Presentation on theme: "+ Bacteria and Archaea. + Cell surface markers of prokaryotes Most bacteria contain peptidoglycan in their cell walls, which is a polymer of modified."— Presentation transcript:
+ Cell surface markers of prokaryotes Most bacteria contain peptidoglycan in their cell walls, which is a polymer of modified sugars linked by polypeptides. Peptidoglycan is unique to eubacteria. Although Archaeal cells have polysaccharides and proteins, but not like peptidoglycan.
+ Gram Staining: Used to determine amount of peptidoglycan in the cell wall Gram Positive prokaryotes have have relatively high amounts of peptidoglycan. Gram negative prokaryotes have low amounts of peptidoglycan in their cell walls.
+ Significance of gram + and gram - bacteria Used to help doctors determine the nature of infection. The use of antibiotics when you are sick is very situational. Some antibiotics are only effective versus certain bacteria. http://en.wikipedia.org/wiki/L ist_of_antibiotics http://en.wikipedia.org/wiki/L ist_of_antibiotics
+ Capsules and endospores: ways of withstanding harsh conditions The capsule of a prokaryote typically a sticky layer of polysaccharide or protein. Endospores are dormant, tough, and non-reproductive structure produced by certain bacteria. CapsulesEndospores
+ Fimbriae and the pili Fimbriae are appendages that act like anchors that hold the bacterium to its substrate Pili are similar to fimbriae, only they can be responsible for passing DNA to one another (nonsexual).
+ Means of Motility Some bacteria undergo taxis, or the movement towards a stimulus. They accomplish this by means of a flagellum at most parts.
+ Internal organization and DNA Bacteria lack membrane bound organelles. Their DNA is located in a region called a nucleoid, which is a region where the DNA is located. THIS IS NOT A NUCLEUS!!!!!! Some bacteria have what is called a plasmid, which is a small ring that carries a few genes (for transformation). In terms of reproduction, bacteria undergo binary fission, where the cell divides into two cells.
+ Rapid Reproduction and Mutation Figure 27.10 Transformation is the process by which one strain of bacteria is changed by a gene or genes from another bacteria. Transduction: 27.11
+ Conjugation Conjugation is the passing of information across a pilus from one species to another. The piece of a piece of DNA called an F factor (fertility). R plasmids can confer antibiotic resistance to another bacterium. (we will be doing this later in the semester) Figure 27.13b
+ Role of oxygen and nitrogen in metabolism Obligate aerobes: need O 2 to undergo respiration Obligate anaerobes: Need to exclusively be away from O 2, as it is poisonous to them. Undergo anaerobic respiration. Facultative anaerobes: undergo aerobic respiration, but if O2 is absent, the bacteria can undergo fermentation. Nitrogen in the atmosphere is useless as is to humans. Some methanogens (Archaea) and cyanobacteria can affix to atmospheric nitrogen into ammonia. The fixed nitrogen can then be made into various amino acids.
+ Metabolic Cooperation Some cells in a filament (a chain) can be specialized to do certain things that other cells cannot do. A heterocyst is a good example because it allows for cells to affix nitrogen whilst other cells continue to undergo photosynthesis. Biofilms: