ASAM NUKLEAT Oleh : DR. Ir. Joni Kusnadi, MSi.

DNA structure. History: 1868 Miescher – discovered nuclein 1944 Avery – experimental evidence that DNA is constituent of genes. 1953 Watson&Crick – double helical nature of DNA. 1980 X-ray structure of more than a full turn of B-DNA.

Adapted from the Merck Manuals On-line Medical Library: http://www Adapted from Molecular Expression (http://micro.magnet.fsu.edu/cells/plantcell.html) Animal cells develop to specific cell types in different organs (differentiations). Specific cell types are for specific biological functions (e.g. production and secretion of specific hormones or enzymes).

Nucleus

Five types of bases.

Nucleotides and phosphodiester bond.

Complementarity of nucleosides – bases for double stranded helical structure

DNA base: thymine (pyrimidine) monophosphate sugar: 2’-deoxyribose  sugar: 2’-deoxyribose 5’ 4’ 1’ (5’ to 3’) 3’ 2’ 3’ linkage base:adenine (purine) 5’ linkage no 2’-hydroxyl

DNA: terminology nucleoside base phosphate(s) sugar nucleotides (nucleoside mono-, di-, and triphosphates)

DNA: structure DNA is double stranded DNA strands are antiparallel G-C pairs have 3 hydrogen bonds A-T pairs have 2 hydrogen bonds One strand is the complement of the other Major and minor grooves present different surfaces 7. Cellular DNA is almost exclusively B-DNA 8. B-DNA has ~10.5 bp/turn of the helix

RNA: terminology base sugar nucleoside Base Nucleoside (RNA) Deoxynucleoside (DNA) Adenine Adenosine Deoxyadenosine Guanine Guanosine Deoxyguanosine Cytosine Cytidine Deoxycytidine Uracil Uridine (not usually found) Thymine (not usually found) (Deoxy)thymidine base sugar nucleoside

RNA: Structure RNA can be single or double stranded G-C pairs have 3 hydrogen bonds A-U pairs have 2 hydrogen bonds Single-stranded, double-stranded, and loop RNA present different surfaces

Double helical structure of DNA. A- and B-DNA – right-handed helix, Z-DNA – left-handed helix B-DNA – fully hydrated DNA in vivo, 10 base pairs per turn of helix