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Name: Nancy M.
Status: Student
Age: 20s
Location: N/A
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Date: N/A 

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 necessarily produce distinguishable individual colonies the way bacteria do. They produce masses of hyphae called mycelia.


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