biology exam 1

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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

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

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

Adhesion

The clinging of one substance to another

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

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

Macromolecules

Giant molecules

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

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

Monosaccharides

The simplest carbohydrates (they are the monomers for more complex carbohydrates)

Polysaccharide

A polymer of many monosaccharides

Glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction

Starch

A storage polysaccharide in plants

Glycogen

A storage polysaccharide of glucose found in animals

Cellulose

A structural polysaccharide of plant cell walls

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

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

Unsaturated fatty acid

A fatty acid that has one or more double bonds between carbons in the hydrocarbon tail

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

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

Essential Nutrients

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

Cofactors

Any nonprotein molecule or ion

Coenzymes

An organic molecule

Sickle-cell disease

A human genetic disease caused by a single amino acid substitution in the hemoglobin protein

Nucleic acids

Polymers made of monomers called nucleotides that store

Plasma Membrane

A selective barrier that allows passage of enough oxygen

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

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

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

Chloroplasts

Found in plants and algae

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

Extracellular matrix (ECM)

A matrix made up of glycoproteins such as collagen