2. Nucleotides and Nucleic Acids

Pyrimidine base

6 membered heterocyclic ring with 2 N

Common pyrimidines

Uracil, thymine, and cytosine

Uracil

Pyrimidine base with two O and two NH. Found in RNA

Thymine

Pyrimidine base with two O, two NH, and a CH₃. Found in DNA

Cytosine

Pyrimidine base with one O, one N, one NH, one NH₂

Purine base

6 membered and 5 membered heterocyclic rings with N on 1, 3, 7, and NH on 9

Adenine

Purine base with no O

Guanine

Purine base with an O

Lone pairs in resonance can accept hydrogen bonds. True or false?

False, the electrons are delocalized

Is the following lone pair involved in resonance? Can it accept hydrogen bonds?

Yes, no it can only donate.

Is the following lone pair involved in resonance? Can it accept hydrogen bonds?

No, yes it can accept.

Is the following lone pair involved in resonance? Can it accept hydrogen bonds?

Yes, no it can only donate two.

Is the following lone pair involved in resonance? Can it accept hydrogen bonds?

Yes, no it can only donate two.

Compare RNA vs DNA

RNA: polymer of G, A, C, U, ribose sugar, single stranded

DNA: polymer of G, A, C, T, deoxyribose sugar, double stranded

Compare structure of deoxyribose compared to ribose.

Deoxyribose is missing an O at C2’

Nucleoside

Nitrogenous base attached to a pentose, 5C sugar.

How does the numbering of bases differ from sugars.

Sugars are numbered with primes, bases only use numbers

When a nucleoside is formed what parts of the sugar and nitrogen base are lost?

-OH lost from C1’ of sugar and H lost from N1 of base

In nucleoside formation, where is the sugar attached for pyrimidines vs purines.

N1 for pyrimidines N9 in purines

When naming nucleosides, how are purines named?

-ine becomes -osine (adenosine, guanosine)

When naming nucleosides, how are pyrimidines named?

ending is changed to -idine (cytidine, thymidine, uridine)

Formation of phosphoester bond

phosphate + hydroxyl group

Nucleotide

Nucleoside + phosphate

How are nucleotides named

Nucleoside name + # of phosphates

Where doe the phosphates typically attach to nucleosides? Where else can they attach.

C5’. Can also attach to C2’ or C3’ (would need to be specified in the naming)

CONTINUE nucleic acids