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1) Biochemistry I > Water > Flashcards

Water Flashcards

1
Q

Name the four macromolecules.

A

Protein, carbohydrate, lipid, nucleic acids

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2
Q

What is the monomer unit of protein?

A

Amino acids

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3
Q

What is the monomer unit of carbohydrate?

A

Glucose

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4
Q

What is the monomer unit of lipids?

A

Glycerol and fatty acids

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5
Q

What is the monomer unit of nucleic acids?

A

Nucleotide

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6
Q

Name an example of protein in animals.

A

Insulin in pancreas

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7
Q

Name an example of carbohydrate in animals.

A

Glycogen in liver

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8
Q

Name an example of lipid in animals.

A

Fat surrounding the kidneys

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9
Q

Name an example of nucleic acids in animals.

A

DNA in the cell nucleus

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10
Q

Why do plants use starches for energy? Compare the process with glycogen break down.

A

Since they do not require as much energy, breaking down starches is a slower process than glycogen

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11
Q

Which is easier to carry around: fat or sugar? Why?

A

Fat since it consumes less energy than glycogen

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12
Q

In the proton hopping reaction, where does the equilibrium lie?

A

On the H2O + H2O side

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13
Q

What is the proton hopping (or ionization of water) reaction?

A

H2O + H2O –> H3O+ + OH-

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14
Q

What are the benefits of the high heat of vaporization of water?

A
  • Good temperature regulator

- Good evaporative (requires massive amount of energy –> you don’t lose too much)

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15
Q

What are the benefits of the high specific heat capacity of water?

A
  • Prevents dramatic temperature changes

- Good heat buffer

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16
Q

Name three physiochemical properties of the water molecule.

A

1) High heat of vaporization (2,260J/g)
2) High specific heat capacity (4.2 J/goC)
3) Boiling point is 100oC

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17
Q

Define electronegativity.

A

Electronegativity is the ability of an atom to attract electrons to itself.

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18
Q

What creates a dipole moment?

A

A difference in electronegativity between two atoms/molecules.

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19
Q

What are the consequences of a dipole moment?

A
  • Partial negative charge on the more electronegative atom/molecule
  • Partial positive charge on the least negative atom/molecule
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20
Q

What accounts for all the characteristics of water?

A

Hydrogen bonding

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21
Q

Define hydrogen bonding.

A

A hydrogen bond is a type of interaction between an electronegative atom and a hydrogen atom bonded to another electronegative atom.

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22
Q

Without hydrogen bonding, what would happen to water at room temperature?

A

Water would be gas at room temperature

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23
Q

Are hydrogen bonds static? What do they depend on?

A

No, the number of bonds change through time and depend on the temperature.

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24
Q

What happens when you freeze cells? What would happen to its organelles?

A

The cell would burst.

Lattices would form and puncture/damage the cells organelles.

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25
Q

How would you freeze cells without destroying them?

A

Cryopreservatives

Cover the material with cryoprotectant coating

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26
Q

Are hydrogen bonds stronger or weaker than covalent bonds?

A

Covalent > Hydrogen

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27
Q

What makes ice float on liquid water?

A

The crystal lattice structure makes ice less dense than liquid water

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28
Q

Describe Gibbs Free Energy Equation

A

Free Energy Change = Enthalpy Change - T(Entropy/Randomness)

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29
Q

Is a positive or negative enthalpy favorable? Why?

A

Negative, since it means that it does not require energy and thus can occur spontaneously

30
Q

Why does ice turn to water and water turn to gas spontaneously if their enthalpy is positive?

A

Because the entropy (randomness) is superior to the enthalpy

31
Q

Why does boiling water at 100oC stay at 100oC?

A

Because all the energy will go into breaking hydrogen bonds to transform H2O (liquid) into H2O (gas).

32
Q

How will the boiling point of water change if the altitude increases? Why?

A

If the altitude increases, pressure decreases, less energy to bring water to bp, so bp decreases

33
Q

How will the boiling point of water change if the altitude decreases? Why?

A

If the altitude decreases, pressure increases, more energy to bring water to bp, so bp increases

34
Q

Why do we want relatively weak bonds for biological molecules?

A

Since they are reversible, they act like velcro

35
Q

What does the expression “strength in numbers” mean in biochemistry?

A

Multiple weak bonds are very successful for biological molecules

36
Q

Place the bond types in order of most energy, to least energy.

