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Amoebae are microorganisms, typically haploid, that live primarily in the soil, where they phagocytose bacteria. In the laboratory, amoebae are grown on lawns of live or dead Escherichia coli on nutrient agar plates, where they can multiply indefinitely. Axenic culture of amoebae was achieved through selection of mutants capable of axenic ...
The list of organisms by chromosome count describes ploidy or numbers of chromosomes in the cells of various plants, animals, protists, and other living organisms.This number, along with the visual appearance of the chromosome, is known as the karyotype, [1] [2] [3] and can be found by looking at the chromosomes through a microscope.
The haploid number (n) refers to the total number of chromosomes found in a gamete (a sperm or egg cell produced by meiosis in preparation for sexual reproduction). Under normal conditions, the haploid number is exactly half the total number of chromosomes present in the organism's somatic cells, with one paternal and maternal copy in each ...
It can also be defined as an essentially haploid organism that carries a second copy of a part of its genome. The term is derived from the Greek, meros = part, and was originally used to describe both unstable partial diploidy, such as that which occurs briefly in recipients after mating with an Hfr strain (1), and the stable state, exemplified ...
This image shows haploid (single), diploid (double), triploid (triple), and tetraploid (quadruple) sets of chromosomes. Triploid and tetraploid chromosomes are examples of polyploidy. Polyploidy is a condition in which the cells of an organism have more than two paired sets of chromosomes.
Bacteria (/ b æ k ˈ t ɪər i ə / ⓘ; sg.: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the first life forms to appear on Earth, and are present in most of its habitats.
Sexual reproduction in early single-celled eukaryotes may have evolved from bacterial transformation, [24] or from a similar process in archaea (see below). On the other hand, bacterial conjugation is a type of direct transfer of DNA between two bacteria mediated by an external appendage called the conjugation pilus. [52]
The resulting mycelium is called a heterokaryon and is neither diploid nor haploid. The genus Neurospora also includes homothallic species in which a single haploid individual carries both mating type loci and can undergo self-fertilization leading to meiosis and sexual reproduction. Neurospora africana is an example of such a species.