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Biochemistry > Chapter 2-Water: The Solvent for Biochemical Reactions > Flashcards

Chapter 2-Water: The Solvent for Biochemical Reactions Flashcards

1
Q

What is the principal component of most cells?

A

water

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2
Q

electronegativity

A

the tendency of an atom to attract electrons to itself (so it becomes more negative) in a chemical bond

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3
Q

atoms of the same element have the same electronegativity. why?

A

because they share electrons equally in a bond

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4
Q

Which pair is more electronegative? Oxygen and Nitrogen or Carbon and Hydrogen

A

Oxygen and Nitrogen

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5
Q

If atoms of differing electronegativity form a bond, are the electrons shared equally?

A

No. More negative charge will be found closer to one of the atoms.

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6
Q

Example: In an O-H bond, where are more the electrons located?

A

near the oxygen because it is more electronegative

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7
Q

difference in electronegativity between hydrogen oxygen and hydrogen in an O-H bond gives rise to…

A

a partial positive and negative charge (S+/S-)

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8
Q

Polar Bonds

A

bonds in which two atoms have an unequal share in bonding electrons, so you notice a partial positive and negative charge

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9
Q

Non polar bonds

A

bonds where two atoms share electrons equally

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10
Q

give an example of a non-polar bond

A

C-H bond in CH4 (methane)

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11
Q

Can a bond within a molecule be polar and the molecular itself be non polar?

A

Yes. It all depends on the geometry. For example, carbon dioxide fits this criteria because of the linear nature of the O=C=O.

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12
Q

What is the geometry of water?

A

bent with a bond angle of 104.3

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13
Q

Dipoles

A

bonds with positive and negative ends due to an uneven distribution of electrons in bonds

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14
Q

Is water polar or non polar?

A

polar

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15
Q

Do polar molecules dissolve in polar compounds?

A

Yes. “Like dissolves like”

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16
Q

what are the strongest type of bonds?

A

ionic and covalent

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17
Q

does water have a large dipole moment?

A

yes. think: charge distribution

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18
Q

salt bridges

A

an interaction that depends on the attraction of unlike charges results from attraction of two side chains that are oppositely charged and in close proximity to eachother

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19
Q

ion-dipole and dipole-dipole interactions both help…

A

ionic and polar compounds dissolve in water

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20
Q

ion-dipole interactions

A

ions interacting with molecules that have dipoles example: Cl- & H20

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21
Q

van der waals forces

A

noncovalent associations based on the WEAK attraction of transient dipoles for one another

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22
Q

how many noncovalent bonds that do not involve electrostatic interaction of a fully charged ion are in van der waals forces?

A

3

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23
Q

Dipole-dipole interactions

A

occur between molecules that are dipoles, with the partial positive side attracting the partial negative side

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24
Q

dipole induced dipole interactions occur by…

A

distorting electron cloud

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25
Q

london dispersion force

A

an attraction between transient induced dipoles

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26
Q

hydrophilic

A

water loving

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27
Q

what kind of substances tend to dissolve in water?

A

ionic and polar

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28
Q

are hydrocarbons polar or non polar?

A

nonpolar

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29
Q

examples of hydrophilic substances

A

polar compounds (alcohols and ketones) sugars ionic compounds (KCl) amino acids phosphate esters

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30
Q

examples of hydrophobic substances

A

nonpolar covalent compounds (hydrocarbons) fatty acids cholesterol

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31
Q

hydrophobic

A

water-hating does not dissolve in water

32
Q

why do oil and water mixed together separate into layers?

