Download Practice Problems for Exam 3

Practice Problems for Exam 3
CHEM 1407 and 1408
1. Give the general formula or structure for the following :
(a) carboxylic acid
(b) 2 amide
(c) unionized amino acid
(e) 1 amide
(f) 3 amide
(g) prostaglandins
(i) fat
(j) wax
(k) protein backbone
(d) steroid
(h) ester
(l) amino acid in zwitterion form
2. Complete the following general chemical equations by writing the name of all the expected products. If no reaction
occurs, write no reaction.
H+
(a)
ester + H2O — > ?
—>
?
(b)
carboxylic acid + NH3
(c)
H+
steroid + H2O —>
(d)
carboxylic acid
(e)
ester +
(f)
2 amine + carboxylic acid
(g)
carboxylic acid
(h)
amide
(i)
H+
triglyceride + H2O —>
(j)
cat
carboxylic acid + 3 amine —> ?
3. Define:
?
+ NaOH —>
H2SO4 (aq) —>
+
?
cat
—> ?
H+
alcohol —> ?
+
H+
—>
H2O
?
a) Hydrophobic
?
?
b) Hydrophilic
4. What functional groups are found in the following. Name and/or draw the structure.
a) amino acid
b) wax
c) spingolipid
d) fatty acid
e) protein
f) triglyceride
g) glycerophospholipid
5. Name the following compounds.
CH3 CH3
a)
HOOCCH2CHCHCHCH2CH3
b)
CH3CH2CH2OOCCH2CH2CH3
CH2CH2CH3
c)
CH3CH2CH2CON(CH3)2
6. Draw the structure of:
a) propanamide
b) 4-bromo-3,3-dimethylpentanoic acid
c) Isopropyl 2-methylbutanoate
2
COO+
7. Given
H3NCHCH2COOa) What is the R group of this amino acid?
b) Identify the alpha carbon.
8. a) What are the four types of R groups found in amino acid structure?
b) Give examples of each.
9. a) Discuss the differences between saturated and unsaturated fats and give an example of each type.
b) Which type would cause the brick-red color of Br2 to disappear?
c) Which type is associated with heart disease?
10. a) What structural feature do all steroids contain? b) Give examples of steroids.
11. Draw the zwitterion structures of:
a) valine ( R = isopropyl group)
b) alanine ( R = CH3)
c) leucine ( R = isobutyl group)
12. a) What is the general structure of a soap?
b) What type of reaction produce soaps?
c) How does soap clean?
13. Describe each of the following structures of a protein:
a) 1 structure
b) 2 structure
c) 3 structure
d) 4 structure
14. Given the following organic molecules, put them in order of highest to lowest boiling point?
CH3CH2COOH;
Propanol;
CH2=CHCH3;
Ethyl methyl ester;
(CH3)2CHCONHCH3
15.What are the products of the hydrolysis reaction of the following molecules? If no reaction occurs, write no reaction.
(a) glycerophospholipids
(b) fatty acid
(c) triglyceride (or fat)
(d) wax
(e) protein
(f) prostaglandin
(g) sphingolipid
16. a) Draw a picture of an alpha helix. What are some of its characteristics?
b) Draw a picture of the pleated sheet. What are some of its characteristics?
17. Name the 6 different categories of lipids.
18. a) Draw the backbone of a pentapeptide?
b) Circle the amide linkage(s).
c) Underline peptide linkage(s).
d) Put a box at the place where the R groups of the peptide should be.
19. a) What functional groups are present in an unionized amino acid?
b) Are these functional groups basic, acidic or neither?
c) Will these functional groups lose or gain H+ ?
d) Draw the structure(s) after the lose or gain of the H+.
e) Are the new groups formed after the lose/gain of a proton, a conjugate base or conjugate acid?
20. Describe the difference in structure between a fatty acid and a fat.
21. List two different physical or chemical properties of:
a) carboxylic acids
b) amides
c) amino acids
3
22. Complete and balance the following reactions. If no reaction occurs, write no reaction.
H+
a)
(CH3)2CHCOOCH2CH3 + H2O —>
?
b)
c)
d)
e)
(CH3)2CHCOOH + H2O --------> ?
O
H+
CH3CNHCH3 + H2O -----> ?
