Name _______________________
BIOCHEMISTRY 410-505
EXAM 2A (100 PTS)
October 25, 2002
Answer Questions 1-28 on Scantron
84 pts
Each question has a maximum value of 3 points. The best answer is full value, the second best is one point
1.
If your doctor told you to avoid saturated fats in your diet, you should especially avoid foods that contain:.
a) oleic acid
b) stearic acid
c) triolein
d) tristearin
e) glucose, fructose or sucrose
2.
A molecule of ATP contains which purine base in its structure:
a) adenosine
b) amylose
c) alanine
d) adenine
3.
4.
In DNA, cytosine will always be paired with:
a) thymine
b) uracil
c) ribose
e) adenylate
d) phosphate
e) guanine
One complete turn around the axis of a DNA molecules requires _____bases in one strand:
a) 10.5
b) 3.4
c) 20
d) 12
e) 1.33
5.
A trinucleotide contains this many phosphate molecules in phosphodiester linkage?
a) 3
b) 4
c) 2
d) 1
e) none
6.
To melt at a temperature lower than the melting point of oleic acid, a fatty acid must have at least:
a) 3 double bonds
c) 18 carbons
e) 2 double bonds
b) 1 double bond
d) 16 carbons
7.
A 5-deoxyketohexose was isolated from a primitive bacterium. Having never before seen this sugar, predict the
number of possible straight-chain isomers of this sugar:
a) 5 or more
b) 4
c) less than 4
d) 2
e) 1
8.
In problem 7, how many straight chain D isomers are possible?
a) 1
b) 2
c) 3
9.
d) 4
e) none
Vitamin C is classified as a lactone. The definition denotes what specific group in the molecule?
a) an internal ring-forming ester
d) one ene-diol as opposed to one enol bond
b) a double bond between two keto groups
e) a tendency for the molecule to lactonize
c) a phosphate attached to the anomeric carbon
10. In DNA sequence analysis (dideoxy reagent) the distance between successive peaks in the chromatogram is:
a) one base
b) 10 bases
c) 100 bases
d) 5 bases
e) it varies from 1-10
11. As a biochemistry student you should know that the total number of optical isomers of an D-aldopentose as it
would exist in solution is:
a) 2
b) 8
c) 4
d) 10
e) 16
12. An unknown disaccharide was derived either from hyaluronate or amylose. What is the best procedure that
would allow you to determine the correct choice?
a. test for a glycosidic bond in the molecule
d) test to see if there are 2, 6 carbon sugars
b. titrate it with NaOH
e) test for nitrogen or sulfur
c. test to see if the disaccharide is reducing
13 Suppose you isolated a fat soluble carbohydrate from brain tissue. Because you took a biochemistry course,
you should know that the compound you are studying is likely to be:
a) sphinogomyelin
c) cholesterol bound to a carbohydrate
e) DNA or RNA
b) a cerebroside
d) glycogen
14. How many sugars in the oligosaccharide of blood group O are NOT found in blood group A?
a) none
b) one
c) two
d) three
e) all of them
15. How many OH groups in D-glucose (no ring) have a different right-left (steric) orientation from L-glucose
a) none
b) one
c) two
d) three
e) all of them
16. Which of the following is an omega 3 fatty acid:
a) stearic acid
c) cis 9,12, 15 linolenic acid
6,9,12
b) cis 
linolenic acid
d) cis 9 oleic acid
e) none are
17. Which of the following has an 1-4, 1-6 bond in the molecule
a) glycogen
b) amylose
c) sucrose
d) cellulose
18. What class of lipids has the amino acid serine in the structure?
a) sphingolipids
b) acylglycerols
c) sterols
e) none have
d) acylglycerol phosphates
e) none
19. What class and molecules of carbohydrates have sulfur in the structure?
a) heteropolysaccharides
c) the chondroitins
e) all of the above
b) glycosaminoglycans
d) heparin
20. Which molecule below would not be found in the cell membrane
a) sphingomyelin
c) ganglioside GM1
e) tripalmitin
b) phosphatidylcholine
d) phosphatidylinositol
21. 7-dehydrocholesterol is used in the synthesis of:
a) Vitamin A
c) estradiol
b) Vitamin D3
d) testosterone
e) either estrogen or testosterone
22. Carbohydrates are NOT attached to proteins via:
a) O-glycosidic bonds to serine
c) N-glycosylamine bonds to asparagine
b) O-glycosidic bonds to threonine d) N-glycosylamine bonds to glutamine
e) all of the above are used
23. An example of a hemiketal is:
a) D-fructose
b) -D-fructose c) D-glucose
e) methyl -D-fructoside
d) -D-glucopyranose
24. Which molecule can NOT form micelles when placed in an aqueous solution?
a) cholesterol ester
c) oleic acid
e) all would form micelles
b) stearic acid
d) arachidic acid
25. If hydrolysis of a fat gave glycerol, palmitic acid, oleic acid and phosphate as products, it is likely the fat was:
a) a diacylglycerol
c) lecithin
e) a storage fat
b) phosphatidic acid
d) cholesterol ester
26. If you also found choline in the hydrolysate in problem 25, what would be fat:
a) a diacylglycerol
c) lecithin
e) a storage fat
b) phosphatidic acid
d) cholesterol ester
27. In order for 2H+ ions to enter a cell, one Ca2+ must leave. This is an example of:
a) cation exchange
b) symport
c) antiport
d) active diffusion
e) uniport
28 The sodium/potassium ATPase in the cell membrane requires ATP to drive the removal of Na + in exchange for
a K+. According to your text book, this is an example of:
a) primary active transport
c) secondary active transport
e) selective diffusion
b) competitive activation
d) non-mediated transport
SHORT ANSWERS
5 pts
1. Calculate the maximum chemical potential difference attainable when cells equilibrated at 37 oC against 0.1 M
sucrose are suddenly placed in a solution of 0.2 M sucrose at the same temperature. (SHOW ALL WORK)
Attaining equilibrium means that the concentration of sucrose inside the cell is 0.1 M., i.e., C in = 0.1 M, Cout = 0.2 M
G = RT ln [Cin]/[Cout]
or 2.303RT Log [Cin]/[Cout]
= 8.314 x 310 ln 0.5
= -1.79 kJoules
5 pts
2. DRAW and NAME the structure of EITHER your favorite UNSATURATED FATTY ACID or STEROID
HORMONE. (Hint: Cholesterol is not a steroid hormone). (Hint: don’t draw both).
Unsaturated could be oleic, linoleic, linolenic, archidonic etc.
Steroid hormone could be estradiol, testosterone, cortisone, corticosterol etc
CH2OH
9 pts
O
H
HO
CH2OH
H
O OH
OH H O OH H
H
H
H OH
H OH
Name the bond and the orientation of the bond that is
holding the two sugars together
Beta 1-4 glycosidic bond
H
O HC O C-CH2(CH2)nCH3 Name the bond that is holding the fatty acids to glycerol
moiety
CH3(CH2)nC O CH O
Ester bond
HC O P O
H
O
O
O OH
O
O
P
Name the bond that is joining the two ribose units
together (be specific)
Phosphodiester bond
O
CH2
O
HO OH
Check here if you would like your exam handed back
separately and not placed in a pile with the other exams
Multiple Guess _____
Short Answer: _____
TOTAL