Interphase: Add mushrooms to represent organelles and a ring of pepperoni to make a nuclear membrane. Strips of peppers would represent the DNA inside the nucleus. To model the end of interphase, double the number of mushrooms on the pizza to indicate the copying of the organelles. Double the number of peppers inside the nucleus to represent the replication of DNA.
Prophase: Pair strips of pepper inside the nucleus to show the formation of chromosome pairs. Strips of aluminum foil would represent spindle fibers.
Metaphase: Line up the pair of peppers along the middle of the pizza. Removing the pepperoni would show the breakdown of the nuclear membrane.
Anaphase: Split up the pairs of peppers, and show the spindle fibers, made of aluminum foil, pulling them to either side of the cell.
Telophase: Make two new nuclear membranes around the pepper strips using pepperoni. Separate the pairs of peppers to show the chromosomes unwinding.
Cytokinesis: Cut the pizza across the middle to show the cell dividing into two daughter cells.
<span>A mature sporophyte produces spores by meiosis, a process which reduces the number of chromosomes to half, from 2n to n. Because meiosis is a key step in the alternation of generations, it is likely that meiosis has a fundamental adaptive function. The nature of this function is still unresolved (see Meiosis), but the two main ideas are that meiosis is adaptive because it facilitates repair of DNA damages and/or that it generates genetic variation.
The haploid spores germinate and grow into a haploid gametophyte. At maturity, the gametophyte produces gametes by mitosis, which does not alter the number of chromosomes. Two gametes (originating from different organisms of the same species or from the same organism) fuse to produce a zygote, which develops into a diploid sporophyte.</span>
