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Biochemistry > Chapter 2: Water > Flashcards

Chapter 2: Water Flashcards

1
Q

____________ gives water its unusual properties

A

Hydrogen bonds

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2
Q

What is the dissociation energy for hydrogen bonds

A

23Kj/mol

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3
Q

______________ are responsible for water high melting point due to the thermal energy need to break the bonds

A

Hydrogen Bonds

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4
Q

Water forms ____________ with polar solutes

A

Hydrogen Bonds

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5
Q

Hydrogen bonds are strongest when the bonded molecules are oriented in a _______________

A

Straight line

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6
Q

Water interacts electrostatically with _________ solutes

A

Charged

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7
Q

Polar molecules are __________

A

hydrophilic

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8
Q

Nonpolar molecules are ___________

A

Hydrophobic (such as lipids and waxes)

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9
Q

The strength/ forces of ionic interactions in a solution depends on the what formula

A

F= Q1 Q/Er2 (E for water at 25 Celsius is 78.5)

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10
Q

For every nonpolar solvent benzene E is ______

A

4.6

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11
Q

Ionic interaction between dissolved ions are much stronger in less __________ environments

A

polar

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12
Q

Nonpolar gases such as CO2, O2, & N2 are poorly in ________

A

Water

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13
Q

Polar gases such as NH3, NO, H2S dissolve easily in ___________

A

Water

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14
Q

Amphipathic

A

Compounds containing regions that are both polar & nonpolar regions

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15
Q

Hydrophobic effect

A

When the nonpolar regions of the molecules cluster together to make the smallest hydrophobic area to the aqueous solvent & the polar region are arranged to maximize their interaction with the solvent (in an amphophilic compounds)

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16
Q

Micelles

A

Are the stable structures of amphipathic compounds in water

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17
Q

Noncovalent interactions

A

Are hydrogen bonds, ionic bonds, hydrophobic &van der waals interactions (weaker than covalent bonds)

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18
Q

__________ are crucial to macromolecular structure & function

A

Weak interactions

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19
Q

Interactions driven by the ______________ are also much weaker than convalent bonds

A

Hydrophobic effect

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20
Q

Hydrophobic interactions

A

Forces that hold nonpolar regions of the molecules together

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21
Q

______________ effect the colligative properties of aqueous solutions

A

Solutes

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22
Q

Water tends to move from ________ to ______ concentrations

A

High to low

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23
Q

When water molecules move from high to low concentrations they produce _____________

A

Osmotic pressure

24
Q

Osmotic pressure

A

Is the force needed to resist water movement

25
Q

Osmotic pressure equation:

A

∏= icRT

26
Q

Osmosis

A

Water movement across a semipermeable membrane driven by difference in osmotic pressure

27
Q

Isotonic solution

A

When the solution of osmolarity is equal to the outside of the cell (doesnt gain or lose water)

28
Q

Hypertonic solution

A

Higher osmolarity than the outside of the cell, the cell shrinks as water moves out

29
Q

Hypotonic solution

A

Lower osmolarity than the outside of the cell, the cell swells as water moves in

30
Q

Osmotic lysis

A

Bursting of a cell

31
Q

The ionization of water is expressed by an ______________

A

Equilibrium constant

32
Q

Kw is what

A

The ion product of water at 25 Celius

33
Q

At 25 Celius Kw value is what ?

A

1 x 10-14 M2

34
Q

Neutral pH

A

When there are equal concentrations of H+ & OH-

35
Q

pH equation is what?

A

pH= -log{[H+] (when pH is greater than 7 its basic & when its lower than 7 its acidic)

36
Q

When pH is below 7.4 its called ________ & when its above 7.4 its called ________

A

acidosis, alkalosis

37
Q

_______ are proton donors & ________ are proton acceptors

A

Acids, Bases

38
Q

What is the pKa equation?

A

pKa = -log Ka (the stronger the acid the lower the pKa)

39
Q

_________ reveal the pKa of a weak acid

A

Titrations curves

40
Q

A tritration curve is pH on the _____ axis & base added (usually NaOH) on the _____ axis (it shows the pKa of a weak acid)

A

y, x

41
Q

_________ are mixtures of weak acids & their conjugated bases

A

Buffers

42
Q

Buffers

A

Are aqueous systems that tend to resist changes in pH when small amounts of acid (H+) or base (OH-) are added

43
Q

The midpoint of the titration curve (the pH value) & 1 pH unit out is the ____________ region

A

Buffering

44
Q

During the buffering region whether H+ or OH- is added the pH barely _______

A

Change (stays the same basically)

45
Q

The _________________ equations relates pH, pKa, & buffer concentration

A

Henderson-Hasselbalch equation

46
Q

What is the Henderson-Hasselbalch equation?

A

pH=pKa + log [H+]/[HA]

47
Q

The pKa of a weak acid is equal to the _____ of the solution at the midpoint of a titrations curve

A

pH

48
Q

Weak acid or bases buffer cells & tissues against _____ change

A

pH

49
Q

The two important biological buffers are the ____________ & ____________ systems

A

Phosphate & bicarbonate systems

50
Q

The phosphate system act in the _______ of the cell consist of H2PO4- as proton donor & H2PO42- as proton acceptor

A

Cytoplasm

51
Q

The phosphate buffer system pKa & pH is ________ & resist pH changes between 5.9 & 7.9

A

6.86

52
Q

Blood plasma is buffered in part by the ________ system which has carbonic acids HCO3- (Proton donor) & bicarbonate (HCO-) (as proton acceptor)

A

Bicarbonate

53
Q

____________ buffer system is an effective buffer when the pH = 7.4

A

Bicarbonate

54
Q

H2CO3 pKa at 37 Celius is what?

A

3.57

55
Q

Condensations reactions

A

Water is eliminated

56
Q

Hydrolysis reactions

A

Cleavage accompanied by the addition of the elements of water

57
Q

Hydrolases

A

Hydrolysis reaction catalyze by enzymes (are exergonic & they produce two molecules from one)

Biochemistry (26 decks)

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