Nucleic Acids 3

Flashcards about nucleic acids

Nucleic Acids

The biochemistry of DNA and RNA; includes structures of DNA and RNA.

A form DNA

Right handed, ~26 Å diameter, 11 base pairs per helical turn, 2.6 Å helix rise per base pair, 20° base tilt, C-3' endo sugar pucker, Anti glycosyl bond conformation

B form DNA

Right handed, ~20 Å diameter, 10.5 base pairs per helical turn, 3.4 Å helix rise per base pair, 6° base tilt, C-2' endo sugar pucker, Anti glycosyl bond conformation

Z form DNA

Left handed, ~18 Å diameter, 12 base pairs per helical turn, 3.7 Å helix rise per base pair, 7° base tilt, C-2' endo for pyrimidines; C-3' endo for purines sugar pucker, Anti for pyrimidines; syn for purines glycosyl bond conformation

Triple helical DNA (triplexes)

DNA structure with three strands.

Quadruplexes (tetraplexes)

DNA structure with four strands.

Palindromes

Words or phrases that are the same when read backward or forward.

Hairpins and cruciforms

Secondary structures formed in DNA or RNA that contain palindromes or repeats.

Internal loop

A loop within an RNA molecule where the strand is not paired.

Bulge

Unpaired nucleotide bases in a secondary structure.

RNA secondary structures

RNA molecules demonstrating complex secondary structures.

RNA in 3D

Illustrations of RNA in three-dimensional configurations.

DNA and RNA Denaturation

Process where covalent bonds remain intact. Genetic code remains intact but hydrogen bonds between strands are broken. Two strands separate. Base stacking is lost and UV absorbance increases

Annealing

Reversible reformation of double-stranded DNA from single strands through base pairing.

Tm

Temperature at which 50% of the DNA is denatured.

Dimerization of pyrimidines

Caused by UV light. May be the main mechanism for skin cancers.

Ionizing Radiation

radiation causes ring opening and strand breaking of nucleic acids

Thymine dimers

Structural distortions in DNA caused by the formation of pyrimidine dimers.

Damage to nucleic acids

Mutations and Accumulation of mutations.