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The algae contain chloroplasts that are similar in structure to cyanobacteria. Chloroplasts contain circular DNA like that in cyanobacteria and are interpreted as representing reduced endosymbiotic cyanobacteria. However, the exact origin of the chloroplasts is different among separate lineages of algae, reflecting their acquisition during ...
Structure of a typical animal cell Structure of a typical plant cell. Plants, animals, fungi, slime moulds, protozoa, and algae are all eukaryotic. These cells are about fifteen times wider than a typical prokaryote and can be as much as a thousand times greater in volume.
The cells of plants, algae, fungi and most chromalveolates, but not animals, are surrounded by a cell wall. This is a layer outside the cell membrane, providing the cell with structural support, protection, and a filtering mechanism. The cell wall also prevents over-expansion when water enters the cell. [45]
Most eukaryotic algae contain on average about 0.54 pg DNA/cell, whereas estimates of dinoflagellate DNA content range from 3–250 pg/cell, [32] corresponding to roughly 3000–215 000 Mb (in comparison, the haploid human genome is 3180 Mb and hexaploid Triticum wheat is 16 000 Mb).
Think of the cell wall as a wicker basket in which a balloon has been inflated so that it exerts pressure from the inside. Such a basket is very rigid and resistant to mechanical damage. Thus does the prokaryote cell (and eukaryotic cell that possesses a cell wall) gain strength from a flexible plasma membrane pressing against a rigid cell wall ...
Haploid algal cells (containing only one copy of their DNA) can fuse with other haploid cells to form diploid zygotes. When filamentous algae do this, they form bridges between cells, and leave empty cell walls behind that can be easily distinguished under the light microscope. This process is called conjugation and occurs for example in Spirogyra.
The unique combination of host cell and complex plastid results in cells with four genomes: two prokaryotic genomes (mitochondrion and plastid of the red or green algae) and two eukaryotic genomes (nucleus of host cell and nucleomorph). The model cryptomonad Guillardia theta became an important focus for scientists studying nucleomorphs. Its ...
Comparatively, in the laboratory, most cultured cells—which are large compared to normal plant cells—produce very long and abundant stromules that extend to the cell periphery. In 2014, evidence was found of the possible loss of plastid genome in Rafflesia lagascae , a non-photosynthetic parasitic flowering plant, and in Polytomella , a ...