Fig. 7-1 Chapter 7: DNA structure and replication

FROM GENE TO PROTEIN Replication: DNA-dependent DNA synthesis; DNA polymerase and associated proteins; DNA template, dNTPs Transcription: DNA-dependent RNA synthesis; RNA polymerase and associated proteins; DNA template, NTPs Translation: RNA-dependent polypeptide synthesis; ribosome and associated molecules; mRNA, ribosomes, aminoacyl-tRNA

Fig. 7-2 Griffith (1928): Streptococcal transformation

Fig. 7-3 Avery, MacLeod & McCarty (1944): Griffith’s “transforming principle” is DNA

Fig. 7-5

Background information available to Watson & Crick in construction of their double-helical DNA model 1.E. Chargaff’s “rule” (A=T, G=C)

Background information available to Watson & Crick in construction of their double-helical DNA model 1.E. Chargaff’s “rule” (A=T, G=C) 2.Wilkins & Franklin’s x-ray diffraction data (suggested strongly helical, probably double-helical structure)

Fig. 7-8 Major groove Minor groove

Fig. 7-8

DNA double helix is stabilized by: 1.Hydrophobic interactions among bases 2. Hydrophilic interactions of PO 4 with aqueous environment 3. Hydrogen bonds between complementary bases (A-T pair, two H bonds; G-C pair, three H bonds)

Fig Potential modes of DNA replication

Fig. 7-13

Fig ’-3’ synthesis of DNA proceeds by 3’ extension and complementary base pairing

Fig Replication fork dynamics creates polarity problems in lagging strand synthesis

Fig. 7-17

Fig Replication fork dynamics depends upon cooperative activities of a variety of proteins

Fig Chromosome replication is carried out by expansion of “bubbles”

Fig DNA synthesis creates problems at chromosome ends Ever-shortening 5’ ends

Fig Telomerase is special DNA polymerase that maintains chromosome ends Telomeres consist of high-copy number, simple sequence repeats

Fig. 7-

Human haploid genome  1 m of DNA (about 2 m DNA per somatic cell * ) (about 4.3 cm DNA per chromosome) * ~10 13 somatic cells per average human ~ 2 x m of DNA per average human (nearly 100 round trips to the sun!!)

Human haploid genome  1 m of DNA (about 2 m DNA per somatic cell * ) (about 4.3 cm DNA per chromosome) * ~10 13 somatic cells per average human ~ 2 x m of DNA per average human (nearly 100 round trips to the sun!!) Average human nucleus ~ 6 μm diameter Eukaryotic DNA is densely packaged