1.6 Nucleic acid

Exclusion statement: the molecular structure of specific nucleotides

Nucleic acids

polymers made of nucleotide monomers

store, transmit, and express hereditary information

2 forms: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)

Components of nucleic acids: nucleotides—> polynucleotides—>nucleic acids

Nucleotides

Contains 3 parts: nitrogenous base(adenine, thymine, guanine, cytosine,or uracil), five carbon sugar(deoxyribose or ribose), and phosphate groups (in polynucleotides each monomer only has one phosphate group)

Nitrogenous base

2 types: Pyrimidines and Purines

Pyrimidines are one ring with 6 atoms: Cytosine, Thymine(only found in DNA), Uracil(only found in RNA)

Purines are one ring with 6 atoms bonded to one ring with 5 atoms: adenine and guanine

Five Carbon Sugar

A sugar is bonded to the base

in DNA the sugar is deoxyribose (OH H at the base)

in RNA the sugar is ribose (OH OH at the base)

difference in structure and function between the two

Phosphate Group

A phosphate group is added to the 5’ carbon of the sugar(which is attached to the base) to form a nucleotide

a nucleoside is a portion without a phosphate group

Polynucleotides

Phosphate groups link adjacent nucleotides

phosphodiester linkage

directionality( the measures of the phosphate and hydroxyl ends of the polynucleotides) is 5’ to 3’

the sequences of bases along the DNA or mRNA is unique for each gene

dictates AA sequence

dictates primary structure of a protein

dictates 3D structure of a protein

during nucleic acid synthesis(dehydration reaction), nucleotides are added to the 3’ end of the growing strand, resulting in the formation of covalent bonds between nucleotides

DNA

consists of two polynucleotides

forms a double helix

strands are antiparallel( 2 strands of its double helix run in opposite directions, one in 5’ to 3’ direction and the other in the 3’ to 5’ direction)

strands are antiparallel for the sugar phosphate backbone to form a stable structure and have proper DNA replication and transcription

held together by hydrogen bonds between bases

cytosine binds to guanine (C to G) with 3 hydrogen bonds

adenine binds to thymine (A to T) with 2 hydrogen bonds

the backbone is the sugar phosphate backbone

sugar is deoxyribose

more stable than RNA

double stranded

function is to store long term genetic info

found in the nucleus of a cell

RNA

single stranded polynucleotide

variable in shape due to base pairing within RNA

adenine bonds to uracil (A to U)

cytosine bonds to guanine (C to G)

sugar is ribose

more reactive than DNA

function is to be a messenger and carry genetic info

found in the nucleus, cytoplasm, and mitochondria in eukaryotic cells