Nucleotide Structure and Function

Question 1

What are the three components of a nucleotide?

Answer 1

Phosphate, nitrogenous base, pentose sugar

Question 2

What are the purines and describe them?

Answer 2

Purines contain two rings in their structure. The two purines commonly found are adenine (A) and guanine (G). Both of these are found in DNA and RNA. Other purine metabolites,
not found in nucleic acids, include xanthine, hypoxanthine, and uric acid.

Question 3

What are the pyrimidines and describe them?

Answer 3

Pyrimidines have only one ring. Cytosine (C) is present in both DNA and RNA. Thymine (T) is found only in DNA, while uracil (U) is found only in RNA.

Question 4

How to remember the nitrogenous bases?

Answer 4

TCGA - that chick got ass

• T (one double bond), C (two), G (three), A (four)
• C and G are close together and have stronger, 3 H bonds
• T and C are the pyrimidines with one ring, G and A are purines with two rings

Question 5

Why is keto-enol tautermerism important for?

Answer 5

?????? Lactam and lactim

Question 6

Describe the pentose sugars of nucleotides.

Answer 6

The two pentoses found in nucleic acids are known as ribose and 2-deoxyribose. Ribose is the sugar found in RNA, while deoxyribose is found in DNA

Question 7

What are nucleosides?

Answer 7

Nucleosides are formed by covalently linking a base to the number 1 carbon of a sugar. If the sugar is ribose, then the compound formed is called a ribonucleoside. If the sugar is deoxyribose, then the compound is called a deoxyribonucleoside. The numbers identifying the carbons of the sugar are labeled with “primes” in nucleosides and nucleotides.

Question 8

What is the syn vs anti configuration of nucleosides?

Answer 8

The base is flipped from each other. In syn the base is located over the sugar and in anti is off to the side.

Question 9

What’s added to a nucleoside to form a nucleoside? Explain.

Answer 9

Nucleotides are formed when one or more phosphate groups is attached to a nucleoside.
- Ribonucleotides contain ribose, and deoxynucleotides contain deoxyribose.
-One, two, or three phosphates are most commonly attached to the 5” carbon of the sugar.
-Nucleoside di- and tri- phosphates are high-energy compounds, due to the hydrolytic energy
associated with the acid anhydride bonds.

The nomenclature for the commonly found bases, nucleosides, and nucleotides is shown in the attached table. Note that the “deoxy” part of the names deoxythymidine, dTMP, etc. is sometimes understood, and not expressly stated, since thymine is almost always found attached to deoxyribose.

Question 10

What are 7 functions of nucleotides?

Answer 10

A. Precursor for nucleic acids (NTP, dNTP)
B. Carriers of energy (ATP, GTP)
C. Carriers of specific building blocks (donates sugars in the synthesis of glycogen and glycoproteins) (UDP-Glucose)
D. Regulatory signals (second messenger mediating the response from certain hormones) (cAMP, cGMP, second messengers)
E. Methyl donor (S-Adenosylmethionine donates methyl groups in certain metabolic pathways)
F. Coenzymes (participates in oxidation reduction reactions, carries acyl groups (ex. Fatty acids) in metabolism) (NAD, FAD, NADP, Coenzyme A)
G. Drugs (5-fluorouracil - anti cancer agent, AZT - anti HIV drug)