DNA Nucleic acids polymers responsible for the storage

DNA

Nucleic acids – polymers responsible for the storage, expression, and transmission of genetic information • Includes: DNA and RNA

Nucleotides – building blocks of DNA, made of 3 parts Phosphate 5 carbon sugar Nitrogenous base

5 carbon sugar: • in RNA = ribose, in DNA = deoxyribose

Nitrogenous bases: • Purines - double ring • Adenine (A) • Guanine (G) • Pyrimidines – single ring • Thymine (T) • Cytosine (C) • Uracil (U)

Strand – nucleotides are attached to each other

Backbone – phosphates and sugars • Shows directionality, each phosphate bonds to the 5’ carbon in one nucleotide and the 3’ carbon in the next nucleotide • 5’ – TACG – 3’

Center rungs – made up of the nitrogenous bases that are linked to each other with weak hydrogen bonds, specific sequences allow them to store and transmit information

EXPERIMENTS

Rosalind Franklin and Maurice Wilkins • X-ray diffraction suggested a double helix pattern

Erwin Chargaff • showed that each sample of DNA contained similar amounts of A and T and similar amounts of C and G

James Watson and Francis Crick • created ball and stick models to show a double helix

DNA – The Secret of Life • https: //www. youtube. com/watch? v=rw 7 XU 7 dur. G 4

DNA Key structures • Two strands of DNA form a double helix

DNA Key structures • Bases in opposite strands form hydrogen bonds according to the AT/CG rule

DNA Key structures • The two strands are complementary – can predict the sequence of one strand if you know the other strand

DNA Key structures • The two strands are antiparallel – one strands runs the 5’ to 3’ direction while the other runs the 3’ to 5’ direction