Nucliec Acids

Polymer

-Polynucleotides or Nucliec Acids (DNA or RNA)

Monomers

Nucleotides

Bond

Covalent: Phosphodiester Bond

3 subcomponents of a Nucleic Acid Monomer:

-Pentose Sugar (2 types)

-Nitrogenous Base (5 Types)

-Phosphate Group (at least 1)

Pentose

-A term given to monosaccharide with 5 carbons: 4 will be carbons and 1 will be an oxygen

-2 types: Ribose and Deoxyribose

Ribose: Has a OH group on the 2’C - found in RNA

Deoxyribose: Only has H on the 2’C - found in DNA

Nitrogenous Base

-Nitrogenous Base = nitrogen rich

-Cystosin (C), Thymine (T), Uracil (U), Adenine (A), Guanine (C)

-2 Different Group: Pyrimidine and Purines

-Purines = 2 rings with 9 atoms

-Pyrimidines = 1 ring with 6 atoms

Cytosine

-Pyrimidine

-Has an Amino Group

-Found in both DNA and RNA

-No methyl group

-Double bounded N within ring

Thymine

-Pyrimidine

-Two Carbonyl Groups

-Methyl Group

-Found in DNA

Uracil

-Pyrimidine

-Two carbonyls

-Lacks methyl group

-Found in RNA

Adenine

-Purine

-Have an amino group

-Has a total of 3 N double bonds

-Found in DNA and RNA

Guanine

-Purine

-Carbonyl group

-Amino Group

-Found in DNA and RNA

Nucleotide Nomenclature

Nitrogenous Base = 1,2,3,4,5,

Carbons of Pentose Sugar = 1’,2’, 3’. 4’, 5’

• Nitrogenous Base is attached to 1’ Carbon

• Phosphate group is attached to 5’C

-Linkage between phosphate and carbon is a covalent bond

Name = nitrogenous base, sugar, and how many phosphates

• Nitrogenous Base = Adenine

• Sugar = Ribose

• 3 Phosphates (TRI)

Nucleoside

Sugar and Nitrogenous Base only

Directional Synthesis in Nucleic Acid

When nucliec acids are synthesized in cells, new nucleotides are always going to be added to the 3’ Hydroxyl Group of the pentose

• 3’ has a free hydroxyl group to react w/carbons so that the hydroxyl group get kicked out

• 5’ has a free phosphate group

3’ carbon is where the phosphate of another nucleotide ends up attaching, the phosphate is attached to the 5’ carbon of that nucleotide, so the phosphodiester bond is between 3’ and 5’ carbon of 2 different nucleotides

DNA Structure

Double helix

Sides of the ladder are made of the sugar-phosphate backbone (deoxyribose and phosphate group)

rungs of the ladder are made up of nitrogenous base pairs (held together through HYDROGEN BONDS: a purine with a pyrimidine

Double Helix is antiparallel: goes from: 5’ to 3’ and 3’ to 5’

DNA Base Pairing

• Adenine (A) ↔ Thymine (T) → 2 hydrogen bonds

• Guanine (G) ↔ Cytosine (C) → 3 hydrogen bonds

RNA Base Pairing

• Adenine (A) ↔ Uracil (U) → 2 hydrogen bonds

• Guanine (G) ↔ Cytosine (C) → 3 hydrogen bonds

Directional Synthesis

-The additional nucleotide must be added to the growing polypeptide at a specific carbon (specific position on the nucleotide)

-The 3’ carbon of one nucleotide holds a hydroxyl which is kicked out by a phosphate group of another nucleotide

-Since the new groups are always added to this 3’ position, the polynucleotide is said to be built in the 5’ —> 3’ direction