Chapter 1 and 2

Question 1

What are the 4 major classes of biomolecules?

Answer 1

Proteins, carbohydrates, nucleic acids, and lipids

Question 2

What are the 4 most abundant elements?

Answer 2

CHON

Question 3

How many molecules is water bonded to in liquid?

Answer 3

3.4

Question 4

How many molecules is water bonded to in ice?

Answer 4

4

Question 5

Describe the structure of a water molecule.

Answer 5

Tetrahedral, 104.5º, sp3 hybridized oxygen, bent, polar with dipole moment towards the oxygen

Question 6

What are the four types of noncovalent interactions in order from strongest to weakest?

Answer 6

Hydrogen bonds, ionic bonds, hydrophobic interactions, and van der waals

Question 7

bond strength of hydrogen bond

Answer 7

3-7 kcal/mol

Question 8

what is hydrogen bond weakened in?

Answer 8

H2O

Question 9

what is an ionic bond and give an example of one?

Answer 9

Also known as electrostatic bond, ion pair, salt bridges or linkages, Occurs between charged atoms

Question 10

what is hydrophobic interaction and give an example of one?

Answer 10

Spontaneous clustering of nonpolar molecules in water, Requires non-polar species
Folding of proteins and formation of membranes

Question 11

what is a van der waal interaction and give an example of one?

Answer 11

Transient (temporary) electrostatic interaction, butter stick

Question 12

What are the solvent characteristics of hydrophilic molecules?

Answer 12

Polar, soluble in water (i.e. NaCl)

Question 13

What are the solvent characteristrics of hydrophobic molecules?

Answer 13

Nonpolar, insoluble in water (i.e. Hexane)

Question 14

What are the solvent characteristics of amphiphilic molecules?

Answer 14

• Contain both polar and nonpolar groups
• Form micelles in water (if not sterically hindered)
• Formation of biological membranes
• (i.e. ionized fatty acids)

Question 15

What is osmosis?

Answer 15

Spontaneous process in which solvent (water) moves from areas of low solute concentration to high solute concentration (via semipermeable membranes)

Question 16

what is osmotic pressure?

Answer 16

Pressure required to stop net flow of water across a membrane (through osmosis)

Question 17

what is isotonic?

Answer 17

No net movement of water Concentrations are equal inside and out

Question 18

what is hypotonic?

Answer 18

Concentration greater inside

Water enters cell, cell swells until it bursts

Question 19

what is hypertonic?

Answer 19

Concentration greater outside

Water flows out and cell shrinks

Question 20

Water _________ ionic interactions.

Answer 20

weakens

Question 21

Strong acids and strong bases ________________ in water.

Answer 21

Dissociate completely

Question 22

What are buffers composed of?

Answer 22

Weak acid and its conjugate base

Question 23

What is the function of buffers?

Answer 23

To keep pH near constant, despite small additions of acid or base

Question 24

Concentration of a buffer is _______________________

Answer 24

The sum of acid plus salt

Question 25

What are the three physiological buffers?

Answer 25

Phosphate buffer
Bicarbonate buffer
Protein buffer

Question 26

what is the phosphate buffer important for?

Answer 26

Intercellular fluid

Question 27

what is the bicarbonate buffer important for?

Answer 27

Blood plasma

Question 28

What is the length of a covalent bond?

Answer 28

1 Å

Question 29

What is the length of an h-bond?

Answer 29

1.7-1.8 Å