Overview of Archaea, Protista, and Bacteria

Prokaryotes/Bacteria Overview of Archaea, Protista, and Bacteria: Proks includes bacteria and archaea while protists are euks Archaea: oldest of the three domains and were one of the first organisms to exist on earth (are typically extremophiles thermophiles, halophiles, and methanogens) Protista: basically include any euk that is not an animal, fungi, or plant. They are typically found in aquatic/moist environments Bacteria: found in very diverse environments 3 Layers: capsule (slime mold), cell wall (different for gram positive and gram negative), and finally the plasma membrane Many bacteria use prokaryotic flagella for movement (not the same as the eukaryotic one because this one is made out of flagellin) Chemotaxis: the way that bacteria obtain nutrients by simply sensing chemicals and moving away or towards them Fimbriae/Pili: allow for colonization and resistance to flushing (not all bacterial cells have this) Nucleoid: an area for its circular DNA that is not membrane bound Inclusion Bodies: store stuff for the bacteria (like nutrients) and is important because they don’t have membrane bound organelles Bacterial Characteristics: Coccus (cocci): spherically shaped bacteria Bacillus (bacilli): rod shaped bacteria Spirochete (spirilla): squiggly shaped bacteria Gram Stain: if it stains well it turns purple (gram positive) and if it washes off and is stained by something else it turns pink (gram negative) Gram Positive Bacteria: have a plasma membrane, a thick peptidoglycan cell wall, and the capsule Gram Negative Bacteria: have an inner plasma membrane, a thin peptidoglycan cell wall, an outer plasma membrane, a lipopolysaccharide layer (LPS Layer), and the capsule Also is more likely to cause disease because it has a lot more outer membranes, further protecting the cell from antibiotic treatments Periplasmic Space: a space between the inner membrane and the cell wall Since gram positive bacteria have thick cell walls, the stain doesn’t wash off as easily as it does in the gram negative cell Bacterial Binary Fission: Binary Fission: the process by which bacteria carry out cell division and is how bacteria reproduce Origin of Replication: this is where replication enzymes being replicating its circular DNA Once DNA has been replicated and have moved to opposite sides of the cell, division of the cytoplasm begins to take place Septum: a dividing wall that forms in the middle of the cell Also, no mitotic spindle ever forms and DNA is separated as it is replicated (unlike what happens during mitosis) Genetic Recombination: leads to the creation of an organism with DNA that differs from its parent organism Conjugation: the process by which one bacterium transfers genetic material to another through direct contact (F+ is the donor bacteria and F- is the recipient bacteria) Transformation: when bacteria take up foreign genetic material from their environment Transduction: a process of genetic recombination in bacteria in which genes from a host cell (a bacterium) are incorporated into the genome of a bacterial virus (bacteriophage) and then carried to another host cell when the bacteriophage initiates another cycle of infection. In order for bacteria to perform aerobic metabolism, they sort of use their plasma membrane as an ETC in order to move electrons back and forth Aerotolerant: means that don’t need it but tolerate its environment Obligate: needs it Facultative: can use one source energy, but can also switch if need be