DNA replicated in 5’ to 3’ direction (5’->3’). DNA polymerase requires template strand (guide), primer strand with free 3’OH group, activated substrates/precursors= nucleoside triphosphates DNA synthesis by DNA polymerases fig _ Table _ġ. nalidixic acid) and fluoroquinolones (such as ciprofloxacin) and novobiocin inhibit bacterial gyrase and interfere with DNA replication/transcription see pĬ. bacterial gyrase is involved in supercoiling/relief of supercoiling of DNA play an important role in the behavior of DNA in the cell.“ Brock Biology of Microorganisms 8th edition p 185 ) Because coiling is necessary for packing DNA into the confines of a cell and relaxing is necessary so DNA can be replicated (and transcribed), these two complementary processes. “Through the action of topoisomerases, the DNA molecule can be alternately coiled and relaxed. Type II= Bacterial Gyrase: introduces negative supercoils Topoisomerases Enzymes which “supercoil” DNA or relieve supercoiling different types of toposiomerases in E. 1 copy of chromosomes=“haploid cells” (most human cells have 2 copies of linear chromosomes and are called “diploid cells” see “eukaryotic chromosomes). Prokaryotic chromosomes see figure Most bacteria have a single circular chromosome. C1' covalently linked to nitrogenous base.ħ. complementary base pairing permits the precise replication of DNAĦ. Chagraff’s rules: amount of A=T and amount of C=G this is because of complementary base-pairing rules purines (2 rings)= adenine (A) and guanine (G) pyrimidines (1 ring)= thymine (T) and cytosine (C)ī. Sugar=deoxyribose, phosphate, nitrogenous baseĪ. Strong outer “sugar-phosphate” backbone covalent phosphodiester bonds link nucleotidesĤ. Two strands held together by hydrogen bonds between complementary bases inside helixĢ. DNA Structure: figure 8.3 Double stranded (2 strands of DNA), helical “double helix”, antiparallelġ. DNA will be replicated and passed on to “daughter cells”ī. Central Dogma of genetics/info flow in cells -Foundation Figure: Flow of Genetic Info p 1. Genetic code: 1 to 1 relationship between a codon (specific sequence of 3 bases) and 1 amino acid. Function: DNA base sequence encodes information for amino acid sequence of proteins.
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