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Intro to Biochemistry > 3 - Water, pH, pK and buffers > Flashcards

3 - Water, pH, pK and buffers Flashcards

1
Q

4 Important properties of water

A

Chemical stability
Remarkable solvent properties
Role as biochemical reactant
Hydration

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2
Q

What type of geometry does water have

A

Tetrahedral

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3
Q

Why is water a dipole? Why type of bond does this make between H and O?

A

Water is a dipole because its negative and positive charge are separate and this makes the bonds polar.

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4
Q

What elements can hydrogen form HYDROGEN BONDS with?

A

Oxygen, nitrogen and fluorine

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5
Q

What two characteristics do hydrogen bonds have

A

electrostatic (opposite charges) and covalent (electron sharing) properties

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6
Q

Bonds ranked by strength (4)

A

Covalent (strongest)

Ionic
Van der Waals forces

Hydrogen Bonds (weakest)

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7
Q

Noncovalent interactions are electrostatic, list two noncovalent interactions.

A

Van der Waals forces and ionic interactions. Hydrogen bonds are mixed covalent and electrostatic.

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8
Q

A Van der Waal force occurs between what three types of dipoles?

A

Neutral
Permanent
Induced

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9
Q

How many hydrogen bonds can a single water molecule form with other water molecules?

A

4, although this usually only occurs in ice

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10
Q

What two characteristics help maintain an organism’s internal temperature? How?

A

High heat of fusion and high heat of vaporization

These properties are due to waters abundance in organisms.

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11
Q

What are solvation shells?

A

shells of solvent molecules that form around a solute species. With water, a hydration shell is formed around ions.

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12
Q

What is the name for water surrounded molecules that have nonpolar tails sticking into core and polar head sticking into water?

A

Micelles, amphipathic molecules form micelles when mixed with water.

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13
Q

What is the role of turgor pressure in plants

A

It allows them to grow by using osmotic pressure

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14
Q

What is Kw at standard conditions?

A

1x10^-14. This is temperature dependent, and therefore pH is temp dependent as well

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15
Q

What is the equation for pH?

A

pH = -log[H+]

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16
Q

What is the equation for pKa?

A

-log[Ka]

17
Q

What is Ka

A

The acid dissociation constant.

18
Q

What is acidosis and alkalosis

A

Certain diseases that can cause changes in pH that can be disastrous

19
Q

What do buffers do?

A

By following Le Chatelier’s principle buffers establish an equliibrium between buffers components. They shift the equilibrium in the direction that relieves stress

20
Q

What does the Henderson-Hasselbalch Equation show? And what is it?

A

Establishes the relationship between the pH and pKa for selecting a buffer.
pH = pKa + log([A-]/[HA])

21
Q

What is the enzyme responsible for bicarbonate buffer in the blood?

A

Carbonic Anhydrase

22
Q

What is phosphate buffer for?

A

Important buffer for intracellular fluids

23
Q

Can proteins act as buffers? If they can, what is an example?

A

Proteins are a significant source of buffering capacity (hemoglobin)

24
Q

When does water have a maximum number of hydrogen bonds formed? (eg. what state is it in)

A

When water has frozen into ice. It has an open, less dense structure as ice.

25
Q

What gives cytoplasm the properties of a gel? What is an advantage of this property?

A

It is a colloidal (evenly dispersed particles throughout)

Transition from gel to sol is important in cell movement. Converting an edge to sol makes the cell ‘flow’ that way.

26
Q

What type of force stabilizes the hydrophobic effect?

A

van der Waals interactions

27
Q

What is osmotic pressure?

A

The pressure required to stop the net flow of water across the membrane. It depends on solute concentration.

28
Q

What is osmosis?

A

The diffusion of water across a membrane. Because it is water, it flows to where the concentration gradient is lesser than where it came from.

29
Q

What is ionization?

A

The process of converting an atom or molecule into an ion by adding or removing charged particles such as electrons or ions.

Eg. converting H2O into H+ and -OH

Intro to Biochemistry (28 decks)

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