Chemical Level (235 #2)

Question 1

solid

Answer 1

compact and have a definite shape and volume

Question 2

liquids

Answer 2

definite volume and assume the shape of their container

Question 3

gas

Answer 3

neither a definite shape nor volume

Question 4

chemical elements

Answer 4

a substance that cannot be split into a simpler substance by ordinary chemical means. Scientists now recognize 117 elements. Of these, 92 occur naturally on Earth.

Question 5

4 major elements

Answer 5

make up 96% of the body’s mass - O, C, H, N

Question 6

8 lesser elements

Answer 6

make up about 3.6% of the body’s mass - Ca, Fe, K, Ph, Mg, Na, Cl, S

Question 7

subatomic particles

Answer 7

The dense central core of an atom is its nucleus. Within the nucleus are positively charged protons () and uncharged (neutral) neutrons (). The tiny, negatively charged electrons () move about in a large space surrounding the nucleus. They do not follow a fixed path or orbit but instead form a negatively charged “cloud” that envelops the nucleus

Question 8

atomic number

Answer 8

The number of protons in the nucleus of an atom

Question 9

mass number

Answer 9

the sum of its protons and neutrons

Question 10

Isotopes

Answer 10

atoms of an element that have different numbers of neutrons and therefore different mass numbers

Question 11

half‐life

Answer 11

he time required for half of the radioactive atoms in a sample of that isotope to decay into a more stable form.

Question 12

atomic mass

Answer 12

(also called the atomic weight) of an element is the average mass of all its naturally occurring isotopes. Typically, the atomic mass of an element is close to the mass number of its most abundant isotope.

Question 13

compound

Answer 13

a substance that contains atoms of two or more different elements

Question 14

molecule

Answer 14

When two or more atoms share electrons

Question 15

free radical

Answer 15

an atom or group of atoms with an unpaired electron in the outermost shell. Having an unpaired electron makes a free radical unstable, highly reactive, and destructive to nearby molecules. Free radicals become stable by either giving up their unpaired electron to, or taking on an electron from, another molecule - may break apart important body molecules.

Question 16

antioxidants

Answer 16

substances that inactivate oxygen‐derived free radicals—is thought to slow the pace of damage caused by free radicals. Important dietary antioxidants include selenium, zinc, beta‐carotene, and vitamins C and E. Red, blue, or purple fruits and vegetables contain high levels of antioxidants.

Question 17

ionic bond

Answer 17

The force of attraction that holds together ions with opposite charges

Question 18

cation

Answer 18

positively charged ion

Question 19

anion

Answer 19

negatively charged ion

Question 20

electrolyte

Answer 20

An ionic compound that breaks apart into positive and negative ions in solution. Most ions in the body are dissolved in body fluids as electrolytes, so named because their solutions can conduct an electric current.

Question 21

covalent bond

Answer 21

two or more atoms share electrons rather than gaining or losing them - a single (─), double (═), or triple (≡) covalent bond.

Question 22

nonpolar covalent bond

Answer 22

two atoms share the electrons equally—one atom does not attract the shared electrons more strongly than the other atom

Question 23

polar covalent bond

Answer 23

the sharing of electrons between two atoms is unequal—the nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom. When polar covalent bonds form, the resulting molecule has a partial negative charge near the atom that attracts electrons more strongly. This atom has greater electronegativity, the power to attract electrons to itself. At least one other atom in the molecule then will have a partial positive charge.

Question 24

hydrogen bond

Answer 24

when a hydrogen atom with a partial positive charge (δ+) attracts the partial negative charge (δ−) of neighboring electronegative atoms, most often larger oxygen or nitrogen atoms. Thus, hydrogen bonds result from attraction of oppositely charged parts of molecules rather than from sharing of electrons as in covalent bonds, or the loss or gain of electrons as in ionic bonds. Hydrogen bonds are weak compared to ionic and covalent bonds. Thus, they cannot bind atoms into molecules. However, hydrogen bonds do establish important links between molecules or between different parts of a large molecule, such as a protein or nucleic acid

Question 25

surface tension

Answer 25

a measure of the difficulty of stretching or breaking the surface of a liquid

Question 26

chemical reaction

Answer 26

when new bonds form or old bonds break between atoms

Question 27

Energy

Answer 27

the capacity to do work

Question 28

potential energy

Answer 28

energy stored by matter due to its position

Question 29

kinetic energy

Answer 29

energy associated with matter in motion

Question 30

law of conservation of energy

Answer 30

The total amount of energy present at the beginning and end of a chemical reaction is the same. Although energy can be neither created nor destroyed, it may be converted from one form to another.

