Ap Biology Cliffs Ch2

Front 1

atom

Back 1

consists of nucleus of positively charged protons and neutrally charged neutrons

Front 2

molecule

Back 2

groups of two or more atoms held together by chemical bonds

Front 3

electronegativity

Back 3

the ability of an atom to attract electrons

Front 4

ionic bond

Back 4

form between two atoms when one or more electrons are transferred from one atom to the other- occurs when electronegativities of atoms are very different

Front 5

ions

Back 5

atoms with overall positive or negative charges

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covalent bond

Back 6

form when electrons between atoms are shared- neither atom completely retains possession of the electrons- occur when electronegativities of atoms are similar

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nonpolar covalent bond

Back 7

electrons are shared equally- electronegativities of atoms are identical

Front 8

polar covalent bond

Back 8

electrons are shared unequally- different electronegativities- unequal distribution of electrons

electrons forming bond are closer to the atom with the greater electronegativity and produce a negative charge (pole) near that atom

area around the atom with the weaker pull on the electrons produces a positive pole

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single covalent

double covalent

triple covalent

Back 9

2 electrons shared

4 electrons shared

6 electrons shared

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hydrogen bond

Back 10

weak bonds between molecules

form when a positively charges hydrogen atom in one covalently bonded molecule is attracted to a negatively charged area of another covalently bonded molecule

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solvent

solute

Back 11

solute is a substance that dissolves in a solvent

Front 12

hydrophilic

Back 12

water loving

(substances with polar covalent bonds)

Front 13

hydrophobic

Back 13

water fearing

(substances with nonpolar covalent bonds)

Front 14

aqueous solution

Back 14

solution where water is the solvent

Front 15

specific heat

Back 15

degree to which a substance changes temp in response to gain or loss of heat

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heat of fusion

Back 16

energy required to change water from solid to liquid

Front 17

heat of vaporization

Back 17

energy required to change water from liquid to gas

Front 18

properties of water

Back 18

1. water is an excellent solvent- poles of water molecules interact with substances to separate them

2. water has high specific heat capacity- changes temp very slowly with changes in heat content- when water changes state, energy is absorbed but water temp stays constant. the absorbed energy is used only to change the physical state of water by breaking hydrogen bonds

3. ice floats- water expands as it freezes (unlike most substances) in solid state, weak hydrogen bonds between water molecules become rigid and form a crystal that keeps molecules separated and less dense than liquid form

4. water has strong cohesion (attraction between like substances) and surface tension- strong cohesion occurs because of hydrogen bonding between molecules- produces high surface tension (many insects can walk upon it)

5. water has strong adhesion (attraction of unlike substances)- results from attraction of poles of water molecules to other substances- demonstrates capillary action by rising up walls of tubes

Front 19

organic molecules

Back 19

molecules that have carbon atoms

Front 20

macromolecules

Back 20

large organic molecules that may consist of hundreds or thousands of atoms

Front 21

polymers

Back 21

(most macromolecules are polymers)

molecules that consist of a single unit (monomer) repeated many times

Front 22

carbohydrates

Back 22

1.monosaccharide- simplest kind of carbohydrate- consists of a single sugar molecule

2. disaccharide- consists of two sugar molecules joined by a glycosidic linkage

3.polysaccharide- consists of a series of connected monosaccharides is a polymer(ex. starch- energy storage molecule in plants, glycogen- energy storing molecule in animals, cellulose-structural molecule for plant walls, chitin- structural molecule for wall of fungus cells and in insect exoskeletons)

Front 23

condensation reaction

Back 23

chemical reaction where a small molecule is lost in joining molecules (dehydration reaction if lost molecule is water)

Front 24

hydrolysis

Back 24

one molecule is split to form two molecules by the addition of water

Front 25

lipids

Back 25

nearly insoluble in water but highly soluble in nonpolar substances

1. triglycerides- fat and oils- consist of three fatty acids attached to glycerol molecule

2. phospholipid- like triglyceride except one fatty acid chain is replaced by a phosphate group. an additional and variable group is covalently attached to the phosphate group

the two fatty acid tails are nonpolar and hydrophobic, and the phosphate head is polar and hydrophillic

3. steroids- backbone of four linked carbon rings (ex. cholesterol-component of cell membranes, and certain hormones including estrogen and testosterone)

Front 26

saturated fatty acid

Back 26

single covalent bond between each pair of carbon atoms, and each carbon has two hydrogens bonded to it (saturated with hydrogen)

pack together more tightly, have higher melting temperatures, and usually solid at room temp (fats)

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unsaturated fatty acid

Back 27

-monounsaturated- one double covalent bond, and each of the two carbons in this bond had only one hydrogen bonded to it

-polyunsaturated- like monounsaturated except there are two or more double covalent bonds

pack together more loosely, have lower melting temperatures, and usually liquid at room temp (oils)

Front 28

proteins

Back 28

all proteins are polymers of amino acids- bonds between amino acids are peptide bonds and chain is a polypeptide (form by dehydration synthesis)

