Evolution

change in the frequency of traits in a population

Natural Selection

 
cause of the change

Adaptation

i

ncrease in fitness of population to its environment

Heritable Variations

 trait which is capable of being inherited and selected

DNA 

the genetic material that organisms inherit from their parents; a double-stranded helical macrmolecule consisting of nucleotide monomers with deoxyribose sugar and and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T)

Tropics

latitudes between 23.5° north and south

Temperature Zones 

Latitudes between the tropics and the Arctic Circle in the north and the Atlantic Circle in the south; regions with milder climates than the tropics or polar regions 

Prevailing Winds

Winds that result from the combined effects of Earth's rotation and the rising and falling of air masses 

Biome

community of species that has adapted to a paticular region

Element 

A substance that cannot be broken down to other substances by chemical means. Scientists recognize 92 occurring in nature.

Compound 

A substance containing two or more elements in a fixed ratio; for example, NaCl (table salt)

Atom

smallest particle of an element

Molecule

particle in a compound

Proton

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

Neutron

an electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom

 Electron

A subatomic partilce with a single negative electrical charge. One or more move around the nucleus of an atom. 

Nucleus

An atom's central core, containing protons and neutrons. 

Isotopes

atoms of the same element that have different numbers of neutrons; some are radioactive

Isomers

 Organic compounds with the same molecular formula but different structures and, therefore, different properties

Ion

An atom or molecule that has gained or lost one or more electrons, thus acquiring an electrical charge. 

Orbital

"cloud" occupied by an electron; shaped like a sphere or dumbbell  

Ionic Bond 

An attraction between two ions with opposite electrical charges. The electrical attraction of the opposite charges holds the ions together.

Covalent Bond

An attraction between atoms that share one or more pairs of outer-shell electrons; symbolized by single line between the atoms 

Hydrogen Bond

 A type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule (or in another part of the same macromolecule).

Polar Covalent Bond

 An attraction between atoms that share electrons unequally because the atoms differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it partially negative and the other atom partially positive.

Nonpolar Covalent Bond

An attraction between atoms that share one or more pairs of electrons equally because the atoms have similar electronegativity.

Organic Compound

A chemical compound containing the element carbon and usually synthesized by cells.

Hydrocarbon

A chemical compound composed only of the elements carbon and hydrogen 

Hydrophilic

"Water-loving"; pertaining to polar, or charged, molecules (or parts of molecules) that are soluble in water.

Hydrophobic

"Water-fearing"; pertaining to nonpolar molecules (or parts of molecules) that do not dissolve in water. 

Functional Group

An assemblage of atoms that forms the chemically reactive part of an organic molecule.

Hydroxyl Group

In an organic molecule, a functional group consisting of a hydrogen atom bonded to an oxygen atom.

Carbonyl Group

In an organic molecule, a functional group consisting of a carbon atom linked by a double bond to an oxygen atom.

Carboxyl Group

In an organic molecule, a functional group consisting of an oxygen atom double-bonded to a carbon atom that is also bonded to a hydroxyl group.

Amino Group

In an organic molecule, a functional group consisting of a nitrogen atom bonded to two hydrogen atoms.

Phosphate Group

A functional group consisting of a phosphorus atom covalently bonded to four oxygen atoms.

Macromolecule

A giant molecule in a living organism: a protein, carbohydrate, lipid or nucleic acid. 

Polymer

A large molecule consisting of many identical or similar molecular units, called monomers, covalently joined together in a chain. 

Monomer

A chemical subunit that serves as a building block of a polymer. 

Dehydration

 A chemical process in which a polymer forms as monomers are linked by the removal of water molecules. One molecule of water is removed for each pair of monomers linked.

Hydrolysis

A chemical process in which macromolecules are broken down by the chemical addition of water molecules to the bonds linking their monomers; an essential part of digestion.

Carbohydrate

 Member of the class of biological molecules consisting of simple single-monomer sugars (monosaccharides), two-monomer sugars (disaccharides), and other multi-unit sugars (polysaccharides).

Function: structures and stores energy 

Lipid

An organic compound consisting mainly of carbon and hydrogen atoms linked by nonpolar convalent bonds, making the compound mostly hydrophobic. Include fat, waxes, phospholipids, and steroids and are insoluble in water.

Function: Structures and stores energy 

Protein

A biological polymer constructed from amino acid monomers.

Function: Structures include enzymes 

Nucleic Acid

A polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular structures and activities. The two types are DNA and RNA.

Function: stores information 

Monosaccharide

The smallest kind of sugar molecule; a single-unit sugar; the building blocks of more complez sugars and polysaccharides

Disaccharide

 A sugar molecule consisting of two monosaccharides linked by a dehydration reaction. 

Polysaccharide

A carbohydrate polymer consisting of hundreds to thousands of monosaccharides (sugars) linked by covalent bonds. 

Triglyceride

 A fat, which consists of a molecule of glycerol linked to three molecules of fatty acid.

Amino Acid

An organic molecule containing a carboxyl group and an amino group; serves as the monomer of proteins.

Saturated

Pertaining to fats and fatty acids whose hydrocarbon chains contain the maximum number of hydrogens and therefore have no double covalent bonds; solidify at room temperature 

Unsaturated

Pertaining to fats and fatty acids whose hydrocarbon chains lack the maximum number of hydrogen atoms and therefore have one or more double covalent bonds; do not solidify at room temperature 

Fat

A large lipid molecule made from an alcohol called glycerol and three fatty acids; a trigylceride; most function as energy-storage molecules 

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophoic tail. 

