Biologically Important Nucleotides and Questions For NEET, GPAT, CSIR NET, GATE, Pharmacist & Nursing Exam
Beside being the structural component of the nucleic acids, several nucleotides participate in various biochemical and physiological functions. Such nucleotides are known as biologically important nucleotides.
Adenosine tri-phosphate (ATP)
It serves as main source of energy for various metabolic pathways like fatty acid synthesis, glycolysis, protein synthesis etc. Its physiological functions include: muscle contraction, transmission of nerve impulses etc.
Adenosine mono-phosphate (AMP)
It is the component of various co-enzyme like NAD+, NADP+, FAD, coenzyme A etc. all these are majorly required in lipid, carbohydrate and protein metabolism
Cyclic-AMP
It is formed from ATP by adenylate cyclase enzyme. It serves as secondary messenger for hormones such as epinephrine and glucagon. Its other functions include:
- It activates the degradation of food items like fat and lipid and hence stimulate lipolysis and glycogenolysis
- It increases the secretion of gastric juice
- It also decreases the aggregation of platelets in blood.
Guanosine di-phosphate and guanosine tri-phosphate (GDP and GTP)
- It participates in the conversion of succinyl-CoA to succinate in TCA cycle.
- It also activates the adenylate cyclase enzyme
- It serves as energy source for protein synthesis
Cyclic-GMP
It is formed from GMP by guanylyl cyclase. It serves as secondary messenger and acts with opposite effect to that of cyclic-AMP. It works in relaxation of smooth muscle and vasodilation.
Uridine di-phosphate (UDP)
- Participate in glycogenesis
- UDP-glucose is required in galactose metabolism and for the synthesis of lactose
- UDP-glucuronic acid is required for detoxification reactions.
Cytidine tri-phosphate and cytidine di-phosphate (CTP and CDP)
These are required for the biosynthesis of various phospholipids. CDP-choline is involved in the synthesis of sphingomyelin.
Multiple Choice Questions MCQs
1. ATP, UDP, CTP etc are the example of which class?
A. Nucleotides
B. Nucleosides
C. Both
D. None
2. ATP serves as energy source in which pathway?
A. TCA cycle
B. Glycogenesis
C. Glycolysis
D. all of the above
3. From which nucleotide, cyclic-AMP is formed?
A. ATP
B. CTP
C. UDP
D. UTP
4. Match the following functions-
A. ATP 1. Participate in glycogenesis
B. cyclic-AMP 2. serve as source of energy in protein synthesis
C. GTP 3. Increases the secretion of gastric juice
D. UDP 4. transamination of nerve impulses
5. Which nucleotide works for vasodilation?
A. cyclic-GMP
B. ATP
C. cyclic-AMP
D. GMP
6. Which nucleotide serves as energy source for protein synthesis?
A. GDP
B. GTP
C. AMP
D. both A and B
7. Which nucleotide activates the lipolysis?
A. cyclic-GMP
B. ATP
C. cyclic-AMP
D. GMP
8. Which of the following statement is NOT true?
A. ATP stands for adenosine tetra-phosphate
B. Muscle contraction is the main function of ATP
C. GTP works as source of energy for protein synthesis
D. CDP is required for synthesis of phospholipids
9. Which nucleotide activates the adenylate cyclase enzyme?
A. GDP
B. GTP
C. AMP
D. both A and B
10. Which of the following nucleotide plays an important role in synthesis of phospholipids?
A. CTP
B. UTP
C. CDP
D. both A and C
11. What is the full form of ATP?
A. Adenyl tri-phosphate
B. Adenosine tri-phosphate
C. Adenosine tetra-phosphate
D. None of the above
12. Which type of base lies in CTP?
A. Pyrimidine
B. Purine
C. Both
D. None
13. AMP is component of which co-enzyme?
A. NAD+
B. FAD
C. NADP+
D. all of the above
14. Conversion of succinyl-CoA to succinate takes place in which pathway?
A. HMP-shunt
B. Glycogenesis
C. Glycolysis
D. None of the above
15. Which nucleotide is required in galactose metabolism?
A. ATP
B. CTP
C. UDP
D. UTP
ANSWERS:-
1. Nucleotides
2. Glycolysis
3. ATP
4. A – 4 B – 3 C – 2 D – 1
5. Cyclic-GMP
6. Both A and B
7. Cyclic-AMP
8. ATP stands for adenosine tetra-phosphate
9. Both A and B
10. Both A and C
11. Adenosine tri-phosphate
12. Pyrimidine
13. All of the above
14. None of the above
15. UDP
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