Question 31

Exergonic reactions

Answer 31

release more energy than they absorb

Question 32

endergonic reactions

Answer 32

absorb more energy than they release

Question 33

activation energy

Answer 33

The collision energy needed to break the chemical bonds of the reactants - This initial energy “investment” is needed to start a reaction. The reactants must absorb enough energy for their chemical bonds to become unstable and their valence electrons to form new combinations.

Question 34

Concentration

Answer 34

The more particles of matter present in a confined space, the greater the chance that they will collide (think of people crowding into a subway car at rush hour). The concentration of particles increases when more are added to a given space or when the pressure on the space increases, which forces the particles closer together so that they collide more often.

Question 35

Temperature

Answer 35

As temperature rises, particles of matter move about more rapidly. Thus, the higher the temperature of matter, the more forcefully particles will collide, and the greater the chance that a collision will produce a reaction.

Question 36

Catalysts

Answer 36

hemical compounds that speed up chemical reactions by lowering the activation energy needed for a reaction to occur - enzymes. A catalyst does not alter the difference in potential energy between the reactants and the products. Rather, it lowers the amount of energy needed to start the reaction

Question 37

synthesis reactions

Answer 37

When two or more atoms, ions, or molecules combine to form new and larger molecules - ANABOLISM - endergonic

Question 38

Decomposition reactions

Answer 38

split up large molecules into smaller atoms, ions, or molecules - CATABOLISM - exergonic

Question 39

exchange reactions

Answer 39

they consist of both synthesis and decomposition reactions

Question 40

reversible reaction

Answer 40

the products can revert to the original reactants. whatever is written above or below the arrows indicates the condition needed for the reaction to occur. Many reversible reactions in the body require catalysts called enzymes.

Question 41

reversible reaction

Answer 41

the products can revert to the original reactants, with the special conditions (sometime via catalysts/enzymes).

Question 42

red-ox reaction

Answer 42

reduction = the gain of electrons and the reduced substance gains energy. Oxidation - the loss of electrons and the release of energy. red-ox reactions are always parallel - when one substance is oxidized, another is reduced at the same time.

Question 43

inorganic compound

Answer 43

usually lack carbon and are structurally simple - may have only a few atoms and cannot be used for complicated biological functions. Usually made of ionic and covalent bonds, include WATER (55-60% of the body), salts, acids and bases. (other 1-2%)

Question 44

organic compound

Answer 44

always contain carbon, usually hydrogen and always covalent bonds. Most are large molecules - make up 38-43% of the body.

Question 45

solvent

Answer 45

the polarity of WATER makes it an excellent solvent.In a solution, a substance called the solvent dissolves another substance called the solute

Question 46

hydrophilic

Answer 46

solutes that are charged or contain polar covalent bonds are 'water-loving' solutes, meaning they dissolve easily in water.

Question 47

hydrophobic

Answer 47

molecules that contain non-polar covalent bonds are 'water-fearing', meaning they don't dissolve easily in water

Question 48

hydrolysis

Answer 48

decomposition reaction breaks down the large molecules into smaller ones with the addition of water. (enable nutrients to be absorbed into the body)

Question 49

dehydration synthesis reaction

Answer 49

when smaller molecules are joined together and as a result, water is one of the products. (happens during synthesis of proteins and other large molecules).

Question 50

heat capacity of water

Answer 50

water can absorb or release a relatively large amount of heat with only a modest change in its own temperature. For this reason, water is said to have a high heat capacity. This is due to the high number of hydrogen bonds in H2O

Question 51

lubricant

Answer 51

water is a major component of mucus and other lubricating fluids between organs, in joints, inside the GI tract, etc

Question 52

mixture

Answer 52

molecules that are blended together but not bound by chemical bonds

Question 53

acid

Answer 53

substance that disassociates into one or more H+ and an anion - known as a proton donor

Question 54

base

Answer 54

disassociates into an OH- and a cation - known as a proton acceptor.

Question 55

salt

Answer 55

disassociates into a cation and anion, neither of which is OH- or H+

Question 56

pH

Answer 56

solution's acidity or alkalinity, which extends from 0 to 14. Based on the molarity of H+. one level change means a tenfold difference in the H+ molarity. less than 7 is acidic, more is basic.

