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Biochemistry > module 2: water > Flashcards

module 2: water Flashcards

1
Q

what is an aqueous solution

A

water based environment

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2
Q

What is an example of a water based environment and what is produced

A

cytoplasm: DNA, protein and carbohydrates

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3
Q

what is the shape of water

A

bent: 104.5 degrees

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4
Q

is water polarized or non

A

polarized

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5
Q

define electronegativity

how do scientists show

A

atoms ability to attract electron to itself within a covalent bond
Dipole arrow points to more electron negative atom

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6
Q

what are 2 other polar molecules discussed

A

glucose- OH alcohol functional group

acetic acid-carboxyl functional group

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7
Q

what does the polar nature of water permit it to dissolve

A

other polar molecules

sugar, salts,

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8
Q

what happens when water is added to an oil and what do non-polar compounds have the ability to form

A

water pushes the oil away so two layers form

non-polar compounds( oil) has ability to form plasma membranes in cells

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9
Q

Define autoionization

A

a compounds ability to react with itself to form ions

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10
Q

what is the autoionization reaction for water and what results

A

H20+H20->H30+OH
water+water->Hydronium+Hydroxide
an acid and a base
neutral pH(7)

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11
Q

Does water have a lower or higher melting and boiling point

A

higher

allows for strong intermolecular forces

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12
Q

define heat of vaporization

A

amount of heat needed to change liquid to a gas for 1 gram of substance

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13
Q

does water taste good on its own?

A

no-

has salts added to give it good taste

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14
Q

what is the average intake of water/liquids in humans

A

900mL beverage- 1050 output urine
800mL food- 100mL feces
300mL metabolic- 850 ML sweat
2000 total intake-2000 total output

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15
Q

define a non-covalent force

A

force that occur between two molecules

ex: fat soluble vitamin dissolve in cellular membrane and oil and water separate in italian dressing

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16
Q

what needs to be present for an attraction between 2 molecules

A

positive and negative charges

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17
Q

in non-covalent forces: are the charges partial or full and why

A

partial- usually partial positive or partial negative- due to difference in polarity and electronegativity

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18
Q

what are 3 types of non-covalent forces

A

dipole-dipole
hydrogen bonds
london forces

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19
Q

What is unique about dipole-dipole interaction and when do they form
give example

A

common for polar molecules
go towards higher reaction polarity
forms when 2 molecules align dipoles to create attraction
acetone and glucose: which is reason acetone is liquid
at room temperature
dipole forces in acetone are strong therefore need to be overcome for vaporization to occur

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20
Q

Where does the dipole arrow point in HCL bond

A

dipole arrow points from H to CL
indicates CL partial negative charge: but the unequal sharing of electron and is not formal charge
results in polarized molecule

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21
Q

What would the HCL bond be similar to in comparison

A

a magnet with its positive and negative charge

H+ and CL-

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22
Q

what is the strongest class of intermolecular forces

A

dipole-dipole interactions

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23
Q

What are hydrogen bonds and how to they result

A 
strongest class of dipole dipole interactions
result from negative and positive partial charges
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24
Q

what two parts must be present for a hydrogen bond to occur

A

hydrogen donor- source of partial (+)

hydrogen acceptor- source of partial (-)

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25
Q

what must a H atom be bonded to act as hydrogen donor

A

covalently bonded to O, N, F

donor portion can only be one of the above atoms bonded to H

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26
Q

What is the hydrogen acceptor

does it have to be present in a hydrogen bond

A

pair of non-bonded electron on a seperate O, N, F
serves as source of partial (-)
yes

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27
Q

Can H donors and acceptors exist on different molecules and how do they interact

A

yes

any one H donor can interact with a different acceptor

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28
Q

What are 2 examples of hydrogen bonds

what shows the hydrogen bond

A

NH3+NH3 and water and methanol

4 parallel lines

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29
Q

how many hydrogen bonds does water form when it freezes?

A

about 4

3.7 to be most accurate

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30
Q

what is the critical reason water has unique properties

such as high boiling and melting point

A

hydrogen bonding

water molecule forms multiple H bonds: many H interacting

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31
Q

which bonds are the strongest non-covalent forces

A

hydrogen

which is why water has a much higher boiling point than other molecules

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32
Q

which interaction of forces is the weakest

A

london forces

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33
Q

how are london forces characterized

A

temporary collection of interactions of molecules that form partial (+) and (-) charges

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34
Q

what forms during a london force interaction

A

dipole forms due to random electron movement and is temporary- will come and then go- which is why weakest force
encourages strongest attraction at a moment before releasing

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35
Q

why do london forces exist

A

because electron move quickly into bunched confirmation and then fall apart
do repeatedly- molecules are not polar and ability to interact with other molecules

36
Q

which bond is the strongest

A

covalent O-H: 400kcal

37
Q

what is one key difference between covalent and non-covalent bonds

A

covalent bonds are permanent= stability
non-covalent are non permanent- but rather interactions with (+) and (-) partial charges- result in attractions- but reduced stability- allows for more biological processes including drugs bind to protein to help body fight disease

38
Q

define hydrophilic and hydrophobic

A

water loving- hydrophilic

water fearing- hydrophobic

39
Q

what happens when polar or charged molecules are added to water

A

interact to form hydrogen bonds or dipole-dipole interactions

40
Q

what happens when non-covalent substance is added to water: i.e cooking oil

A

H atoms push oil away to form 2 layers- so water can maintain its strong non-covalent hydrogen bond

41
Q

define hydrophobic effect

A

collection of nonpolar regions minimizes interactions with H2O- while polar region interact with water

42
Q

what is the driving force behind the hydrophobic effect

A

spontaneous drive of water to bind itself through hydrogen bonds

43
Q

what is the cage structure water orders itself around to maximize H bonds

A

clathrate( hydrophobic portion of nonpolar regions)

44
Q

what is the physiological pH of a human cell

A

7.4

45
Q

Define equilibrium

A

achieved when rates of forward/reverse reactions are equal

46
Q

what is the equilibrium constant

A

way to describe rate to which the forward reaction occurs

aA+bB->cC+dD

47
Q

what is the molar concentration of water

A

55.5M

48
Q

what is K(w)

A

ion product of K equilibrium

1.0x10^-14

49
Q

what is the equation to find pH

A

pH=-log(H+)

50
Q

what is the pH of a lysosome

A

5

more acidic to help break down molecule

51
Q

What is a strong acid and give examples

A

dissolves in water and ionization ability

HCL, sulfuric acid

52
Q

what are strong bases and give examples

A 
dissolves in water and complete ionization ability
Sodium hydroxide(NaOH) and calcium hydroxide Ca(OH)2
53
Q

what is more common to be present in biological solutions

A

weak acid/bases

54
Q

what does weak mean in terms of ionization

A

partial ionization

dissolves in solution, then ionize to form H+ and the corresponding anion

55
Q

what is an example of a weak acid

A

acetic acid- CH3(COOH)

produces acetate ion( CH3 COO) and proton (H+)

56
Q

Looking at the ionization of acetic acid: which is the proton donor and acceptor?

A

proton donor: CH3COOH- generates H+ and donates

proton acceptor: CH3COO- in reverse reaction accepts H to recreate acetic acid

57
Q

how do we generally characterize a weak acid

A

HA-> A(-) + H(+) and it can reverse

58
Q

what is another name for the Ka constant

A

acid dissociation constant

can be used similarly to previous reactions with the regular equilibrium constant

59
Q

what does a larger value of Ka indicate

A

stronger acid and more H+ ion

60
Q

define buffer

A

aquauous system that resists change in pH with small amounts of H and OH added because of the weak acid or base has ability to react with or neutralize the added additions of acid or base