(CH3)2CHCO2H + LiOH -----> ?
cat
----> ?
CH3COOH + H2N–
23. Given the following forms of alanine:
+
+
Which one exists:
H3NCH(CH3)COOH3NCH(CH3)COOH
a) at the isoelectric point
(1)
(2)
b) at low pH
H2NCH(CH3)COOc) at pH = 7
H2NCH(CH3)COOH
d) in solid state
(3)
(4)
e) at high pH
f) which one does not actually exist in any aqueous solution?
g) When alanine reacts with HCl, which form is present after the reaction is complete?
h) Would you expect alanine’s isoelectric point to be closer to acidic, neutral, or basic pH?
24. a) Draw the structure for: Ser– Asp– Val–Tyr – Arg
b) Is this a protein?
25. a) Draw the product(s) formed from the reaction between 2-methyl-2-propanol and pentanoic acid.
b) What type of reaction is this?
26. Which lipids are nonsaponifiable? Saponifiable?
27. Look up the following amino acid structures. Assuming that they are part of a protein’s 1 structure and not as the
individual amino acids, answer the following questions.
Ile
Arg Tyr
Phe Glu
a) Which pair(s) can form hydrogen bonds to each other in a 3 or 4 protein in structure?
b) Which pair(s) can form hydrophobic interactions to each other in a 3 or 4 protein structure?
c) Which pair(s) can form disulfide linkages to each other in a 3 or 4 protein structure?
d) Which pair(s) can form salt bridges to each other in a 3 or 4 protein structure?
28. What are the components (building blocks) of the following molecules?
d) ester
e) steroid
f) cephaline
a) fat
b) 2 amide c) wax
29. a) What protein structure or structures do the following denaturing agents affect?
b) What interaction(s) between the R groups is(are) being disrupted?
1) pH
2) radiation
3) organic solvents
4) reducing agent
g) prostaglandin
4
ANSWERS TO PRACTICE EXAM 3
CHEM 1413
O
R
1.
(a) RCOOH
(b) R-C-NHR
O
(c) H2NCHCOOH
(d)
O
(e) 1 amide R-C-NH2
(f) R-C-N-R
COOH
(g)
(h) RCOOR
R
(i) CH2OOC
O
CHOOC
(j)
O
(k) +H3NCHC(NHCHC)nNHCHCOO-
OOC
CH2OOC
(l) +H3NCHCOO-
= long chain alkyl group (saturated or unsaturated)
R
2. (a) alcohol + carboxylic acid
(b) 1 amide + water
(c) no reaction (no hydrolysis)
(d) carboxylate anion + sodium cation + water (acid-base reaction)
(e) carboxylic acid + alcohol (hydrolysis but no acid-base reaction)
(f) 3 amide + water
(g) ester + water
(h) carboxylic acid + ammonium ion (NH4+ or protonated 1 or 2 amine)
(i) glycerol + 3 fatty acids
(j) no reaction
3. a) water hater
b) water lover
4. (a) amine and carboxylic acid
and various others (R groups)
(b) ester
(f) ester
5. a) 5-Ethyl-3,4-dimethyloctanoic acid
(c) amide (mainly)
(d) carboxylic acid
(g) ester, phosphate, amino
b) Propyl butanoate
(e) amide (backbone
c) N,N-Dimethylbutanamide
CH3
6. a) H2NCCH2CH3
b) CH3CH(Br)CCH2COOH
O
7. a) R = CH2COO-
CH3
c) CH3CH2CHCOOCH(CH3)2
CH3
COO-
b)
+
H3NCHCH2COOcarbon
8. (1) nonpolar R group; such as an alkyl group (-CH3)
(2) polar but not ionizable; alcohols (-CH2OH), amides,
alkyl sulfides (-CH2SH)
(3) acidic; such as carboxylic acid group (-CH2COOH)
(4) basic; such as an amine
group (-CH2NH2)
5
9. a) see notes
b) unsaturated fats
c) saturated fats
10. a) four ring system (3 hexane; 1 pentane)
b) see note/book
11. a) +H3NCHCOO-
c)
b)
CH(CH3)2
+
H3NCHCOO-
+
H3NCHCOO-
CH3
CH2CH(CH3)2
12. a)
COO- Na+
b) saponification
c) the nonpolar alkane chain of the soap interacts
with the oily dirt/stain while the polar ionic part of the soap molecule interacts with water to be rinsed away.
