What types of proteins are embedded in the bacterial cytoplasmic membrane?
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Integral membrane proteins and peripheral membrane proteins.
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What types of proteins are embedded in the bacterial cytoplasmic membrane?
Integral membrane proteins and peripheral membrane proteins.
What direction does the flagellar motor rotate during a 'run'?
Counterclockwise.
What are the small cells found in open oceans called?
Ultramicrobacteria.
What is a key advantage of being small in cellular biology?
Higher surface area relative to cell volume (higher S/V ratio).
What organism is best studied for chemotaxis?
E. coli.
What is the main component of the flagellum filament?
Flagellin.
What is taxis in biological terms?
Directed movement in response to chemical or physical gradients.
What is the shape of flagella?
Helical.
What is the size range for prokaryotes?
0.2 μm to >700 μm in diameter.
What does morphology refer to in the context of cells?
Cell shape.
What is the typical width of most cultured rod-shaped bacteria?
Between 0.5 and 4.0 μm.
What are capsules and slime layers considered in relation to the cell wall?
They are not considered part of the cell wall because they do not confer significant structural strength.
What are the two main components of the flagellum motor?
The rotor and the stator.
What are the two types of flagellation in prokaryotic cells?
Peritrichous and polar flagellation.
Name a very large prokaryote.
Epulopiscium fishelsoni.
Which bacteria are linked to gastrointestinal symptoms due to LPS?
Salmonella, Shigella, and Escherichia.
Are peptidoglycan cell walls present in Archaea or Eukarya?
No, they are not present in the cell walls of Archaea or Eukarya.
How does a higher S/V ratio benefit small cells?
It supports greater nutrient and waste product exchange per unit cell volume.
What is chemotaxis in bacteria?
A movement response to chemical stimuli.
How are species of bacteria classified based on Gram stain?
Into two groups: Gram-positive and Gram-negative.
What are the different arrangements of flagella?
Polar, lophotrichous, amphitrichous, peritrichous.
How are integral membrane proteins characterized?
They are significantly embedded in the membrane.
What does the rotor of the flagellum consist of?
The central rod and the L, P, C, and MS rings.
What is the shape of rod/bacillus cells?
Cylindrical.
What is the role of lipid A in LPS?
It can be toxic to animals and comprises the endotoxin complex.
What does the rotor of the flagellum consist of?
The central rod and the L, P, MS, C rings.
How can capsules vary in their physical properties?
They may be thick or thin, rigid or flexible.
What is the function of the stator in the flagellum motor?
The stator consists of Mot proteins that surround the rotor and generate torque.
What is polar flagellation?
Flagella are located at one or both ends of the cell.
How does peritrichous flagellation affect movement?
It allows for more versatile movement in various directions.
How does polar flagellation affect movement?
It typically results in a more directed movement.
What are flagella and archaella?
Structures that assist in swimming in Bacteria and Archaea, respectively.
Does morphology predict the physiology of a prokaryotic cell?
No, morphology typically does not predict physiology, ecology, phylogeny, or other properties.
Do smaller cells always grow faster than larger cells?
Not necessarily; for example, Pelagibacter ubique grows much slower than Ruegeria pomeroyi.
How do polarly flagellated bacteria differ from peritrichous cells in chemotaxis?
They are similar but not identical.
What factors are discussed in relation to small cells?
Surface-to-volume ratios, growth rates, and evolution.
What is optimized for nutrient uptake in prokaryotic cells?
Small cells with a high surface-to-volume ratio, such as appendaged cells.
What is another name for the Gram-negative cell wall?
Cell envelope.
What materials are capsules and slime layers made of?
Polysaccharides or protein layers.
What does the periplasm house?
Many extracellular proteins.
What is peritrichous flagellation?
Flagella are distributed all over the surface of the cell.
How do transport proteins function in relation to solutes?
They accumulate solutes against the concentration gradient.
What is the main function of the cytoplasmic membrane?
Selective permeability.
What are Fli proteins responsible for in gram-negative bacteria?
They act as a motor switch, reversing the direction of rotation of the flagella.
What may influence the morphology of prokaryotic cells?
Selective forces may be involved in setting the morphology.
What is the shape of coccus cells?
Spherical or ovoid.
How does gliding motility compare to swimming?
It is slower and smoother than swimming.
What is the typical length of most cultured rod-shaped bacteria?
Less than 15 μm long.
How are peripheral membrane proteins characterized?
They are loosely attached to the membrane.