61
Q

what is a specific buffer that aids in cell maintaining pH

A

dihydrogen phosphate

62
Q

define buffering range

A

all react well within +1/- of pka range

example: acetic acid has pka of 4.82 and range is 3.82-5.82

63
Q

what is buffering capacity

A

limit to amount of acids/bases added that can be neutralized

64
Q

what is the bicarbonate buffer system

A

important in human body

set of 2 reactions that are reversible and connected

65
Q

what are the two components of the bicarbonate buffer system

A

CO2 produced by cells react with water to from weak carbonic acid
carbonic acid then reacts to form bicarbonate ion and proton
effective at pH of 7.4

66
Q

what are the physiological effects of the bicarbonate buffer system

A

in bloodstream: CO2 is transported from tissues to lung to be released
the kidneys/renal system balance the level of bicarbonate ions in the blood stream
the renal tubulars take up any excess HCO3-
therefore this system maintains proper pH in cells and extracellular fluids

67
Q

what is the reaction for the bicarbonate buffer system

A

CO2+H20->H2CO3->H+HCO3-

68
Q

what is enthalpy

A

heat content of a reaction
reflects amount and the kind of bond in system
dictated as (H)

69
Q

What is entropy

A

(S)
measurement of random/disorder of components of chemical system
increased random =high entropy
decreased random with increased order= lower entropy

70
Q

what is a general rule of thumb for the energy of aqueous solutions

A

reaction produces more product than reactant- increased entropy has occured
if reaction contain structures ordered than increase in enthalpy

71
Q

what is Gib free energy equation

A

G=H-TS

72
Q

what is the T in free energy equation

A

unit kelvin for temperature

73
Q

what do scientists typically measure when thinking about gibs free energy

A

the change in H, S, or T therefore change or delta G

hard to measure precisly

74
Q

when the change of G is negative

when the change of G is positive

A

the reaction is spontaneous

the reaction is not spontaneous and will not happen on its own-

75
Q

what are the 3 measures when considering thermal chemistry

A

Enthalpy-H-heat
Entropy-S-order
gibs free energy: G=H-TS

76
Q

what is the shape of water

A

Bent. The bond angle is 104.5 degrees

77
Q

What is autoionization and how is it important to water

A

Autoionization is the ability of a compound to react with itself to form ions. One water molecule reacts with a second molecule to form two ions: H3O+ and OH-. These ions exist in small amounts in pure water and influence the chemistry of water.

78
Q

name 3 non-covalent forces discussed in the module

A

london dispersion forces
dipole-dipole forces
hydrogen bonding forces

79
Q

What type of non-covalent interaction is known as the strongest dipole-dipole force?

A

hydrogen bonding

80
Q

How does the strength of London forces change with increasing molecular weight? Explain briefly.

A

As molecular weight increase, the strength of London forces also increase. This is due to the increased number of electrons in larger molecules. The larger number of electrons creates the potential of stronger temporary dipoles.

81
Q

What is the concentration, in M, of water as a pure liquid?

A

55.5 M

82
Q

Define Keq and Kw.

A

Keq is the equilibrium constant. Numerically, it is equal to the concentrations of equilibrium products (in M) multiplied together over the concentration of equilibrium reactants multiplied together.

Kw is called the ion product. It is, essentially, the Keq for water that is equal to 1.0 x 10-14; the formula is:

83
Q

Identify the acid, conjugate base, and proton in the following reaction.
HCOOH->H+ + HCOO-

A

HCOOH is the weak acid
H+ is the proton
HCOO- is the weak conjugate base

84
Q

A buffer system has a pKa of 8.5. What is its effective buffering range?

A

7.5-9.5

85
Q

Weak acid A has a pKa of 3.2, while weak acid B has a pKa of 5.6. Is Weak acid A or B the stronger of the two?

A

Weak acid A is stronger because a smaller pKa indicates a stronger acid.

86
Q

Ice melts at room temperature. What is the sign for LaTeX: \DeltaΔG in this reaction?

A

(-) negative. The reaction happens spontaneously.

87
Q

What is the role of ATP in helping a non-spontaneous reaction occur?

A

It provides a source of energy to assist the reaction. ATP breakdown has a significant negative ΔG value.

Biochemistry (9 decks)

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