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Biology > Biochemistry CH2 > Flashcards

Biochemistry CH2 Flashcards

1
Q

The process of life primarily takes place in _____ _____ _______, which is commonly referred to as ________ ________

A

Water based environments
aqueous solutions

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2
Q

what can shutdown without water and turn back on with it (metabolism etc)`

A

sea monkeys

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3
Q

Daily water exchange of typical human

A

Intake:
900 mL beverage
800 mL food
300 mL metabolic

Output:
1050 mL urine output
100 mL feces
850 mL sweat

2000mL total each

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4
Q

Water is what hybridization shape is water?

Electron domain geometry?

A

bent - 104.5 bond angle

sp3 tetrahedral

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5
Q

Waters unique properties (dissolves)

A

dissolves ionic substances (NaCl)

dissolves hydrogen bonding substances (C-OH N-H, carbs proteins amino acids)

Many polar substances

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6
Q

What does water not dissolve

A

Oily molecules (vegetable oil, Italian salad dressing)

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7
Q

Water colligative properties

A

Melting point - salt melts ice (sodium chlorine ions)

Osmotic pressure - Water higher concentration -> lower concentration (omsosis)

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8
Q

Autoionization (water chemistry)

A
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9
Q

Water melting and boiling point (celcius) @ 18g/mol

A

0 degrees melting point
100 degrees boiling point

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10
Q

heat of vaporization
@ 18g/mol

A

amount of calories per gram of water that it takes to vaporize water from a liquid to a gas

540 cal/g

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11
Q

H2S

A

Sp3 tetrahedral

bent electron configuration

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12
Q

Which is more dense, liquid or solid water?

A

liquid (ice cubes float, why lakes freeze top down)

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13
Q

Does water have a high heat capacity?

A

yes, amount of heat that its able to absorb before it heats up or vaporizes

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14
Q

Water attractive properties

A

water is attracted to itself and other things like coaster and the glass

(non covalent forces)

put a little salt on napkin so water can dissolve the ions

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15
Q

What are the arrows point towards (what does it mean)

A

Pointing towards the electronegative atom.

Indicate the direction of the electron density. The direction the arrow is pointing shows that the atom its pointing to has a more significant share of the shared electrons, hence has negative charge.

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16
Q

H2S C6H14 and CCl4 has lower … than water

A

Lower melting point, boiling point,, and heat of vaporization (6-11x)

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17
Q

Forces that occur between two molecules are called

A

non covalent forces

both attractive and repulsive exist but focusing on attractive

ex: water on penny, water beading up on waxed car

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18
Q

the attraction between any two molecule results from the presence of

A

+ and - charges

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19
Q

In non covalent forces, these charges are nearly always…

Are theese charges permanent?

A

partial positive and partial negative

no

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20
Q

Why do partial charges exist?

A

Difference in polarity, it is a difference in electronegativity.

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21
Q

Three types of non-covalent forces:

A

Hydrogen bonding
Dipole-dipole forces
London dispersion forces

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22
Q

Dipole-dipole forces

A

Common in polar molecules

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23
Q

If atoms have an unequal sharing of electrons, this means

A

the bond is polar

one partial positive and one partial negative end

similar situation to magnets

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24
Q

How would several molecules of HCl align

A

(maximizes dipole-dipole interactions)

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25
Q

What is the strongest dipole-dipole interaction?

A

H bonding

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26
Q

Why is acetone (organic molecule) a liquid and not a gas at room temperature?

A

dipole-dipole interactions

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27
Q

What is the strongest class of intermolecular forces

A

dipole-dipole

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28
Q

Hydrogen bonding

A

Any one donor can act as any one acceptor, doesn’t have to be N to N or O to O.

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29
Q

These are…

A
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30
Q

How many hydrogen bonds does a single water molecule form when it freezes?

A

About 4, 3.7.

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31
Q

What is responsible for waters unique physical properties such as high boiling and melting point?