What happens to some bacteria like Rhodobacter during chemotaxis?
They stop and are affected by Brownian motion.
What describes the shape of spirillum cells?
Curved or spiral.
What is Brownian motion?
The random motion of particles suspended in a liquid medium.
What types of unusual shapes can prokaryotic cells have?
Appendaged bacteria and filamentous bacteria.
What are fimbriae?
Filamentous protein structures that enable organisms to stick to surfaces or form pellicles.
What is the primary function of peptidoglycan in bacterial cell walls?
It provides strength and rigidity.
What type of linkages connect the sugars in peptidoglycan?
β-1,4 linkages.
How does the cross-linking of peptidoglycan differ in gram-negative and gram-positive bacteria?
It is cross-linked differently, often with 'interbridges' in gram-positive bacteria.
What drives the movement of gliding-specific proteins in the cytoplasmic membrane?
Proton Motive Force (PMF).
What does the cytoplasmic membrane surround?
The cytoplasm.
What is the lower limit of cell size for cellular organisms?
Cellular organisms <0.15 μm in diameter are unlikely.
What is phototaxis?
Response to light.
What type of machine is the flagellum motor?
A reversible rotating machine.
What are the main structural differences between Gram-positive and Gram-negative cell walls?
Gram-negative has at least two layers (LPS and peptidoglycan), while Gram-positive has a thicker, primarily one layer of peptidoglycan.
What are the major components of bacterial lipopolysaccharide (LPS)?
Lipid A, KDO, core, and O-specific polysaccharide.
What is the primary function of the cytoplasmic membrane?
To act as a permeability barrier.
What is osmotaxis?
Response to ionic strength.
What type of machines are flagella described as?
Tiny rotating machines.
What is notable about the genomes of ultramicrobacteria?
They are highly streamlined.
Name another very large prokaryote.
Thiomargarita namibiensis.
What do nonspecific porins do?
Form water-filled channels for virtually any very small hydrophilic substance to pass.
What is the function of specific porins?
Contain a binding site for one or a group of structurally related substances.
What replaces most of the phospholipids in the outer half of the outer membrane?
Lipopolysaccharides (LPS).
What role do Type IV pili play?
They adhere to host tissues and support twitching motility.
What role do capsules and slime layers play in biofilms?
They assist in the development and maintenance of biofilms.
Where is lysozyme found and what is its role?
Found in human secretions, it is a major defense against bacterial infection.
What does chemotaxis refer to?
Response to chemicals.
What is the 'run and tumble' behavior in bacteria?
A movement pattern where bacteria move smoothly forward (run) and then stop and jiggle (tumble).
Why is a certain volume needed in cells?
To house proteins, nucleic acids, ribosomes, and other components.
What is the periplasm?
The space located between the cytoplasmic and outer membranes.
What does aerotaxis respond to?
Oxygen.
What happens during a 'tumble' in bacterial movement?
The motor rotates clockwise, causing the flagellar bundle to come apart.
What is the typical diameter range of ultramicrobacteria?
0.2 – 0.4 μm.
What type of cell shape is associated with swimming motility in viscous environments?
Helical or spiral-shaped cells.
What must polar and charged molecules do to cross the cytoplasmic membrane?
They must be transported.
What proteins surround the rotor in the flagellum?
Mot proteins.
What are porins?
Transmembrane protein channels for entrance and exit of solutes.
What role do protein anchors play in the cytoplasmic membrane?
They hold transport proteins in place.
What is the primary composition of the cell wall in prokaryotes?
Most of the cell wall is composed of the outer membrane or the lipopolysaccharide (LPS) layer.
Are there variations on basic morphological types of prokaryotic cells?
Yes, many variations are known.
What is the general structure of the bacterial cytoplasmic membrane?
A phospholipid bilayer containing embedded proteins.
What are the hydrophobic components of the bacterial cytoplasmic membrane?
Fatty acids.
How do fatty acids orient in the bacterial cytoplasmic membrane?
They point inward to form a hydrophobic environment.
What type of layer does Streptococcus pneumoniae have?
A polysaccharide layer.
What is the width of the bacterial cytoplasmic membrane?
8 – 10 nm wide.
What are hopanoids?
Sterol-like molecules that strengthen some bacterial species' membranes.
What is the size range of flagella?
15 – 20 nm wide.
What does the cytoplasmic membrane separate?
The cytoplasm from the environment.
What role do protons play in the flagellum motor?
