Chap 9 Nucleotides and Nucleosides nomenclature

Nucleotide composition (RECAP)

Composed of 3 parts:

- phosphate group

- sugar (pentose 5 carbon molecule)

- nitrogenous base

nucleosides composition (RECAP)

Composed of 2 parts

- nitrogenous base

- sugar (pentose 5 carbon molecule)

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NO PHOSPHATE GROUP

types pentose sugar in nucleotides

Ribose = RNA

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Deoxyribose = DNA

Ribose

REMEMBER HOW TO DRAW IT:

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Basic rule of thumb:

- if 2' is OH its ribose (RNA)

Deoxyribose

REMEMBER HOW TO DRAW IT:

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Basic rule of thumb:

- if 2' is H it deoxyribose (DNA

nucleotide structures

mostly tetrahedron structure (4 triangles) with either:

- repeating unit of DNA or...

- repeating unit of RNA

phosphate group/ phosphodiester bonds

attaches conveniently to either the 5' or 3' of a ribose or deoxyribose nucleotide

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- the strand has directionality 5' to 3'

- in a strand, all sugar molecules are oriented in the same direction

- the phosphate and sugar molecules form the backbone of the nucleic acid strand

- the bases project from the backbone

Nitrogenous bases

- purines

- pyrimidines

Purines

2 fused rings (penta + hexa)

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EXAMPLES:

- adenine (A)

- guanine (G)

Adenine (A)

type of purine (recognize it)

Guanine (G)

type of purine (recognize it)

Pyrimidines

1 single fused ring (hexa)

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EXAMPLES:

- Thymine (T)

- Cytosine (C)

- Unicil (U)

Thymine

type of pyrimidine (recognize it)

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Found mostly in DNA

Cytosine

type of pyrimidine (recognize it)

Uricil

type of pyrimidine (recognize it)

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Found mostly in RNA

terminology of nitrogenous bases + sugars

Basic rule of thumb: Ribose

(Purine or pyrimidines) + ribose = prefix of compound with o and suffix -sine

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Basic rule of thumb: Deoxyribose

(Purine or pyrimidines) + deoxyribose = prefix deoxy- , prefix of compound with o, suffix -sine

ribose examples/ Nucleoside examples

adenine + ribose = adenosine

guanine + ribose = guanosine

Deoxyribose examples/ Nucleoside examples

adenine + deoxyribose = deoxyadenosine

guanine + deoxyribose = deoxyguanosine

terminology of nitrogenous bases + sugars + phosphate

Basic rule of thumb:

The same rules apply in terms of the nitrogenous base but just add the amount of phosphates based on its prefix:

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- mono = 1

- di = 2

- tri = 3

- tetra = 4

- penta = 5

- hexa = 6

- hepta = 7

- octa = 8

- nona = 9

- deca = 10

ribose with phosphate (examples) / nucleotide examples

adenine + ribose + 1 phosphate = adenosine monophosphate (AMP)

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adenine + ribose + 2 phosphate = adenosine diphosphate (ADP)

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adenine + ribose + 3 phosphate = adenosine triphosphate (ATP)

how to determine if a structure is DNA or RNA

Basic rule of thumb:

1: Check 2' on the sugar

(RECAP: OH = ribose , H = deoxyribose)

2: If the structure is unclear check the nitrogenous base

nitrogenous base distinction between DNA and RNA

DNA BASE:

- G,C,A,T = (G CAT)

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RNA BASE:

- G,C,A,U = (G CAU)