A

Hydrogen bonding - strongest non-covalent forces

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32
Q

Which non covalent force is the weakest

A

London dispersion forces

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33
Q

What are london dispersion forces

A

Temporary arrangement of electrons within a molecule, when they bunch up at one side/spot of a molecule

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34
Q

Which property results in non polar molecules being able to interact with other molecules

A

London forces

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35
Q

Why can non polar molecules exist as liquids or solids

A

london forces

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36
Q

Do larger or smaller atoms and molecules experience greater london forces?

A

Larger, more electrons
They also have higher melting and boiling points as a result.

37
Q

Why can I2 be solid at room temperature, Br2 a liquid at room temperature while F2 and Cl2 are gases at room temperature?

A

Molecular weights
F2 - 38 g/mol
Cl2 - 70 g/mol
Br2 - 160 g/mol
I2 - 254 g/mol
Greater london forces yielding greater attractive forces because more electrons in larger molecules.

38
Q

Interaction strength (kcal)

A
39
Q

F = kq1q2/r^2

A
40
Q

Ordered water molecules hydrogen bonding network

A

clathrate

41
Q

Hydrophilic vs Hydrophobic

A

Hydrophilic - Water soluble (loves water).

Hydrophobic - Insoluble in water (hates water).

42
Q

Hydrophobic effect

A

Packing of nonpolar regions to minimize the interactions with water while the polar region interacts with water.

Driving force behind this is the spontaneous drive of water to bind to itself through hydrogen bonds.

43
Q

Water auto ionization, how much OH- and H+ is formed (molar)

A

1 * 10^-7 M

44
Q

Can many things be auto ionized?

A

Yes

45
Q

Write equilibrium constant expression for this reaction.

A
46
Q

What happens in equilibrium reactions? (double arrows going opposite directions)

A

Forward and reverse reactions are happening simultaneously.

No net change when at equilibrium but still happening just at the same rate.

47
Q

Write equilibrium constant for autoionization for water.

A
48
Q
A

Neutral would be = 1E-7

H+ =-8 or lower eg 10^-9, 10^-10 etc, then it is basic.

if OH- is of the same values then its acidic.

49
Q

pH scale (IMPORTANT)

A

Memory = H+ reflects the pH essentially

50
Q
A
51
Q

pH =

A

pH = -log[H+]

52
Q

Some bacteria live in streams that are acidic (pH = 3.2). What is the [H+] of the water?

How does this [H+] compare with the bacteria living in milk (pH = 6.5)?

A
53
Q
A
54
Q

What is the pH of cytoplasm for a typical human cell, and what is it called?

A

7.4, physiological pH

55
Q

Lysosomes have a pH of 5, physiological pH is 7.4, compare the concentration of H+ ions in lysosomes vs other organelles

A

Over 100x more H+ concentration in lysosomes vs other organelles. (around 250)

56
Q

Three primary types of molecules that dissolve in water

A

Ionic - NaCO3 & KCl
Polar - HCl & acetone (and other ketones)
Hydrogen bonding - Acetic acid and sugar

57
Q

What does Ka and pKa equal for this reaction?

A
58
Q

pKa =

A

pKa = -log[Ka]

59
Q

Acid Strength

A

HCl strongest
Methane weakest

Lower pKa stronger acid

60
Q

CH4 has pKa of 52, how easily would the CH bond break?

A

Would almost never happen

61
Q

What is a buffer?

A

Neutralizing any acid or base that will be put into the system.

Resists change in pH.

62
Q

A buffer is most effective within __ pH unit of pKa. For example, what should the buffer be for a pKa of 3.86?

A

1 pH unit
2.86-4.86 buffer range most effective.

63
Q

Buffering capacity

A

There is a limit to the amount of acid or base a buffer can neutralize.

If a buffer is 100mM then it has that much ability to be able to basorb H3O+ protons or OH-.

64
Q

Bicarbonate buffer system

A

Help offset any reactions that try to change the pH of the cell.

Effective in the bloodstream

Also the phosphate system, both effective at pH 7.4.