Question 57

buffer systems in homeostasis

Answer 57

Homeostatic mechanisms maintain the pH of blood between 7.35 and 7.45, the pH of blood falls below 7.35, a condition called acidosis occurs, and if the pH rises above 7.45, it results in a condition called alkalosis. The chemical compounds that can convert strong acids or bases into weak ones are called buffers. They do so by removing or adding protons (H+).

Question 58

carbonic acid–bicarbonate buffer system

Answer 58

Carbonic acid (H2CO3) can act as a weak acid, and the bicarbonate ion (HCO3−) can act as a weak base. Hence, this buffer system can compensate for either an excess or a shortage of H+. For example, if there is an excess of H+ (an acidic condition), HCO3− can function as a weak base and remove the excess H+. If there is a shortage of H+ (an alkaline condition), by contrast, H2CO3 can function as a weak acid and provide needed H+.

Question 59

carbohydrate

Answer 59

include sugars, glycogen, starches and cellulose. represent 2-3% of body mass. function mainly as a source of chemical energy for generating ATP needed to drive metabolic reactions. consists of C H & O. generally contain one water molecule for each carbon atom 'watered carbon'.

Question 60

monosaccharides

Answer 60

simple sugars, the monomers of carbohydrates, containing 3-7 carbon atoms. '-ose' names, like 'hexose glucose', which is broken down to produce ATP.

Question 61

disaccharide

Answer 61

molecule formed by the combo of two monosaccharides. Created by dehydration synthesis, broken by hydrolysis.

Question 62

polysaccharide

Answer 62

contains tens of hundreds of monosaccharides joined through dehydration synthesis - insoluble in water and do not taste sweet. GLYCOGEN (glucose monomers linked in branching chains). Starches, formed in plants. Can be broken down through hydrolysis Cellulose is formed by plants but cannot be digested by humans (provides bulk to eliminate feces).

Question 63

lipids

Answer 63

make up 18-25% of body mass. Fewer polar covalent bonds than carbs, so insoluble in water.

Question 64

lipoproteins

Answer 64

lipids that have joined with hydrophilic protein molecules to become more soluble in blood plasma. Proteins are on the outside, lipids are on the inside.

Question 65

fatty acids

Answer 65

used to synthesize triglycerides and phospholipids - can be catabolized to generate ATP. Consists of a carboxyl group and a hydrocarbon chain.

Question 66

saturated fatty acid

Answer 66

contains only single covalent bonds between carbon atoms of the hydrocarbon chain - each carbon atom is 'saturated' with hydrogen.

Question 67

unsaturated fatty acid

Answer 67

contains one or more double covalent bonds, has a kink at the site of the double bond. One kink = monounsaturated. more than one kink = polyunsaturated

Question 68

triglycerides

Answer 68

most plentiful lipids in body. contains a single glycerol molecule and three fatty acids. Can be either solid (fat) or liquid (oil) at room temp. the kinks in poly & monounsaturated fatty acids prevent the molecules from packing closely together and solidifying.

Question 69

phospholipids

Answer 69

glycerol backbone with two fatty acids and a phosphate group, which links a charged group usually containing N to the 'head', making it polar. Forms Hbonds with H2O. the two fatty acid 'tails' are nonpolar and only interact with other lipids. AMPHIPATHIC - has polar and nonpolar parts. So link up tail to tail in a double row to make up much of the cell membrane.

Question 70

steriods

Answer 70

contain four rings of carbon atoms. Cholesterol is used to synthesize other steriods. Others are estrogens, testosterone, cortisol, bile salts and Vit D = sterols, containing one hydroxyl (-OH) group.

Question 71

cholesterol

Answer 71

minor component of all animal cell membranes, precursor of bile salts, vit D and other steroid hormones.

Question 72

eicosanoids

Answer 72

lipids derived from a 20-carbon fatty acid called arachidonic acid.

Question 73

prostaglandin

Answer 73

eicosanoid - modify responses to hormones, contribute to the inflammatory response, prevent stomach ulcers, dilate airways to the lungs, reg body temp and influence formation of blood clots.

