Bread Mold Life Cycle
Name: Nancy M.
In the common bread-mold life cycle, what do the plus
and minus signs mean?
Also why aren't bread molds streaked for isolation like bacteria are?
Molds do not have male and female members per se. They have two phases to
their life cycles, an asexual phase which reproduces by mitosis and a sexual
phase. In this phase the haploid hyphae ( the fuzzy stuff) grow toward each
other and fuse producing a diploid zygospore that can withstand harsh
conditions. When the zygospore germinates and undergoes meiosis it develops
into a sporangium full of sproangiospores which can pop spreading the spores
around again. Some are the + strain and some are the - strain and the cycle
begins again. We do not streak for isolation because molds do not
produce distinguishable individual colonies the way bacteria do. They
produce masses of hyphae called mycelia.
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Update: June 2012