65
Q

Chemical reactions indicators

A

Light
- Heat exchange
Sound
Color change
- Bubble formation

66
Q

Three Thermodynamic Values

A

H - Enthalpy - heat and heat transfer.

S - Entropy - Randomness and disorder, more entropy more disorder.

G - Gibbs Free Energy - G = H - TS
ΔG = H - TΔS
T = temp units of kelvin

67
Q

If Gibbs free energy is (-) or (+) what does that mean?

A

(-): spontaneous
(+): nonspontaneous

68
Q

Give an example of a positive entropy and negative entropy reaction

A

Positive - One molecule breaking into two (more disorder)

Negative - Two proteins coming together to form one (more order)

69
Q

Give an example of a positive and negative enthalpy reaction

A

Positive - Heat flows in (endothermic)

Negative - Heat flows out (exothermic)

70
Q

Example of a spontaneous reaction. (Gibbs negative value)

A
71
Q

What supports non-spontaneous reactions

A

ATP

72
Q

Example of a nonspontaneous reaction. (Gibbs negative value)

A

Movement of muscle proteins

73
Q

is Glucose + ATP –> Glucose-6-P + ADP spontaneous or nonspontaneous?

A

Spontaneous (-) delta G

74
Q

Delta H is positive if heat flows (into or out of) the reaction

A

into

75
Q

In the uric acid example of icepack, is it spontaneous or nonspontaneous, delta H positive or negattive

A

Happened spontaneously, so delta G is negative, and delta H is positive because heat flowed into the reaction to produce the products. The ice pack is cold because the heat dissipates into the air, into the persons hand and into the reaction, which leaves the bag feeling cold.

76
Q

The movement of muscle proteins is (spontaneous or nonspontaneous)

A

nonspontaneous

But the ATP that is coupled to these reactions permits contraction.

77
Q

What is the shape of water

A

Bent

78
Q

What is autoionization and how is it important for water

A

Autoionization is when a compound/molecule reacts with itself which results in the formation of ions.

Water: It is important to water because it forms an H3O+ acid ion and OH- is the base ion, which allows water to act as a weak acid or a weak base. Autoionization of water is very indicative of its the chemistry of water.

79
Q

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

A

55.5M

80
Q

Define Keq

A

Equilibrium constant

Solids and liquids are left out of this equation. It tells us the extent of which the reaction proceeds in a forward direction.

Keq = products^coefficients / reactants^coefficients

81
Q

Define Kw

A

Kw is the ion product, it tells us the relationship of the concentration of the acid ion and the base ion in water.

Kw = [H+][OH-] = 1*10^-14

82
Q

Identify the acid, conjugate base, and proton in the following reaction.

A
83
Q

A buffer system has a pKa of 6.5, what is the effective buffering range?

A

5.5 to 7.5

84
Q

Calculate Ka value (equation)

A

Ka = [H+][A-] / [HA]

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 than weak acid B because weak acid A has a stronger pKa value which means its a stronger acid.

86
Q

Ice melts at room temperature. What is the sign for delta G in this reaction?

A

delta G will be negative, because the reaction is spontaneous

Entropy is gained times the temperature is greater than the enthalpy

Enthalpy is positive because the icecube is absorbing heat to melt but the enthalpy isnt greater than the temperature times the entropy, making the gibbs free energy negative

87
Q

Butane combusts in the air by the following reaction:
C4H10 (l) + 6.5 O2 (g) —-> 4 CO2 (g) + 5 H2O (g)

What is the sign of delta G, delta H, and delta S in this reaction?

A

ΔG is negative, it is a spontaneous reaction, there isn’t a case where it couldn’t be negative mathematically because
ΔH is negative

ΔH is negative because heat is released

ΔS is positive because it is a disorderly reaction as more gases are produced

88
Q

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

A

ATP is the energy source for the reaction, ATP has a large negative delta G that powers the nonspontaneous reactions.

Biology (14 decks)

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