BSC 2010 Lecture Notes - Lecture 9: X-Ray Crystallography, Erwin Chargaff, The Double Helix

• School: University of Florida
• Department: Biology - Biological Sciences
• Course: BSC 2010
• Professor: Cuddy Katrina

Document Summary

Chapter 9 dna and its role in heredity. 9. 1 dna structure reflects its role as the genetic material. By the early 20th (cid:272)e(cid:374)tur(cid:455), a (cid:862)(cid:272)hro(cid:373)oso(cid:373)al theor(cid:455) of i(cid:374)herita(cid:374)(cid:272)e(cid:863) had (cid:271)ee(cid:374) de(cid:448)eloped, proposi(cid:374)g that me(cid:374)del"s ge(cid:374)es are o(cid:374) the (cid:272)hro(cid:373)oso(cid:373)es. Then evidence began to accumulate indicating that dna is the genetic material. Circumstantial evidence: dna is present in the cell nucleus and in chromosomes, there is twice as much in diploid cells as in haploid cells. It doubles during s phase of the cell cycle. Dna was first isolated in 1868 from white blood cell nuclei. The (cid:455)ou(cid:374)g (cid:449)iss resear(cid:272)her (cid:272)alled the fi(cid:271)rous su(cid:271)sta(cid:374)(cid:272)e (cid:862)(cid:374)u(cid:272)lei(cid:374),(cid:863) a(cid:374)d proposed that it (cid:449)as the genetic material. It was composed of c, h, o, n, and p. Dyes were developed in the early 20th century that showed color when bound to dna in dividing cells. The amount of dye that binds to dna, and thus color intensity, is related to the amount of dna present.