Week 1 Flashcards
Vibrio bacterial shape
comma shaped.
Spirochetes bacterial shape
flexible, spiral-shaped bacteria that have a unique, internal flagellar arrangement
How does surface area to volume ratio affect cell growth?
As this ratio increases, the uptake of nutrients and the diffusion of these and other molecules within the cell become more efficient, which in turn facilitates a rapid growth rate
Four components of phospholipids
Ethanolamine, phosphate, glycerol, fatty acids.
Hopanoids
sterol-like molecules found in many bacterial plasma membranes. synthesized from the same precursors as steroids, and like the sterols in eukaryotic membranes, they probably stabilize the membrane
Three types of growth factors for bacteria
amino acids, purines and pyrimidines, and vitamins
Types of substances that can move across the plasma membrane via passive diffusion
O2, CO2, and water.
Three types of active transport observed in bacteria
primary active transport, secondary active transport, and group translocation
ABC transporters
ATP-binding cassette transporters, important primary active transporters
MFS transporters
Secondary active transporters include the major facilitator superfamily (MFS) proteins. MFS transporters use ion gradients, some of which are created by bacteria during their metabolic processes
distinguishing characteristic of group translocation
a molecule is chemically modified as it is
brought into the cell
PTS transport
phosphoenolpyruvate: sugar phosphotransferase system, which transports a variety of sugars while phosphorylating them, using phosphoenolpyruvate (PEP) as the phosphate donor.
siderophores
low molecular weight organic mole cules that bind ferric iron and supply it to the cell
periplasmic space
a space between the plasma membrane and the outer mem brane. It also is sometimes observed between the plasma membrane and cell wall in typical Gram-positive bacteria.
Which amino acids can be found in peptidoglycan, and what is their function?
Three of the amino acids are not found in proteins: o-glutamic acid, D-alanine, and meso-diaminopimelic acid. The presence of D-amino acids protects against degradation by most peptidases, which recognize only the L-isomers of amino acid residues
Two phyla that most gram positive bacteria belong to
Most bacteria that stain Gram positive belong to the phyla Firmicutes and Actinobacteria
Teichoic acids
polymers of glycerol or ribitol joined by phosphate groups, often covalently connected to peptidoglycan or to plasma membrane lipids. Contribute to the negative charge of bacterial cell wall.
Braun’s lipoprotein
the most abundant protein in the outer membrane, links the outermembrane to the underlying peptidoglycan cell wall;.
Three components of LPS
(1) lipid A, (2) the core polysaccharide, and (3) the 0 side chain.
lipid A region of LPS
contains two glucosamine sugar derivatives, each with three fatty acids and phosphate or pyrophosphate attached. The fatty acids of lipid A are embedded in the outer membrane, while the remainder of the LPS molecule projects from the surface
Core polysaccharide of LPS
joined to lipid A and is constructed of 10 sugars, many of them unusual in structure.
O antigen or side chain of LPS
a polysaccharide chain extend ing outward from the core. It has several peculiar sugars and varies in composition between bacterial strains
Functions of LPS in bacterial outer membranes
(1) It contributes to the negative charge on the bacterial surface because the core polysaccharide usually contains charged sugars and phosphate (figure 3.26). (2) It helps stabilize outer membrane structure because lipid A is a major constituent of the exterior leaflet of the outer membrane. (3) It helps create a permeability barrier.
Three best-studied cytoskeletal elements of bacteria
FtsZ, MreB, and CreS
FtsZ
one of the first bacterial cytoskeletal proteins identified and has since been found in most bacteria. FtsZ is a homologue of the eukaryotic protein tubulin. It forms a ring at the center of a dividing cell and is required for the formation of the septum that will separate the daughter cells
MreB
actin homologue. major function is to determine cell shape in rod-shaped cells; MreB is not found in cocci. MreB and Mbl determine cell shape by properly positioning the machin ery needed for peptidoglycan synthesis
CreS
was discovered in C. crescentus and is responsible for its curved shape (figure 3.32d). CreS is a homologue of lamin and keratin.
polyhydroxyalkonate (PHA)
How carbon is stored in storage inclusions in bacteria.
carbonic anhydrase
converts carbonic acid into C02
MIC
minimum inhibitory concentration
Legionella pneumophila characteristics
a nutritionally fastidious, aerobic, Gram-negative rod
Thus the catabolism of glucose to pyruvate can be represented by this equation.
Glucose+ 2ADP+ 2P;+ 2NAD+ ->
2 pyruvate+ 2ATP + 2NADH+ 2H+
One-step secretion systems that can span two membranes in Gram-negative bacteria
Secretion system Types I, III, IV, VI, and VII
