Escherichia coli (commonly abbreviated E. coli) is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms (endotherms).Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans.The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2, and by preventing the establishment of pathogenic bacteria within the intestine.ost E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2, and by preventing the establishment of pathogenic bacteria within the intestine.
In flowering plants the gametophytes are very reduced in size, and are represented by the pollen and the embryo sac. The sporophyte produces spores (hence the name) by meiosis, a process also known as reduction division that reduces the number of chromosomes in each spore mother cell by half.The resulting meiospores develop into a gametophyte.n flowering plants the gametophytes are very reduced in size, and are represented by the pollen and the embryo sac. The sporophyte produces spores (hence the name) by meiosis, a process also known as reduction division that reduces the number of chromosomes in each spore mother cell by half.
Spores are haploid reproductive cells. Remember, a sporophyte is a diploid organism, so in order to produce haploid cells with half the number of chromosomes, meiosis must occur. Meiosis is a type of cell division that cuts the number of chromosomes in a cell in half. In sporophytes, it occurs in structures called sporangia (sporangium is singular). Once spores are produced in a sporangium, they are often released into the air. A single haploid spore will undergo mitosis, or cell division without a reduction in chromosome number, to become a multicellular haploid gametophyte.