Protons flowing through the Mot proteins exert forces on charges present on the C and MS rings, spinning the rotor.
What is transported in and out of the cytoplasmic membrane?
Nutrients are transported in and waste products out.
How do flagella increase or decrease swimming speed?
By varying the rotational speed relative to the strength of the proton motive force.
In which direction does movement typically occur during gliding motility?
Away from the colony.
How do bacteria monitor their environment?
Using chemoreceptors that sense attractants and repellents.
What is required for gliding motility to occur?
Surface contact.
Which type of bacteria is associated with gliding motility?
Filamentous bacteria.
What are spirochetes?
Tightly coiled bacteria.
What is generated by the cytoplasmic membrane that is crucial for energy conservation?
Proton motive force.
What are the components of lipopolysaccharides (LPS)?
Core polysaccharide, O-polysaccharide, and lipid A.
What is the function of conjugative/sex pili?
They facilitate genetic exchange between cells through conjugation.
Which organisms are known to utilize Type IV pili for motility?
Pseudomonas and Moraxella.
What type of linkages do Bacteria and Eukarya have in their phospholipids?
Ester linkages.
What are the major lipids found in Archaea?
Phosphoglycerol diethers and diphosphoglycerol tetraethers.
What unique structure can archaeal lipids form?
Lipid monolayers.
Which bacteria can fully reverse flagellar rotation to avoid tumbling?
Many, such as Pseudomonas.
How wide is the periplasm?
~15 nm.
What is the function of the stator in the flagellum?
To generate torque, a twisting force that causes rotation.
What is the composition of the Gram-positive cell wall?
Primarily one layer of peptidoglycan, which is thicker than that of Gram-negative bacteria.
What does hydrotaxis refer to?
Response to water.
What are some characteristic arrangements of prokaryotic cells after division?
Chains of Streptococcus and grapelike clusters of Staphylococcus.
What is the size range for eukaryotic cells?
2 to >600 μm in diameter.
What is the relationship between energy consumption and the cytoplasmic membrane?
The cytoplasmic membrane is involved in energy conservation and consumption.
What small amount is contained in the total cell wall of prokaryotes?
Peptidoglycan.
What are capsules and slime layers in bacteria?
Structures that assist in attachment to surfaces.
Which amino acids are typically found in peptidoglycan?
L-alanine, D-alanine, D-glutamic acid, and either L-lysine or diaminopimelic acid (DAP).
What enzyme can destroy peptidoglycan?
Lysozyme.
What are the side chains of diphosphoglycerol tetraethers in Archaea?
Biphytanyl C40 side chains.
What is a characteristic of a capsule?
It is tightly attached, has a tight matrix, and can exclude particles.
What is a characteristic of a slime layer?
It is loosely attached, easily deformed, and cannot exclude particles.
What is the typical width of fimbriae and pili?
~2 – 10 nm.
What components are found in the bacterial cytoplasmic membrane?
Hydrophobic and hydrophilic components.
What are the hydrophilic components of the bacterial cytoplasmic membrane?
Glycerol, phosphate, and another functional group (e.g., sugars, ethanolamine, choline).
What remains exposed to the external environment or the cytoplasm in the bacterial cytoplasmic membrane?
The hydrophilic portions.
What is one function of capsules and slime layers regarding dehydration?
They prevent dehydration/desiccation.
What gastrointestinal symptoms are associated with lipid A from LPS?
Gas, diarrhea, and vomiting.
How does the chemistry of lipid A and O-specific polysaccharide vary?
It varies among species of gram-negative bacteria.
What role does the outer membrane play in prokaryotic cells?
It acts as a barrier against antibiotics and other harmful agents.
How do pili differ from fimbriae?
Pili are typically longer and fewer in number (1 or a few) compared to fimbriae.
What are the two modified glucose components of peptidoglycan?
N-acetylglucosamine and N-acetylmuramic acid.
How do capsules act as virulence factors?
They block host immune cells.
What do archaeal lipids contain instead of fatty acids?
Isoprenes.
What are the side chains of phosphoglycerol diethers in Archaea?
Phytanyl C20 side chains.
What is lipid A in the context of LPS?
Lipid A is the toxic component of LPS, also known as an endotoxin.
What type of linkages do archaeal membranes have in their phospholipids?
Ether linkages.
What type of layer does Bacillus anthracis have?
A protein layer.
Examples of gliding motility mechanisms
excretion of polysaccharide slime, type IV pili/ twitching motility, gliding-specific proteins
