8$.

Isotopes

Atoms of the same element that have the same number of protons but differ in the number of neutrons.

Radioactivity

The process by which certain unstable isotopes, known as radioisotopes, break down and emit radiation.

Electronegativity

A measure of an atom's attraction for shared electrons in a chemical bond.

CHNOPS

An acronym for Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur, which are the predominant elements in all cells.

Orbital

A specific region within an electron shell where an electron is most likely to be located.

Valence

The sharing capacity of an atom, determined by the number of electrons in its outermost shell.

Ionic bond

A chemical bond formed by the attraction between oppositely charged ions which form after the transfer of electrons.

Ion

An atom or molecule that has gained or lost one or more electrons, resulting in a positive or negative charge.

Electrolyte

A substance that dissociates into ions when dissolved in a solvent like water.

Covalent bond

A type of strong chemical bond where two atoms share one or more pairs of valence electrons.

Single bond

A covalent bond involving the sharing of one pair of electrons.

Double bond

A covalent bond involving the sharing of two pairs of electrons.

Polar covalent bond

A bond where electrons are shared unequally between atoms, resulting in a molecule with partial positive and negative charges.

Hydrogen bond

A weak attraction between the partially positive hydrogen atom of one polar molecule and the partially negative atom of another.

Hydrophilic

Molecules that are attracted to water and can dissolve in it; they are typically polar.

Hydrophobic

Molecules that repel water and do not mix well, such as non-polar lipids.

Solvent

The dissolving agent of a solution; water is known as the universal solvent due to its polarity.

Solute

The substance that is being dissolved in a solution.

pH scale

A logarithmic scale measuring hydrogen ion concentration; a shift of one unit represents a $10\times$ difference in concentration.

Acid

A substance that increases the hydrogen ion ($H^+$) concentration in a solution, resulting in a pH less than $7$.

Base

A substance that increases the concentration of hydroxide ions ($OH^-$) or decreases hydrogen ions, resulting in a pH greater than $7$.

Organic molecules

Molecules that are based on carbon and are typically produced by living systems.

Isomer

Molecules that have the same chemical formula but different structural arrangements, such as glucose and fructose.

Monomer

The small, basic building block molecules that link together to form larger macromolecules.

Macromolecule

Large polymers including carbohydrates, lipids, proteins, and nucleic acids.

Condensation (dehydration) synthesis

A reaction that covalently bonds monomers together to form a polymer while producing a water molecule.

Hydrolysis

A chemical reaction that breaks the bonds in a polymer by adding a water molecule.

Monosaccharide

The simplest form of carbohydrate and the monomer used to build complex sugars.

Polysaccharide

A carbohydrate polymer like starch (formed by plants), glycogen (formed by animals), or cellulose.

Saturated fat

A lipid with no double bonds in its fatty acid chains, typically solid at room temperature.

Unsaturated lipids

Lipids containing one or more double bonds in their fatty acid chains, typically liquid at room temperature.

Phospholipid

A lipid molecule with a hydrophilic head and hydrophobic tail, essential for the structure of cell membranes.

Catalyst

A substance that speeds up the rate of a chemical reaction; enzymes are proteins that act as biological catalysts.

Peptide bond

The specific type of covalent bond that links amino acids together in a protein.

Primary structure

The unique, linear sequence of amino acids in a protein.

Secondary structure

The initial folding or coiling of a polypeptide chain, such as alpha helices or beta-pleated sheets.

Tertiary structure

The overall three-dimensional shape of a single protein molecule.

Quaternary structure

The structure resulting from the grouping or interaction of two or more polypeptide chains.

Nucleic acids

Polymers like DNA and RNA that serve as the blueprint for life and carry genetic information.

Mutation

A change in the nitrogenous base sequence of DNA, which is a key driver of evolution.