Chem 153A - Midterm 2 Exam With Complete Solutions
100% 2025/2026
Instructions (please read carefully)
1. The exam consists of 7 questions (12 pages total)
2. Pen is preferred but if you use a pencil you MUST write dark
3. Take the time to write your name and ID on EVERY page (points will be deducted
otherwise!)
4. Do NOT write on the back of any page of the exam as we don’t scan the backs of pages.
If you cannot fit your answer in the provided space, write your answer on Page 12.
5. If you are in need of assistance, please raise your hand quietly. Do your best!
1
, First and Last Name SID-------------------------
1. Carbohydrates and lipids (13 pts)
a. (4 pts) Consider the monosaccharides in a b
the disaccharide on the right.
i. What is true about these two
monosaccharides?
neither can switch their anomeric form ‘a’ can switch its anomeric form but ‘b’ can’t
‘b’ can switch its anomeric form but ‘a’ can’t both can switch their anomeric form
ii. Which of the following is a correct description of the glycosidic
bond above?
β-1,4 α-1,1 α-1, α-4
α-1,4 α-1, β-1 α-1, α-1
b. (4 pts) A linear hexose goes through a cyclization reaction.
i. On the linear structure, circle the
functional group that initiates
*
the cyclization reaction and star
(*) the group being attacked.
ii. On the cyclic structure, star (*)
the anomeric carbon.
c. (5 pts) Two TAGs are transported from the intestine to the liver.
i. An intestinal epithelial cell passes the pair of TAGs into the
lymphatic system for transport. Given the aqueous nature of the
lymph, what issues will be created by this transport and how are
they solved? Provide structural details of the transport mechanism.
As TAGs are hydrophobic, transport through an aqueous environment could
cause aggregation of the insoluble TAGs. The solution is the use of lipoproteins,
micelle-like structures with hydrophilic exteriors and hydrophobic interiors
(where the TAGs are stored)
ii. In the liver, one of the TAGs is subjected to lipolysis, releasing lauric
acid (12:0) and stearic acid (18:0). Both fatty acids then proceed to
beta-oxidation. How many acetyl-CoA will stearic acid produce
relative to lauric acid?
stearic acid will produce 12 more acetyl-CoA stearic acid will produce 3 more acetyl-CoA
stearic acid will produce the
stearic acid will produce 6 more acetyl-CoA 2
same amount of acetyl-CoA
100% 2025/2026
Instructions (please read carefully)
1. The exam consists of 7 questions (12 pages total)
2. Pen is preferred but if you use a pencil you MUST write dark
3. Take the time to write your name and ID on EVERY page (points will be deducted
otherwise!)
4. Do NOT write on the back of any page of the exam as we don’t scan the backs of pages.
If you cannot fit your answer in the provided space, write your answer on Page 12.
5. If you are in need of assistance, please raise your hand quietly. Do your best!
1
, First and Last Name SID-------------------------
1. Carbohydrates and lipids (13 pts)
a. (4 pts) Consider the monosaccharides in a b
the disaccharide on the right.
i. What is true about these two
monosaccharides?
neither can switch their anomeric form ‘a’ can switch its anomeric form but ‘b’ can’t
‘b’ can switch its anomeric form but ‘a’ can’t both can switch their anomeric form
ii. Which of the following is a correct description of the glycosidic
bond above?
β-1,4 α-1,1 α-1, α-4
α-1,4 α-1, β-1 α-1, α-1
b. (4 pts) A linear hexose goes through a cyclization reaction.
i. On the linear structure, circle the
functional group that initiates
*
the cyclization reaction and star
(*) the group being attacked.
ii. On the cyclic structure, star (*)
the anomeric carbon.
c. (5 pts) Two TAGs are transported from the intestine to the liver.
i. An intestinal epithelial cell passes the pair of TAGs into the
lymphatic system for transport. Given the aqueous nature of the
lymph, what issues will be created by this transport and how are
they solved? Provide structural details of the transport mechanism.
As TAGs are hydrophobic, transport through an aqueous environment could
cause aggregation of the insoluble TAGs. The solution is the use of lipoproteins,
micelle-like structures with hydrophilic exteriors and hydrophobic interiors
(where the TAGs are stored)
ii. In the liver, one of the TAGs is subjected to lipolysis, releasing lauric
acid (12:0) and stearic acid (18:0). Both fatty acids then proceed to
beta-oxidation. How many acetyl-CoA will stearic acid produce
relative to lauric acid?
stearic acid will produce 12 more acetyl-CoA stearic acid will produce 3 more acetyl-CoA
stearic acid will produce the
stearic acid will produce 6 more acetyl-CoA 2
same amount of acetyl-CoA
