BC : Nucleic acid

Nucleic acid : a biopolymer containing 3 types of monomer units

• a base (purine/pyrimidine)

• a monosaccharide (D-ribose/2-deoxy-D-ribose)

• phosphoric acid

Answer explanation

• Purine

• Pyrimidine

• Purine

• Pyrimidine

Less commmon bases

Principally but x exclusively in tRNA

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compound that consists of D-ribose or 2-deoxy-D-ribose covalently bonded to a nucleobase by β-N-glycosidic bond

• - lack phosphate grp

Answer explanation

a nucleoside in which a mlcl of phosphoric acid is esterified w/ an -OH of monosaccharides (3'-OH or 5'-OH)

Answer explanation

name based on parent nucleoside w/ suffix monophosphate

.... leads to nucleic acids.

• - Linkage is repeated

• - 3', 5'-phosphodiester bond

• Polymerization

• Condensation

• - sequence of bases along pentose-phosphodiester backbone of a DNA mlcl

• - base sequence read from 5'end to 3'end

• DNA 1° structure

• DNA 2° structure

• DNA 3° structure

Answer explanation

• - ordered arrangement of nucleic acid strands

• - double helix : 2 antiparallel polynucleotide strands coiled in right-handed manner about same axis

• DNA 1° structure

• DNA 2° structure

• DNA 3° structure

Answer explanation

• - double helix model proposed by James Watson & Francis Crick

• - structure based on X-ray crystallography

• DNA 3° structure

• • 3D arrangement of all atoms of a nucleic acid

• commonly referred as supercoiling : further coiling & twisting of DNA helix

• • Topoisomerases

  Class I : cut phosphodiester backbone of 1 strand, pass end thru & reseal

  Class II : cut both strands, pass some of remaining DNA helix btwn cut strands & reseal

• • circular DNA : dsDNA which 5' & 3' ends of each stand are joined by phosphodiester bonds

• DNA gyrase : bacterial topoisomerase

Answer explanation