bio exam 1

Matter

Anything that takes up space and has mass.

Element

A substance that cannot be broken down to other substances by chemical reactions.

Compound

A substance consisting of two or more different elements in a fixed ratio.

Trace elements

Elements required by an organism in only minute quantities but are still essential for life.

Isotope

An atomic form of an element with the same number of protons but a different number of neutrons.

Radioactive decay

A process where the nuclei of unstable isotopes spontaneously give off particles and energy.

Valence shell

The outermost electron shell of an atom, which is involved in forming chemical bonds.

Ionic Bonding

A chemical bond resulting from the attraction between oppositely charged ions after the complete transfer of one or more electrons from one atom to another.

Covalent bond

A strong chemical bond in which two atoms share one or more pairs of valence electrons.

Molecule

Two or more atoms held together by covalent bonds.

Electronegativity

The measure of the attraction of a particular atom for the electrons in a covalent bond.

Reactants

The starting materials in a chemical reaction.

Products

The materials resulting from a chemical reaction.

Reversible (reaction)

A chemical reaction in which the products can react to re-form the reactants.

Chemical equilibrium

The state in a reversible reaction where the rate of the forward reaction equals the rate of the reverse reaction.

Polarity

A property of a molecule with an uneven distribution of charge, resulting in partially positive and partially negative regions.

Hydrogen bond

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

Cohesion

The sticking together of like molecules, such as water molecules being attracted to each other.

Adhesion

The clinging of one substance to another, such as water molecules sticking to a polar surface.

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid.

Kinetic energy

The energy of motion.

Heat

A measure of the total amount of kinetic energy due to molecular motion in a body of matter.

Temperature

A measure of the average kinetic energy of the molecules in a body of matter.

Specific heat

The amount of heat that must be absorbed or lost for 1 gram of a substance to change its temperature by 1°C.

Solvent

The dissolving agent of a solution.

Solute

A substance that is dissolved in a solution.

Aqueous solution

A solution in which water is the solvent.

Hydrophilic

Having an affinity for water; "water-loving." These substances are typically polar or ionic.

Hydrophobic

Having no affinity for water; "water-fearing." These substances are typically nonpolar.

Hydronium ion (H3O +)

A water molecule with an extra proton attached; often simplified as H+.

Hydroxide ion (OH⁻)

A water molecule that has lost a proton, resulting in a negative charge.

Acid

A substance that increases the hydrogen ion (H+) concentration of a solution.

Base

A substance that reduces the hydrogen ion (H+) concentration of a solution.

pH

A measure of hydrogen ion concentration on a logarithmic scale; a lower pH is more acidic, a higher pH is more basic.

Buffers

Substances that minimize changes in the concentrations of H+ and OH− in a solution, thereby resisting changes in pH.

Macromolecules

Giant molecules, such as proteins or nucleic acids, formed by the joining of smaller molecules (monomers).

Polymers

Long molecules consisting of many similar or identical building blocks (monomers) linked by covalent bonds.

Monomers

The repeating building blocks of a polymer.

Enzymes

Macromolecules, typically proteins, that act as catalysts to speed up chemical reactions without being consumed.

Dehydration reaction

A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule.

Hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water.

Carbohydrates

A class of macromolecules that includes sugars and their polymers, used for energy and structure.

Monosaccharides

The simplest carbohydrates, or simple sugars; they are the monomers for more complex carbohydrates.

Polysaccharide

A polymer of many monosaccharides, formed by dehydration reactions.

Glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

Starch

A storage polysaccharide in plants, consisting of glucose monomers.

Glycogen

A storage polysaccharide of glucose found in animals.

Cellulose

A structural polysaccharide of plant cell walls, consisting of glucose monomers.

Chitin

A structural polysaccharide found in the exoskeleton of arthropods and the cell walls of fungi.

Lipids

A diverse group of hydrophobic molecules that includes fats, phospholipids, and steroids.

Fats (Triglycerides)

Lipids consisting of three fatty acids linked to one glycerol molecule; used for long-term energy storage.

Phospholipids

Lipids made up of glycerol joined to two fatty acids and a phosphate group; they form the lipid bilayers of cell membranes.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings.

Fatty acid

A long carboxylic acid chain; the tails of fat molecules.

Saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, resulting in a straight chain.

Unsaturated fatty acid

A fatty acid that has one or more double bonds between carbons in the hydrocarbon tail, resulting in a "kinked" or bent chain.

Proteins

A biologically functional molecule consisting of one or more polypeptides folded into a specific three-dimensional structure.

Polypeptides

Polymers of amino acids linked together by peptide bonds.

Amino acids

Organic molecules possessing both a carboxyl and an amino group; they serve as the monomers of polypeptides.

Peptide bond

The covalent bond between the carboxyl group of one amino acid and the amino group of another, formed by a dehydration reaction.

Primary structure

The specific linear sequence of amino acids in a polypeptide chain.

Secondary structure

Regions of repetitive coiling (alpha helix) or folding (beta pleated sheet) of the polypeptide backbone of a protein due to hydrogen bonding.

Tertiary structure

The overall 3D shape of a polypeptide resulting from interactions between the R groups (side chains) of the amino acids.

Quaternary structure

The overall protein structure that results from the aggregation of two or more polypeptide subunits.

Denaturation

A process in which a protein loses its native shape due to environmental factors, thereby becoming biologically inactive.

Essential Nutrients

Nutrients that an organism cannot synthesize on its own and must obtain from its diet.

Cofactors

Any nonprotein molecule or ion, often an inorganic mineral, that is required for the proper functioning of a protein.

Coenzymes

An organic molecule, such as a vitamin, serving as a cofactor.

Sickle-cell disease

A human genetic disease caused by a single amino acid substitution in the hemoglobin protein, which alters its structure and function.

Nucleic acids

Polymers made of monomers called nucleotides that store, transmit, and help express hereditary information.

Plasma Membrane

A selective barrier that allows passage of enough oxygen, nutrients, and waste to service the entire cell.

Prokaryotic cells

Cells characterized by having no nucleus and no membrane-bound organelles.

Eukaryotic cells

Cells characterized by having DNA in a nucleus that is bounded by a membranous nuclear envelope and having membrane-bound organelles.

Cytosol

The semifluid, jellylike substance in which subcellular components are suspended.

Cytoplasm

The interior of either type of cell; in eukaryotes, it is the region between the nucleus and the plasma membrane.

Nucleus

Contains most of the cell's genes and is usually the most conspicuous organelle.

Ribosomes

Complexes made of ribosomal RNA and protein that carry out protein synthesis.

Endomembrane system

A system of membranes in eukaryotic cells that regulates protein traffic and performs metabolic functions.

Vesicles

Sacs made of membrane used for transport.

Endoplasmic Reticulum (ER)

An extensive network of membranes that is continuous with the nuclear envelope.

Golgi apparatus

An organelle consisting of stacks of flat membranous sacs that modify, store, and route products of the ER.

Lysosome

A membranous sac of hydrolytic enzymes that can digest macromolecules.

Vacuoles

Large vesicles derived from the endoplasmic reticulum and Golgi apparatus.

Mitochondria

The sites of cellular respiration, a metabolic process that uses oxygen to generate ATP.

Chloroplasts

Found in plants and algae, are the sites of photosynthesis.

Cytoskeleton

A network of fibers extending throughout the cytoplasm that organizes the cell’s structures and activities.

Cell wall

An extracellular structure that distinguishes plant cells from animal cells, providing protection and support.

Extracellular matrix (ECM)

A matrix made up of glycoproteins such as collagen, proteoglycans, and fibronectin that animal cells are covered by.