A

has both hydrophobic (oil) and hydrophilic (water) properities

33
Q

amphipathic

A

molecule that contains an end with a polar, water-soluble group and another end with a non-polar, hydrocarbon group that is insoluble in water (aka hydrophilic and hydrophobic)

34
Q

hydrogen bonds

A

noncovalent association formed between a hydrogen atom covalently bonded to one electronegative atom and a lone pair of electrons on another electronegative atom

35
Q

hydrogen bonding occurs when hydrogen is bonded to

A

nitrogen, flourine or oxygen (FON)

36
Q

does ice or liquid water have a lower density

A

ice

37
Q

what types of bonds help stabilize DNA, RNA and proteins

A

hydrogen

38
Q

acid

A

proton (H+) donor

39
Q

base

A

proton (H+) acceptor

40
Q

acid strength

A

the tendency of an acid to dissociate to a hydrogen ion and its conjugate base (H+ and A-); amount of hydrogen ion released when a given amount of acid is dissolved in water

41
Q

acid dissociation constant

A

represented by Ka the number that characterizes the strength of an acid

42
Q

Equation for Ka

A

Ka= [H+][A-} ______ [HA]

43
Q

greater the Ka the ______ acid

A

stronger the acid

44
Q

ion product constant for water

A

represents by Kw a measure of the tendency of water to dissociate to give hydrogen ion and hydroxide ion

45
Q

equation for pH

A

pH= -log10[H+]

46
Q

what is a neutral pH

A

7

47
Q

what value is considered to be an acidic pH

A

lower than 7

48
Q

what value is considered to be an basic pH

A

higher than 7

49
Q

pKa

A

measures acid strength pka= -log10(Ka)

50
Q

the smaller the pka

A

the stronger the acid

51
Q

Henderson-Hasselbalch equation (HH eqn)

A

mathematical relationship between the pka of an acid and the pH of a solution containing the acid and its conjugate base

52
Q

HH eqn formula

A

pH= pka + log [A-]/[HA]

53
Q

titration

A

an experiment in which a measured amount of base is added to an acid

54
Q

equivalence point

A

the point in a titration where an acid is equally neutralized

55
Q

pepsin

A

found in stomach maximum activity at low pH

56
Q

lysozyme

A

maximum activity at pH of 5

57
Q

trypsin

A

most active at pH of 5

58
Q

monoprotic acids release _____ hydrogen ion and have _____ ka and ____ pka

A

1; 1; 1

59
Q

diprotic acids release _____ hydrogen ion and have _____ ka and ____ pka

A

2; 2; 2

60
Q

polyprotic acids release _____ hydrogen ion and have _____ ka and ____ pka

A

more than 2; more than 2; more than 2

61
Q

If pH of a solution is less than the pKa, what form dominates? Meaning… pH

A

protonated (H+ on)

62
Q

If pH of a solution is greater than the pKa, what form dominates? Meaning… pH>pKa

A

deprotonated (H+ off)

63
Q

buffer

A

something that resists change

64
Q

buffer solution

A

-tends to resist change in Ph on addition of moderate amounts of strong acid or strong base -consists of a mixture of a weak acid and its CB

65
Q

Le Chatelier’s Principle

A

if stress is applied to a system in equilibrium the equilibrium will shift in the direction that relieves the stress

66
Q

when the pH is higher than the pKa, the ratio of the conjugate base to form the conjugate acid form is

A

10

67
Q

when the pH is higher than the pKa, the ratio is

A

100 (see table 2.7 on page 52)

68
Q

why can a buffer maintain the pH at a relatively constant value?

A

because of the amounts of both acid and the CB (usually met at pH values at or near pKa of the acid)

69
Q

https://www.youtube.com/watch?v=UnzycyqM0G4

explain the concepts.

A
  • A- is unprotonated form (above 7)
  • HA is protonated form (below 7)
  • +/- 1 away 90:10 ratio
  • +/- 2 away 99:1 ratio
70
Q

buffering capactity

A

a measure of the amount of acid or base that can be absorbed by a given buffer solution

71
Q

how do we make a buffer?

A

add acid or base to a solution

72
Q

hemoglobin

A

oxygen carrying protein in the blood

73
Q

zwitterions

A

molecules that have both a positive and negative charge

74
Q

are zwitterions more or less likely to interfere with biochemical reactions?

A

less

75
Q

acidosis

A

blood pH drops below 7.35

76
Q

alkalosis

A

blood pH rises about 7.45

77
Q

naturally occuring phsophate and carbonate buffers help maintain physiological pH near

A

7

Biochemistry (7 decks)

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