The origin(s) of multicellular life on Earth is a fascinating and widely debated topic. Your question asks whether the characteristics of cells that allow multicellular organisms to evolve are found in prokaryotes or eukaryotes. It turns out that multicellular forms consist of eukaryotic cells, although it is also thought that multicellularity arose through colonial prokaryotic intermediate forms. Multicellular life evolved at least five times, leading to the distinct multicellular lineages of the green algae-land plants, red algae, fungi, animals, and brown algae. The earliest fossil evidence of multicellular organisms places their origin at about 700 million years ago (http://www.bio.ilstu.edu/armstrong/syllabi/222book/Chapt%203.htm).
Multicellular forms of life have the following characteristics:
1) they reproduce sexually
2) they have tissues and organs made of specialized cells that perform various functions, such as digesting and circulating nutrients and oxygen and getting rid of wastes
There are a number of theories about why multicellularity evolved; I will attach a number of documents here for you so you can read up on this if you are interested. Prior to the origin of eukaryotes (~ 2 billion years ago), there were only prokaryotes around, having evolved ...
4 Biology Problems
1. The integrity of the plasma membrane is essential for cellular survival. Could the immune system utilize this fact to destroy foreign cells that have invaded the body? How might cells of the immune system disrupt membranes of foreign cells? (Two hints: virtually all cells can secrete proteins, and some proteins form pores in membranes.)
2. Most cells are very small. What physical and metabolic constraints limit cell size? What problems would an enormous cell encounter? What adaptations might help a very large cell to survive?
4. Some species of bacteria that live at the surface of sediment on the bottom of lakes are facultative anaerobes; that is, they are capable of either aerobic or anaerobic respiration. How will their metabolism change during the summer when the deep water becomes anoxic (deoxygenated)? If the bacteria continue to grow at the same rate, will glycolysis increase, decrease, or remain the same after the lake becomes anoxic? Explain why.
5. Often, prokaryotic cells exist as simple unicellular organisms, but in some species, prokaryotic cells can grow together in colonies or filaments. In addition, some species, such as Cynaobacteria or Myxobacteria, demonstrate intercellular communicate , or might even produce specialized cells and structures. However, only eukaryotic cells form the bodies of multicellular organisms with complex internal specialization. Develop one or two hypotheses explaining why only eukaryotic cells are found in multicellular organisms.View Full Posting Details