Wax

A type of lipid molecule consisting of one fatty acid linked to an alcohol; functions as a waterproof coating on many biological surfaces, such as appples and other fruits.  

Steroid

 A type of lipid whose carbon skeleton is in the form of four fused rings: three 6-sided rings and one 5-sided ring; examples are cholestera, testosterone, and estrogen.

Enzyme

A protein that serves as a biological catalyst, changing the rate of a chemical reaction without itself being changed into a different molecule in the process. 

Peptide Bond

The covalent linkage between two amino acid units in a polypeptide; formed by a dehydration reacton  

Polypeptide

A chain of amino acids linked by peptide bonds. 

Nucleotide

An organic monomer consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group; building blocks of nucleic acids. 

 Alpha Helix

The spiral shape resulting from the coiling of a polypeptide in a protein's secondary structure 

Pleated Sheet

The folded arragnement of a polypeptide in a protein's secondary structure. 

Random Coil

disordered portion of a protein 

Prokaryotic Cell

A type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea 

Eukaryotic Cell

A type of cell that has a membrane-enclosed nucleus and other membrane-enclosed organelles; includes all organisms except bacteria and archaea 

Cell

A basic unit of living matter separated from its environment by a plasma membrane; the fundamental structural unit of life. 

Organelle

A structure with a specialized function within a cell 

Fluid Mosaic

A description of membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid molecules

Endocytosis

The movement of materials into the cytoplasm of a cell via membranous vesicles or vascuoles 

Exocytosis 

The movement of materials out of the cytoplasm of a cell via membranous vesicles or vacuoles. 

Phagocytosis

Cellular "eating"; a type of endocytosis whereby a cell engulfs macromolecules, other cells, or particles into its cytoplasm

Pinocytosis

Cellular "drinking"; a type of endocytosis in which the cell takes fluid and dissolved solutes into small membranous vesicles

Cell Nucleus

The genetic control center of eukaryotic cell 

Nucleolus

A structure within the nucleus of a eukaryotic cell where ribosomal RNA is made and assembled with proteins to make ribosomal subunits; consists of parts of the chromatin DNA, RNA transcribed from the DNA and proteins imported from the cytoplasm 

Cytoplasm

Everything inside a cell between the plasma membrane and the nucleus; consits of a semifluid medium and organelles 

Plasma Membrane

The thin layer of lipids and proteins that sets a cell off from its surroundings and acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer in which are embedded molecules of protein and cholesteral  

Cell Wall

A protective layer exernal to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape 

Chloroplast

An organelle found in plants and photosynthetic protists. Enclosed by two concentric membranes, a chloroplast absorbs sunlight and uses it to power the snthesis of organic food molecules (sugars). 

Central Vacuole

A membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, and development. 

Cytoskeleton

A meshwork of fine fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules 

Endoplasmic Reticulum

An extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions 

Rough ER

A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; studded with ribosomes that make membrane proteins and secretory proteins; constructs membrane from phospholipids are proteins 

Smooth ER

 A network of interconnected membranous tubules in a eukaryotic cell's cytoplasm; lacks ribosome; enzymes embedded in it function in the synthesis of certain kinds of molecules

Golgi Complex

an organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum 

Mitochondrion

An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two concentric membranes, it is where most of the cell's ATP is made 

Microfilaments

the thinnest of the three main kinds of protein fibers making up the cytoskelton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin. 

Microtubule

the thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a straight hollow tube made of globular proteins called tubulins; form the basis of the structure and movement of cilia and flagella 

Intermediate Filament

an intermediate-sized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells; ropelike, made of fibrous proteins 

Potential Energy

stored energy; the capacity to perform work that matter possesses because of its location or arrangement. Water behind a dam and chemical bonds possess it 

Kinetic Energy

the energy of motion; the energy of a mass of matter that is moving; moving matter performs work by transferring its motion to other matter, such as leg muscles pushing bicycle pedals 

Entropy

a measure of disorder; one form of disorder is heat, which is random molecular motion 

Reactant

(subsrate) 

 a starting material in a chemical reaction

Product

an ending material in a chemical reaction 

Exergonic Reaction

an energy-releasing chemical reaction in which the reactants contain more potential energy than the products; the reaction releases an amount of energy equal to the difference in potential energy between the reactants and the products 

Endergonic Reaction

 An energy-requiring chemical reaction, which yields prodcuts with more potential energy than the reactants; the amount of energy stored in the products equals the difference between the potential energy in the reactants and that in the products

ATP

Adenosine triphosphate, the main energy source for cells

Transistion State

The mid-stage of a reaction when bonds in the reactants are stretched

Active Site

The part of an enzyme molecule where a substrate molecule attaches (by means of weak chemical bonds); typically, a pocket or groove on the enzyme's surface

Enzyme

A protein that serves as a biological catalyst, changing the rate of a chemical reaction without itself being changed into a different molecule in the process

Cofactor
(coenzyme)

An organic molecule (usually a vitamin or a compound synthesized from a vitamin) that acts as a cofactor, helping n enzyme catalyze a metabolic reaction

Metabolic Pathway

Glycosis

A series of electron carrier molecules that shuttle electrons during the redox reactions that release energy used to make ATP; located in the inner membrane of mitchondria, the thylakoid membranes of chloroplasts, and the plasma membranes of prokaryotes

Feedback Inhibition

A method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway, thereby blocking the metabolic reaction

Lactic Acid Fermentation

the conversion of pyruvate to latate with no release of carbon dioxide

Mitotic Phase

(M Phase)

Haploid Cell