Lesson 1

Question 1

proteins

Answer 1

repeating polymers of amino acids (proteins)

Question 2

nucleic acids

Answer 2

repeating polymers of nucleotides (DNA, RNA)

Question 3

lipids and facts

Answer 3

generally, repeating (-CH2) - units (Fatty acids, TAGs)

Question 4

Polysaccharides

Answer 4

repeating monosaccharide units (glycogen, cellulose, lactose, sucrose)

Question 5

why is the bond angle in water 104.5 instead of 109.5 degrees

Answer 5

lone pairs (nonbonding electron pairs) –> take up more space compared to bonding electrons

Question 6

comparing H2O to H2S - why does water have such a comparatively HIGH boiling point compared to H2S

Answer 6

the oxygen in H2O is more electronegative than Sulfur and is therefore better at H-bonding

Question 7

H-bond doners

Answer 7

H+ on oxygen, nitrogen, sulfur

Question 8

H-bond acceptors

Answer 8

lone pairs on O,N, and S(rarely)

Question 9

direction and distance relationship with H-bond strength

Answer 9

linear is stronger than askew
closer is stronger than farther

Question 10

collections of weak bonds are very () and highly ()

Answer 10

stable, flexible

Question 11

how often does water reorient itself

Answer 11

every 10^-7 seconds

Question 12

true/false: non polar solutes do not spontaneously dissolve in aqueous solution

Answer 12

true
- water molecules must become more ordered to minimize interactions with non-polar solute

Question 13

dispersion of lipids in H2O

Answer 13

each lipid molecule forces surrounding H2O molecules to become highly ordered

Question 14

clusters of lipid molecules

Answer 14

only lipid portions at the edge of the cluster force the ordering of water
- fewer H2O molecules are ordered, and entropy is increased

Question 15

micelles

Answer 15

all hydrophobic groups are sequestered from water; ordered shell H2O micelles is minimized, and entropy is further increased

Question 16

If you focus on the IMFs between the fatty acid chains of adjacent molecules as the micelle forms, is delta H for micelle formation positive or negative? Is heat transferred from the system (fatty acids( to the surrounding (aqueous buffer) or vice versa?

Answer 16

energy in the form of heat is released upon bond formation

delta H is negative
(remember that the entropy of micelle is difference from the entropy of the water molecules)

Question 17

true/false: polar head groups interact with water on both surfaces of the bilayer

Answer 17

true

Question 18

in general, the more polar, the more…

Answer 18

soluble in aqueous solution

Question 19

in general, the more highly charged (either + or - ) =

Answer 19

more soluble in aqueous solution

Question 20

true/false: water influences the structure of large and small biomolecules

Answer 20

true