Biology 1001A Chapter Notes - Chapter 9: Chromosome, Cell Nucleus, Dna Replication
27 Oct 2017
School
Department
Course
Professor
Document Summary
Genetic recombination requires: two dna molecules that differ from one another; a mechanism for bringing the dna molecules into close proximity, and a collectio(cid:374) of e(cid:374)z(cid:455)(cid:373)es to (cid:862)(cid:272)ut(cid:863), (cid:862)e(cid:454)(cid:272)ha(cid:374)ge(cid:863), a(cid:374)d (cid:862)paste(cid:863) the dna (cid:271)a(cid:272)k together. Shows two similar double helixes lying close together as the first step in recombination. Spores and zygote divide by mitosis: meiosis occurs in different places in different organismal life cycles. Red: the diploid phase of the life cycles (2n) Blue: the haploid phase of the life cycles (n) (a) meiosis in animal life cycles (b) meiosis in most plants and some fungi and algae (c) meiosis in other fungi and algae. The sporophyte is reduced and develops from a zygote within the body of the gametophyte. Vast peatlands of sphagnum gametophytes are industrially harvested in many parts of the world for fuel and horticultural use. That is, the cells now have the haploid number of chromosomes but each chromosome still has two chromatids.
