Micro Ch 2

Fimbriae

filamentous proteins that are numerous and that extend from the cell to aid in adhesion and pellicle or biofilm formation

Pili

filamentous proteins that extend from the cell to serve various functions such as conjugation, transformation, and twitching motility

Periplasm

gel-like space with hydrolytic enzymes for nutrient transport and chemoreceptors to direct movement

S-layer

interlocking molecules of protein or glycoprotein that prevents osmotic lysis and acts as a semipermeable barrier

Slime layer

loose, easily deformed, sticky matrix of either polysaccharide or protein that allows prokaryotes to form biofilms and avoid dehydration

Thick cell wall

made of peptidoglycan, enables prokaryotes to withstand high pressures and hypotonic environments without lysing

Analysis of the second swab has confirmed that the causative organism is Streptococcus pyogenes, a gram-positive organism. Imagine that you are the technician looking at the Gram stain from Shelly's culture. What would you expect to see as you look through the microscope?

purple, spherical-shaped organisms arranged in chainlike formations -The purple color indicates a gram-positive organism. Recall that the purple color is due to the retention of the crystal violet-iodine (CV-I) complex in the thick peptidoglycan layer of the gram-positive organism. As the name Streptococcus implies, S. pyogenes is spherical (coccoid) in shape and remains in a chainlike formation after dividing.

Capsule

tight, sticky matrix of either polysaccharide or protein that allows prokaryotes to attach to solid surfaces and protect from desiccation; not easily washed off

In addition to flagella that allow for motility, prokaryotes have developed a number of cell surface structures that promote their survival and reproduction. These include thick cell walls, lipopolysaccharide layers, periplasm, S-layers, capsules, slime layers, fimbriae, and pili. What are their specific functions?

- cards below -

Although the archaellum is distinct from the bacterial flagellum, researchers believe that it is an example of divergent evolution and related to the type IV pilus of bacteria. What are some similarities and differences between archaella and the bacterial type IV pilus?

1. Archaella are important for swimming motility, while type IV pili are important in twitching motility. 2. Archaella have genetic similarities revealed by genomic studies. - Archaella and bacterial flagella and pili have important similarities and differences in structure and function. The number and arrangement of these structures can also be different for different microorganisms. This has been studied most thoroughly in bacteria.

Archaea and Bacteria both use whiplike structures in similar ways for locomotion, but the structures have different origins. This is an example of convergent evolution. What are some similarities and differences between archaella and bacterial flagella?

1. Archaella are made of proteins unrelated to the flagellin in bacterial flagella. 2. Archaella are powered directly by ATP, but bacterial flagella are powered by a proton motive force. 3. Archaella flagella have smaller diameters than bacterial flagella. - Archaella and bacterial flagella have important similarities and differences in structure and function. However, archaella also have important similarities and differences with the bacterial type IV pilus.

A bacterium does not continuously swim at one speed in one direction. Different arrangements and structures of flagella contribute to changes in speed and direction when necessary. How does motility relate to flagellation?

1. Bacteria with peritrichously arranged flagella change direction by changing the flagellar rotation and "tumbling." 2. Bacteria with amphitrichously arranged flagella change direction by periodically stopping to reorient themselves or by changing the flagellar rotation. 3. In general, organisms with polar flagella move more quickly than peritrichously flagellated organisms. - Motility depends on the arrangement, either polar or peritrichous, and type, either reversible or unidirectional, of flagella.

The number and arrangement of flagella can be different for different microorganisms. For instance, flagella arrangement can be described as amphitrichous, monotrichous, peritrichous, lophotrichous, or polar. Categorize the phrases and items below as instances of each arrangement.

Amphitrichous: flagella located in tufts on both ends Lophotrichous: flagella located in a tuft on one end Peritrichous: multiple flagella, all over the cell - Lophotrichous and amphitrichous arrangements are types of polar arrangement, with flagella at one or both ends of the cell, respectively. Peritrichous arrangement, on the other hand, shows flagella extending from all over the cell. - Despite the different possibilities of flagellar and archaellar arrangements, they all function primarily to propel a microorganism through its environment to reach nutrients or other similar microorganisms.

The symptoms that Shelly is experiencing result from the interactions between Streptococus pyogenes (a prokaryote) and the cells (eukaryotes) within Shelly's body. Although there are similarities between these two types of cells, there are also important differences. Drag each of the structures to the appropriate bin to indicate whether it is found in prokaryotes only, in eukaryotes only, or in both.

Eukaryote: golgi complex, mitochondria, nucleus, rough ER Prokaryote: capsule Both: cytoplasm, ribosomes, plasma membrane, flagella

How will the prescribed penicillin kill S. pyogenes that is causing Shelly's infection?

Penicillin will interfere with peptidoglycan synthesis, ultimately weakening the cell wall and leading to cellular lysis. - Penicillin will interfere with the formation of the cross-bridges in peptidoglycan. As the cell wall weakens, water will enter the cell to balance the internal/external solute concentration. The increased influx of water will disrupt the structural integrity of the cell, leading to cellular lysis and death of S. pyogenes.

What effect will the penicillin have on Shelly's cells?

The penicillin will not have any impact on Shelly's cells because it targets peptidoglycan, which is found only in bacteria. -Peptidoglycan is a compound found only in bacterial cells. Penicillin inhibits peptidoglycan synthesis and, as such, is specific to prokaryotic cells. Therefore, penicillin should kill S. pyogenes without having an impact on Shelly's cells.

Based on your understanding of the chapter material and the information in the passage, the speed of bacteria, compared with archaeans, is determined by __________.

a combination of structural, functional, and environmental factors. - There is no solid evidence that swimming speeds are solely determined by flagella width or length, the presence of flagellin protein, or the use of proton motive force versus ATP. Instead, swimming speeds are determined by a combination of factors, including microbial species, size, environmental conditions, and chemotactic factors. - Regardless of size, organisms in all three domains are capable of motility. However, the differences in the mechanisms behind their motility point to evolutionary adaptations by each domain.

Lipopolysaccharide layer

confers strength and protection and is toxic to many animals because of its lipid A component