Bio 261: Chapter 2 Study Guide || with Complete Solutions.

How do cocci and rods differ in morphology? Give an example of a bacteria with each morphology. correct answers Cocci are spherical or ovoid (ex: Streptococcus or Staphylococcus) while rods/bacillus are cylindrical/longer than it is wide (ex: Bacilli or Salmonella). Using a microscope, could you differentiate a coccus from a spirillum? A pathogen from a nonpathogen? correct answers Yes, a coccus is spherical while a spirillum is curved or spiral. No regarding the pathogens from nonpathogens. Why is the cytoplasmic membrane a good permeability barrier? correct answers The hydrophobic/hydrophilic regions make it highly selective and most polar and charged molecules cannot pass unless carried by transport proteins. Similarities between the membrane lipids of Bacteria and Archaea correct answers phospholipid bilayer containing embedded proteins, contain glycerol, polar head groups with functional groups Bacteria membrane lipid correct answers 8-10 nm wide, some are strengthened by hopanoids, and contain integral and peripheral proteins, have ester linkages, consists of fatty acids Archaea membrane lipid correct answers contain ether linkages, have isoprene instead of fatty acids, constructed from either phosphoglycerol diethers or diphosphoglycerol tetraethers Describe the major functions of the cytoplasmic membrane. correct answers It is a permeability barrier, meaning it transports nutrients inside the cell and pushes waste products out. Anchors several proteins that catalyze many important cell functions. The cytoplasmic membrane of Bacteria and Archaea play a major role in energy conservation and consumption. Why do bacterial cells need cell walls? Do all bacteria have cell walls? correct answers To protect against cell lysis (bursting of a cell) and to keep shape and rigidity on the cell; no. Why is peptidoglycan such a strong molecule? correct answers It is what the cell wall of bacteria is made of and what gives it it's strength. It is rigid and typically composed of repeating units of modified glucose (N-acetylglucosamine and N-acetylmuramic acid) in Beta-1,4 linkages. What do the enzyme lysozyme and the antibiotic penicillin have in common? correct answers They are both molecules that destroy peptidoglycan. Describe the major chemical components in the outer membrane of gram-negative bacteria. correct answers It is not made solely of phospholipid and protein like the cytoplasmic membrane. Instead, it contains polysaccharide, and the lipid and polysaccharide are linked to form a complex. The outer membrane is often called lipopolysaccharide (LPS). The polysaccharide portion of LPS consists of two components- the core polysaccharide and the O-specific polysaccharide.