1. structural proteins- keratin in hair and horns of animals, collagen in connective tissues, and silk in spider webs

2. storage proteins- casein in milk, ovalbumin in egg whites, and zein in corn seeds

3. transport proteins- such as those in membranes of cells that transport materials into and out of cells and as oxygen-carrying hemoglobin in red blood cells

4. defensive proteins- such as antibodies that provide protection against foreign substances that enter bodies of animals

5. enzymes- regulate the rate of chemical reactions

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primary structure of a protein

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describes the order of amino acids

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secondary structure of a protein

Back 30

a three-dimensional shape that results from hydrogen bonding between amino and carboxyl groups of adjacent amino acids. bonding produces a spiral (alpa helix) or folded place (beta pleated sheet). Proteins whose shapes are dominated by these two patterns often form fibrous proteins

Front 31

tertiary structure of a protein

Back 31

additional three-dimensional shaping and often dominate the structure of globular proteins

-hydrogen bonding between r groups of amino acids

-ionic bonding between r groups of amino acids

-hydrophobic effect that occurs when hydrophobic r groups move towards center of the protein

-formation of disulfide bonds that occurs when sulfur atom in amino acid cysteine bonds to sulfur atom in another cysteine- this disulfide bridge helps maintain folds in the amino acid chain

Front 32

quaternary structure

Back 32

describes a protein that is assembled from two or more separate peptide chains (two or more subunits)

(ex hemoglobin- consists of four peptide chains held together by hydrogen bonding and interactions among r groups)

Front 33

Nucleic acids

Back 33

DNA & RNA

genetic information of a cell is stored in molecules of DNA and DNA, in turn, passes its genetic instructions to RNA for directing varios metabolic activities of the cell

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DNA

Back 34

double helix

polymer of nucleotides- consists of nitrogen base, five carbon sugar called deoxyribose, and a phosphate group

four nucleotides, each with one of four nitrogen bases:

1. adenine- double ring base (purine)

2. thymine- single ring base (pyrimidine)

3. cytosine- single ring base (pyrimidine)

4. guanine- double ring base (purine)

two strand of DNA helix are antiparallel, oriented in opposite directions. One strand arranged in 5' to 3' direction and adjacent strand oriented the opposite

Front 35

RNA

Back 35

sugar in nucleotides is ribose

thymine nucleotide does not occur- replaced by uracil (binds with adenine)

usually single- stranded and does not form double helix

Front 36

activation energy

Back 36

sufficient energy in chemical reactions that triggers formation of new bonds

Front 37

catalyst

Back 37

accelerates rate of reaction by lowering activation energy without being used up itself

Front 38

metabolism

Back 38

chemical reactions that occur in biological systems

includes breakdown of substances (catabolism), formation of new substances (synthesis or anabolism), or the transferring of energy from one substance to another

Front 39

chemical equilibrium

Back 39

the rate of reaction in the forward direction equals the rate in the reverse direction (and, as a result, there is not net production of reactants or products)

Front 40

enzymes

Back 40

globular proteins that act as catalysts for metabolic reactions

-substrate is the substance upon which the enzyme acts

-enzymes are substrate specific

-an enzyme is unchanged as a result of the reaction

-an enzyme catalyzes a reaction in both forward and reverse reactions

-the efficiency of an enzyme id affected by temp and pH

-the induced fit model describes how enzymes work

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denatured

Back 41

when proteins lose their three dimensional shape as hydrogen bonds and peptide bonds break down- enzymes lose their ability to catalyze reactions (usually occurs when placed in very high temps)

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cofactors

Back 42

nonprotein molecules that assist enzymes

-coenzymes - organic cofactors

-inorganic cofactors - often metal ions

Front 43

ATP

Back 43

common source of activation energy for metabolic reactions. When ATP releases its energy, a hydrolysis reaction breaks the last phosphate bond of the ATP molecule to form ADP. In reverse direction, new ATP molecules are assembles by phosphorylation when ADP combines with a phosphate group using energy obtained from some energy rich molecule

Front 44

enzyme binding sites

Back 44

one active site for the substrate and more or more possible allosteric sites for an allosteric effector

Front 45

allosteric effectors

Back 45

allosteric activator- binds to the enzyme and induces the enzymes active form

allosteric inhibitor- binds to the enzyme and induces the enzymes inactive form

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feedback inhibition

Back 46

an end product of a series of reactions acts as an allosteric inhibitor, shutting down one of the enzymes catalyzing the reaction series

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competitive inhibition

Back 47

a substance that mimics the substrate inhibits and enzyme by occupying the active site. The mimic displaces the substrate and prevents the enzyme from catalyzing the substrate

Front 48

noncompetitive inhibition

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a substance inhibits the action of an enzyme by binding to the enzyme at a location other than the active site (allosteric site). Inhibitor changes the shape of the enzyme which disables its enzymatic activity

Front 49

cooperativity

Back 49

an enzyme becomes more receptive to additional substrate molecules after one substrate molecule attaches to an active site.