A

1) Covalent
2) Ionic
3) Hydrogen
4) Hydrophobic
5) Van der Waals

37
Q

What is water a good solvent for? Why?

A
  • Charged and polar (hydrophilic) substances

- Since it has a dipole moment

38
Q

How will water act around polar substances?

A

It will reorient itself and form a non-permanent sphere of hydration

39
Q

Name some examples of substances that water is a good solvent for.

A
  • Amino acids and proteins
  • Small Alcohols
  • Carbohydrates
  • Salts
40
Q

Why is water a good solvent for salts?

A

Because the dissolution of salts is energetically favorable due to the increase in entropy.

41
Q

What is water a bad solvent for?

A
  • Nonpolar (hydrophobic) substances
42
Q

Name some examples of substances that water is a bad solvent for.

A
  • Nonpolar gases
  • Fatty acids
  • Oils and waxes
  • Hydrophobic amino acids
  • Solvents such as benzene, octanol, hexane
43
Q

How will water act around nonpolar substances?

A

It will form a cage around nonpolar compounds and DECREASE entropy (thermodynamically infavorable)

44
Q

What does amphipathic mean?

A

Containing both polar and nonpolar domains

45
Q

What is a micelle?

A

Aggregate of amphipathic molecules in water

46
Q

Why do amphipathic molecules arrange themselves in micelles?

A
  • Decreases surface area exposed to water
  • Entropy is increased (thermodynamically favorable)
  • Creates a sphere of hydration
47
Q

What is the hydrophobic effect? Name one of its biological consequences.

A
  • Non-polar molecules fold together to minimize contact with water
  • Protein folding
48
Q

If the partition coefficient indicates that there is a higher concentration in octanol than in water, is the substance polar or non-polar?

A

Non-polar

49
Q

If the partition coefficient indicates that there is a higher concentration in water than in octanol, is the substance polar or non-polar?

A

Polar

50
Q

When do hydrogen bonds occur?

A

When a hydrogen atom is sandwiched between two electron-attracting atoms (usually O or N)

51
Q

When do ionic bonds occur?

A

When two formal charges interact with each other

52
Q

When do hydrophobic bonds occur?

A

Two non-polar components form a bond to minimize interaction with water

53
Q

When do Van der Waals Interactions occur?

A

When uncharged atoms are brought close together, the electron density creates a dipole

54
Q

What is pH?

A

The measure of the number of protons in an aqueous solution.

pH = -log(H+)

55
Q

What is a conjugate base?

A

When a weak acid becomes deprotonated (A-)

56
Q

What is a conjugate acid?

A

A protonated weak acid (HA)

57
Q

What is a buffer? Why is it useful biologically?

A
  • Aqueous solution with a highly stable pH.

- Buffers regulate pH

58
Q

In a titration, what happens when HA and A- are equivalent?

A
  • pH = pKa

- Buffers are optimal

59
Q

What is the optimal buffering capacity? What is the buffering region?

A
  • When pH = pKa (when HA = A-)

- +/- 1pH unit around pKa

60
Q

What is a monoprotic system?

A
  • changes between HA and A- occur with the loss/gain of a single proton
  • One pKa
61
Q

What is a triprotic system? Give an example.

A
  • Changes between HA and A- occur with the loss/gain of three protons
  • ex: H3PO4
62
Q

If you add a base to a buffer, how would the concentrations change?

A

HA - base = new concentration of HA

A- + base = new concentration of A-

63
Q

If you add an acid to a buffer, how would the concentrations change?

A

HA + acid = new concentration of HA

A- - acid = new concentration of A-

64
Q

How does pH influence the absorption of drugs?

A

Where it is absorbed/How.

Ex: stomach is acid, but absorption only occurs when drug is in its conjugate base form, so no absorption in stomach

65
Q

What is osmosis?

A

The movement of water or salts through a semipermeable membrane to reach equilibrium.

66
Q

What does hypertonic mean for a cell?

A

Greater concentration of solutes outside of the cell, water moves out of the cell, which SHRIVLES

67
Q

What does hypotonic mean for a cell?

A

Lesser concentration of solutes outside of the cell, water moves into the cell, which BURSTS

68
Q

Why don’t plant cells shrivel or burst?

A

They have a cell wall that helps them adapt to large changes in osmotic pressure

69
Q

What is the pH of blood?

A

7.34-7.45

70
Q

The buffering capacity of a solution can be overcome by what?

A

By the addition of excessive acid or base

1) Biochemistry I (12 decks)

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