Biochemistry - carbohydrate metabolism
Exam Questions and Answers
Define catabolism and anabolism. What are the major functions of these two
processes? - ANSWER-catabolism - breakdown of proteins to AAs and starch to
glucose, yields energy (ATP)
anabolism - synthesis of AAs to proteins and glucose to starch, uses energy
What is glycogenesis, glycogenolysis, gluconeogenesis, and glycolysis? - ANSWER-
glycogenesis - formation of glycogen from glucose to be stored in liver.
glycogenolysis - breakdown of glycogen into glucose or lactate
glycolysis - glucose-6-P is broken down into pyruvate
gluconeogenesis - synthesizing glucose out of AA and non-hexose carbs
Describe the different steps in glycogen synthesis. - ANSWER-1. Conversion of glucose
to glucose 6-phosphate
2. then to glucose 1-phosphate
3. then to the monomer UDP-glucose.
4. The primer glycogenin (enzyme) polymerizes the first few glucose molecules
(elongation of molecule)
5. then the enzyme glycogen synthase takes over for further elongation and branching
until alpha(1->6) bonds
6. glycogen
Differentiate between the role of glycogenin and glycogen synthase in glycogen
synthesis. - ANSWER-glycogenin polymerizes the first few molecules, then glycogen
synthase takes over to finish glycogen
How is the glycogenolysis process in muscle different from liver? - ANSWER-muscle:
glycogen -> glucose 1-phosphate -> glucose 6-phosphate then glycolysis to LACTATE.
lactate processes to the TCS cycle to become pyruvate
liver: glycogen -> glucose 1-phosphate -> glucose 6-phosphate then glucose 6-
phosphatase converts it to GLUCOSE which is sent to the blood to distribute to other
organs
Discuss briefly the regulation of glycogenesis and glycogenolysis by glucose levels,
glycogen phosphorylase, and glycogen synthase. - ANSWER-synthesis and breakdown
of glycogen are spontaneous.
Exam Questions and Answers
Define catabolism and anabolism. What are the major functions of these two
processes? - ANSWER-catabolism - breakdown of proteins to AAs and starch to
glucose, yields energy (ATP)
anabolism - synthesis of AAs to proteins and glucose to starch, uses energy
What is glycogenesis, glycogenolysis, gluconeogenesis, and glycolysis? - ANSWER-
glycogenesis - formation of glycogen from glucose to be stored in liver.
glycogenolysis - breakdown of glycogen into glucose or lactate
glycolysis - glucose-6-P is broken down into pyruvate
gluconeogenesis - synthesizing glucose out of AA and non-hexose carbs
Describe the different steps in glycogen synthesis. - ANSWER-1. Conversion of glucose
to glucose 6-phosphate
2. then to glucose 1-phosphate
3. then to the monomer UDP-glucose.
4. The primer glycogenin (enzyme) polymerizes the first few glucose molecules
(elongation of molecule)
5. then the enzyme glycogen synthase takes over for further elongation and branching
until alpha(1->6) bonds
6. glycogen
Differentiate between the role of glycogenin and glycogen synthase in glycogen
synthesis. - ANSWER-glycogenin polymerizes the first few molecules, then glycogen
synthase takes over to finish glycogen
How is the glycogenolysis process in muscle different from liver? - ANSWER-muscle:
glycogen -> glucose 1-phosphate -> glucose 6-phosphate then glycolysis to LACTATE.
lactate processes to the TCS cycle to become pyruvate
liver: glycogen -> glucose 1-phosphate -> glucose 6-phosphate then glucose 6-
phosphatase converts it to GLUCOSE which is sent to the blood to distribute to other
organs
Discuss briefly the regulation of glycogenesis and glycogenolysis by glucose levels,
glycogen phosphorylase, and glycogen synthase. - ANSWER-synthesis and breakdown
of glycogen are spontaneous.
