Cellular Microbes

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  1. What are the two broad categories of cellular microbes?
    Prokaryotic: Characterised as being smaller, simpler and lacking internal membranes.

    Eurkaryotic: Characterised as being larger, more complex and having internal membranes.
  2. What is the structure of the procaryotic cell?
    Procaryotic cells are simple and consist of a genome, cytoplasm, plasmids and ribosomes all contained within a cell wall. The cell exterior may feature small appendages called pili and/or a large appendage called the flagellum, used to propel the cell.
  3. What is the cell membrane?
    The prokaryotic plasma membrane is an organised structure designed to contain and protect the cytoplasm and interior components of the cell. It is generally constructed of a phospholipid bilayer, as well as proteins.
  4. What is the structure of the bacterial chromosome?
    The bacterial chromosome is a long, highly coiled DNA molecule that is not contained within a nucleus.
  5. What is a plasmid?
    A plasmid is a DNA molecule contained within a cell but separate from a chromosome. They are capable of independent replication and in bacteria can be passed between organisms in order to share genes.
  6. What is the cytoplasm?
    The cytoplasm the substance on the interior of the cell. It consists of cell components as well as cytosol; the medium in which the components are suspended. Cytosol is mostly water but also consists of a vast number of other molecules such as proteins, carbohydrates, lipids, enzymes, salts and ions. In prokaryotes the cytoplasm is the site of most metabolism, rather than the mitochondia, ribosomes or others structures of eukaryotic cells.
  7. What is a ribosome?
    Ribosomes are large molecules that are the site of primary protein synthesis; they take mRNA and link together amino acids to form peptides chains and eventually, proteins.
  8. What is the cell wall?
    Lying over the plasma membrane, the cell wall is another layer in a procaryote's protective barrier. It is made out of peptidoglycan, a polymer consisting of sugars and amino acids. Peptidoglycan is peculiar to bacteria and as such is useful for antibiotics targeting gram positive bacteria, which contain thick peptidoglycan walls.
  9. What is glycocalyx?
    Glycocalyx means something along the lines of "sugar coat," it refers to the material that is found on the outside of prokaryotic - among other - cells. It is the component creating the capsule and slime layer.
  10. What is the capsule?
    The capsule is a well ordered structure composed of glycocalyx and attached to the cell wall. The capsules enables adhesion to surfaces and protects the cell. Encapsulated bacteria are also somewhat more resistant to phagocytosis.
  11. What is a slime layer?
    A slime layer is a disorganised layer of glycocalyx that facilitates movement and prevents dehydration of cells. It is sometimes the broken down form of a cell's capsule.
  12. What are flagella?
    Flagella are long, tail-like appendages that serve to propel cells, making them "motile." A cell may have multiple flagella in one of a variety of arrangements. Flagella may also serve some sensory purpose because of their reactions to certain chemicals or temperature outside the cell.
  13. What are pili?
    Pili are appendages that originate in the cytoplasm end extend out of the exterior of the cell. They allow the attachment of bacteria to surfaces and the sex pilus allows the transfer of plasmids between prokaryotes.
  14. What is an endospore?
    An endospore is a structure produced by prokaryotes in times of stress, containing a copy of the genome and some cytoplasm. It is somewhat like a black-box, containing the information needed to create a new bacteria inside of an incredibly tough coating. When it finds a suitable environment, an endospore "germinates."
  15. What is the structure of the surface structure of gram negative bacteria?
    Gram negative bacteria, at their most proximal layer, contain a plasma membrane. This is made of a phospholipid bilayer and proteins. Attached by proteins through the periplasmic space is the cell wall, a thin layer of peptidoglycan that attaches through another periplasmic space onto another outer membrane, also a phospholipid bilayer.
  16. What is the structure of the gram positive surface structure?
    The gram positive surface structure consists of a plasma membrane at its most proximal. This membrane is composed of a phospholipid bilayer, as well as proteins. Attached to this through the periplasmic space is the cell wall, itself composed of a thick layer of peptidoglycans.
  17. How do prokaryotic cells reproduce?
    Through a process called binary fission. The genome is copied, then the surface structure is split to fully enclose the two genomes, as well as the cytoplasm, ribosomes and plasmids to accompany them.

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Cellular Microbes
2013-03-24 02:19:45
Cellular Microbes

Prokaryotic and Eurkaryotic. Bacteria, archea, protozoa, fungi, yeasts.
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