Question 74

leukotrienes

Answer 74

eicosanoid - participate in allergic and inflammatory responses

Question 75

proteins

Answer 75

large molecules that contain C H O and N (sometimes S). 12-18% of body mass. Structural (framework of body parts), Regulatory (hormones, neurotransmitters), Contractile (shortening of muscle fibres), Immunological (aid responses to protect body), Transport (carry vital substances around body like hemoglobin tx O2 in blood), Catalytic (enzymes to regulate biochemical rxns).

Question 76

amino acids

Answer 76

monomers of proteins. 20 in total. Each has an H with 3 functional groups attached to central C - amino group (-NH2), acidic carboxyl group (-COOH) and side chain (R group). At neutral pH, amino group and carboxyl group are ionized.

Question 77

peptide bond

Answer 77

covalent joining of each pair of amino acids. forms between C of carboxyl group and N of amino group via dehydration synthesis. Breaking is done through hydrolysis.

Question 78

peptide

Answer 78

4-9 amino acids joined in a chainlike manner

Question 79

polypeptide

Answer 79

10-2000 or more amino acids joined.

Question 80

protein structures of organization

Answer 80

primary - unique sequence to form peptide chain. secondary - repeated twisting (alpha helix) or folding (beta pleated sheets) of neighbouring amino acids in the chain. Stabilized by H bonds, form regular intervals along the polypeptide backbone. tertiary - 3D shape. quaternary - the arrangement of polypeptide chains relative to one another.

Question 81

fibrous proteins

Answer 81

insoluble in water and chains form long strands II to each other. collagen, elastin, keratin, dystrophin (structural), fibrin (blood clotting), myosin and actin (contractile).

Question 82

globular proteins

Answer 82

soluble in H2O and spherical. metabolic functions: enzymes (catalytic), antibodies and complement proteins (immunological), albumins (regulatory), membrane proteins (transport), hormones (regulatory).

Question 83

denaturation

Answer 83

when a protein encounters an altered environment, it may lose it's characteristic shape and become no longer functional. Like egg-white (albumin) applied to heat turns white and insoluble.

Question 84

enzymes

Answer 84

consist of two parts - apoenzyme (protein) and cofactor (metal ion or organic molecule called coenzyme). '-ase' names. HIGHLY SPECIFIC - bind to specific SUBSTRATES (reactant molecules on which enzyme acts) at it's ACTIVE SITE (either fits the substrate or does an 'induced fit' to fit snugly around the substrate. VERY EFFICIENT. SUBJECT TO VARIETY OF CELLULAR CONTROLS. They lower the activation energy of a rxn by decreasing the randomness of collisions, and orient substrates properly.

Question 85

nucleic acids

Answer 85

huge organic molecules that contain C H O N & P - a chain of repeating monomers called nucleotides.

Question 86

DNA - deoxyribonucleic acid

Answer 86

forms inherited genetic material inside each human cell. each GENE is a segment of the DNA molecule. Control protein synthesis and regulate most of cell activities. Contains N-base, Pentose Sugar (deoxyribose) & Phosphate Group. The Nbases are adenine (A), thymine (T), cytosine (C) and guanine (G). Deoxyribose attaches to each Nbase, alternating with Phosphate groups to form 'backbone'. DOUBLE HELIX.

Question 87

RNA - ribonucleic acid

Answer 87

single-stranded. Pentose sugar = ribose, contains uracil (U) instead of thymine. Messanger, Ribosomal and transfer are 3 types.

Question 88

Adenosine Triphosphate

Answer 88

ATP - the 'energy currency' of living systems - txs the energy liberated in exergonic catabolic rxns to power cellular activities that are endergonic (muscular contractions, movement of chromosomes during cell division, movement of structures within cells, transport of substances across cell membranes and synthesis of larger molecules from smaller ones). 3 P groups attached to adenosine and the 5C sugar ribose.

Question 89

ATPase

Answer 89

the enzyme that catalyzes the hydrolysis of ATP. (exergonic hydrolysis)

Question 90

ATP synthase

Answer 90

the enzyme that catalyzes the addition of a Pgroup to ADP (endergonic, dehydration synthesis)

Question 91

cellular respiration

Answer 91

the catabolism of glucose, supplies energy for the production of ATP. Two phases - anaerobic (series of rxns that don't require O2 - glucose is broken down by a series of catabolic rxns into pyurvic acid - each glucose makes 2 ATP. AEROBIC phase is when there is O2 and glucose is completely broken down in to CO2 and H2O, generating heat and 36 or 38 ATP.