Module 2 Flashcards

1
Q

2 characteristics of water

A
  1. most abundant
  2. passive + active roles
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2
Q

passive role

A

forms structure in response to interaction with water

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3
Q

active role

A

water is a participant

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4
Q

O2 structure

A
  1. more electronegative than H+
  2. partial negative charge
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5
Q

does water have a permanent or non-permanent dipole?

A

permanent because of its electronegativity

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6
Q

what charge does Hydrogen have

A

partial positive

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7
Q

what do dipoles influence (2)

A
  1. the ability to form electronegative interactions with charged molecules
  2. the ability to form hydrogen bonds
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8
Q

what are amphipathic molecules?

A

have both polar and non-polar portions

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9
Q

what are hydrogen bonds

A

electrostatic interactions between an electronegative atom with H+ covalently bonded to another electronegative atom with free electron pair (O2 or N2)

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10
Q

Are Anti-parallel or parallel beta sheets more stable?

A

more stable than parallel sheets due to better geometry of H+ bonds

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11
Q

unique abilities of O2/N2

A

can serve as electron donors & acceptors

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12
Q

what is a H+ bond donor?

A

electronegatively charged atom that has H+ covalently attached

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13
Q

How many H+ bonds can H2O molecules form?

A

4 H+ bonds (2 acceptors, 2 donors)

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14
Q

advantage of H+ bonds between H2O molecules

A

confer great internal cohesion

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15
Q

how many H+ bonds does liquid H2O have?

A

3-4

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16
Q

what does electronegative mean?

A

an atom’s tendency to attract electrons to itself

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17
Q

what does permanent dipole mean?

A

uneven distribution of charge

18
Q

what does Van der waals forces mean?

A

interaction between permanent + induced dipoles

19
Q

when is attraction at its max in van der waals forces?

A

when 2 atoms are separated by the sum of radii

20
Q

what is the hydrophobic effect?

A

polar groups interact with water and non-polar regions away from water

21
Q

non-polar compounds dissolve ( ) in water

A

poorly

22
Q

non-polar side chains

A

form away from water

23
Q

polar side chains

A

on surface, away from water

24
Q

how do strong acids/bases dissociate in water?

A

they fully dissociate in water

25
Q

what does the folding of a polypeptide do to entropy?

A

decrease polypeptide entropy & increase water entropy

26
Q

what does the association of non-polar molecules do to entropy?

A

increase entropy

27
Q

true or false: H2O molecules around hydrophobic molecules are more ordered than pure water

A

true, because the introduction of non-polar molecule causes a decrease in entropy

28
Q

what is a titration curve?

A

the ratio of acid to its conjugate base changes over the curve

29
Q

what does a lower PKa value mean?

A

a stronger acid

30
Q

what does it mean when pH=PKa?

A

system is best ale to resist changes

31
Q

what form of the molecule is above the buffer region?

A

un-protonated (already donated the proton)

32
Q

what form of molecule is below the buffer region?

A

protonated (has not donated the proton yet)

33
Q

what is the Henderson-Hasselbalch equation?

A

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

34
Q

what is a buffer?

A

a solution that resists changes in pH caused by the addition of an acid or base

35
Q

what does a buffer consist of?

A

a weak acid + conjugate base

36
Q

what is an amphoteric molecule?

A

can serve as an acid or base (a molecule capable of donating and accepting protons)

37
Q

ionization of water equation

A

Keq= [H+] [OH-] / [H2O]

38
Q

which 2 functional groups undergo attractive electrostatic interactions?

A

carboxyl & guanidino

39
Q

hydrophilic molecules are…

A

polar (water loving)

40
Q

hydrophobic molecules are…

A

non-polar (water fearing)

41
Q

a hydrogen bond between a carbonyl & water molecule, the hydrogen atom is ( ) to the carbonyl group and ( ) to the oxygen of the water molecule

A

electrostatic associated, covalently linked