13.
1 structure:
2 structure:
3 structure:
amino acid content and sequence (amide bonds)
local structure ( helix and pleated sheets); hydrogen bonding between backbone groups
overall 3-D molecule (twists, turns bends of molecule); interactions include hydrogen bonding
between R groups, salt bridges, disulfide linkages, hydrophobic interactions
4 structure: arrangement of multiple protein chains together to form a single protein; same 4 interactions as
the 3 structures
14. (CH3)2CHCONHCH3
CH3CH2COOH
Propanol
15. a) glycerol; phosphate; 2 fatty acids; amino group
d) long chain alcohol; fatty acid
Ethyl methyl ester
b) g) no hydrolysis
e) amino acids
CH2=CHCH3
c) glycerol; 3 fatty acids
f) no hydrolysis
g) sphingosine; 2 fatty acids; (phosphate/amino group or sugar)
16. a) see notes/book for picture; characteristics:
(1) consists of a single protein molecule
(2) hydrogen bonding between carbonyl and amine of backbone
b) see notes/book for picture; characteristics:
(1) consists of multiple protein molecule (or multiple parts of same)
(2) hydrogen bonding between carbonyl and amine of backbone
17. triglycerides; wax; steriod; eicosanoids; sphingolipids; glycerophospholipids
O
O
O
O
18. a) +NH3–CH– C–NH–CH–C–NH–CH–C–NH–CH–C–NH–CH–COO-
19. a) amine (NH2) and carboxylic acid (COOH)
c) amine will gain an H+; the carboxylic acid donates H+
e) NH3+ is a conjugate acid; COO- is a conjugate base
b) amine is basic, carboxylic acid is acidic
d) amine becomes NH3+; CA becomes COO-
20. The fatty acid is a long chain carboxylic acid. It is one of the component of a triglyceride. The fat is a molecule
composed of 3 fatty acids and a glycerol that undergo esterification to form the fat molecule (ester functional group).
21. a) acidic; polar; hydrogen bonding; react with bases; react with alcohols ...
b) neither acidic or basic molecules; most polar organic family (1 and 2 ); reacts with carboxylic acids; hydrolyzable ...
c) contain both acid and basic functional groups, solids at room temperature, water soluble, hydrogen bonding ...
6
22. a) (CH3)2CHCOOH + CH3CH2OH
b) (CH3)2CHCOO- + H3O+
c) CH3COOH + CH3NH2
d) (CH3)2CHCOO - + Li+ + H2O
e) CH3CNH–
+
H2O
O
23. a) (1)
24.
b) (2)
O
c) can’t tell
O
d) (1)
e) (3)
O
f) (4)
CH2COO- CH(CH3)2
h) neutral
O
NH2+
a) +NH3–CH– C–NH–CH–C–NH–CH–C–NH–CH–C–NH–CH–COOCH2OH
g) (2)
CH2 OH CH2CH2CH2NHCNH2
b) no, a pentapeptide
25. a) CH3(CH2)3COOC(CH3)3 + water
b) esterification or condensation
26. saponifiable: triglycerides; wax; sphingolipids; glycerophospholipids nonsaponifiable: steroids; eicosanoids
27.
a) Arg-Tyr; Arg-Glu; Tyr-Glu
b) Ile-Phe
c) none
d) Arg-Glu
28. a) glycerol and 3 fatty acids
b) carboxylic acid and 1 amine
c) long chain alcohol and fatty acid
d) carboxylic acid and alcohol
e) 4 ring system and long chain alcohol
f) glycerol; 2 fatty acids; phosphate; amino group
g) 5 membered ring system and long chain carboxylic acid
29. a) pH: 2 ; 3 ; 4
radiation: 2 ; 3 ; 4
organic solvents: 2 ; 3 ; 4
reducing agents: 3 ; 4
b)
pH:
hydrogen bonding and salt bridges
radiation:
hydrogen bonding and salt bridges
organic solvents:
hydrogen bonding and hydrophobic interactions
reducing agents:
disulfide linkage