CHAPTER 8 The Cellular Basis of Reproduction and Inheritance Modules 8.1 – 8.3

How to Make a Sea Star — With and Without Sex The life cycle of a multicellular organism includes development reproduction This sea star embryo (morula) shows one stage in the development of a fertilized egg The cluster of cells will continue to divide as development proceeds

Some organisms can also reproduce asexually This sea star is regenerating a lost arm Regeneration results from repeated cell divisions

CONNECTIONS BETWEEN CELL DIVISION AND REPRODUCTION Cell division is at the heart of the reproduction of cells and organisms Organisms can reproduce sexually or asexually

8.1 Like begets like, more or less Some organisms make exact copies of themselves, asexual reproduction Figure 8.1A

Other organisms make similar copies of themselves in a more complex process, sexual reproduction Figure 8.1B

8.2 Cells arise only from preexisting cells All cells come from cells Cellular reproduction is called cell division Cell division allows an embryo to develop into an adult It also ensures the continuity of life from one generation to the next

8.3 Prokaryotes reproduce by binary fission Prokaryotic cells divide asexually These cells possess a single chromosome, containing genes The chromosome is replicated The cell then divides into two cells, a process called binary fission Prokaryotic chromosomes Figure 8.3B

Binary fission of a prokaryotic cell Plasma membrane Prokaryotic chromosome Cell wall Duplication of chromosome and separation of copies Continued growth of the cell and movement of copies Division into two cells Figure 8.3A