Micro Chapter 3 bacterial cell structure

the cell wall is sculpted by the actin homologue _____ and related proteins, and the filaments associate with the plasma membrane to do what for the cell

MReB and related proteins, whose filaments associate with the plasma membrane and position the enzymes that synthesize peptidoglycan as the cell grows

the outer leaflet (facing the environment) of gram-negative cells are comprised of ____________

Lipopolysaccharides (LPS)

motile bacteria can move in response to what environmental cues

cues such as temperature (thermotaxis), light (phototaxis), oxygen (aerotaxis), osmotic pressure (osmotaxis), magnetic fields (magnetotaxis), and gravity

in bacteria and archaea, ribosomes and larger masses called inclusions are scattered about the __________

cytoplasm

the _______ is the material bounded by the plasma membrane

cytoplasm

the plasma membrane surrounds the ______

cytoplasm

as electrons are transported down the ETC, protons are transported from the _______ to the _______ of the cell

cytoplasm to the outside of the cell

the liquid component of the cytoplasm is called the

cytosol

what are the two types of cross-linking

direct and indirect

what are endospores

dormant cells formed within a so-called mother cell, are fascinating bacterial structures produced by certain bacteria within the phylum Firmicutes

gram-___________ bacteria form endospores and have typical _______ (word for 1 layer) cell walls

gram-positive; monoderm

inclusions can take the form of ______, ______, or _____; some are amophous

granules, crystals, or globules

what are lophotrichous bacteria

have a cluster of flagella at one or both ends

what are amphitrichous bacteria

have a single flagellum at each pole

what is amphipathic

having both hydrophilic and hydrophobic parts; phospholipids are amphipathic because they are structurally asymmetric, with polar and nonpolar ends

what are some important functions of teichoic acids

help create and maintain the structure of the cell envelop by anchoring the wall to the plasma membrane; important during cell division, and they protect the cell from harmful substances in the environment (e.g., antibiotics and host defense molecules); they function in ion uptake and are involved in binding pathogenic species to host tissues, thus initiating the infection disease process

what are some benefits of capsules

help pathogenic bacteria resist phagocytosis by host phagocytes protect against desiccation because they contain a great deal of water exclude viruses and most hydrophobic toxic materials such as detergents

where are the chemosensing systems located

in the plasma membrane

in bacteria and archaea, ribosomes and larger masses are called ___________ and found where

inclusions and found scattered about the cytoplasm

transport across the outer membrane is facilitated by _________ ________ proteins, including one class of proteins termed __________

integral membrane proteins; porins

what are magnetosomes and what are they composed of

intracellular chains of magnetite (Fe3O4) or greigite (Fe3S4) particles enclosed within invaginations of the plasma membrane. The invaginations contain distinctive proteins and thus constitute functional membrane microdomains. For the cell to move properly within a magnetic field, magnetosomes must be arranged in a chain. The cytoskeletal protein MamK establishes a framework upon which the chain can form

the internal membranous structures observed in bacteria are often connected to the plasma membrane and arise from it by _________. However, these internal membranes differ from the plasma membrane by being ______ for molecules involved in energy conservation

invagination; enriched

what is twitching motility and how is it characterized

is characterized by short, intermittent, jerky motions of up to several micrometers in length and is normally seen on moist surfaces. Type IV pili alternately extend and retract to move cells during twitching motility. The extended pilus contacts the surface at a point some distance from the cell body. When the pilus retracts, the cell is pulled forward. ATP hydrolysis powers the extension/retraction process.

what are some benefits of a cell wall

it helps maintain cell shape and protects the cell from osmotic lysis; it can protect the cell from toxic substances; it can contribute to the ability of a pathogen to cause disease

what does penicillin do to peptidoglycan

it inhibits the enzyme transpeptidase, which is responsible for making the cross-links between peptidoglycan chains. results in complete loss of the cell wall

how does the outer membrane act as an effective barrier for the cell

its asymmetry contributes significantly to this effect. within the lipopolysaccharides (LPS) the negatively charged phosphate groups on the core polysaccharide interact with calcium ions to stabilize and tightly pack the LPS molecules. This results in an impermeable barrier that excludes small molecules, including many antibiotics and toxins

what do prokaryotes lack that eukaryotes have?

lack a membrane-bound nucleus, a cytoskeleton, membrane-bound organelles, internal membranous structures such as the endoplasmic reticulum and golgi apparatus

the function of internal membranes is to provide a __________ membrane surface for greater metabolic activity

larger

Rather than typical membrane transporters, many bacteria secrete __________ (Greek for iron bearers)

siderophores. Siderophores are small organic molecules that bind ferric iron and supply it to the cell Microorganisms secrete siderophores when iron is scarce in the medium.

what is vegetative growth

the normal, continuous cycle of growth and cell division

what is a protoplast

the plasma membrane and everything within it, a bacterial, archaeal, or fungal cell with its cell wall completely removed. it is spherical in shape and osmotically sensitive

what is passive diffusion (also called "diffusion" or just "simple diffusion") and what does its rate depend on

the process by which molecules move from a region of higher concentration to one of lower concentration (molecules move down the concentration gradient); rate depends on the size of the concentration gradient between cells exterior and interior (a large concentration gradient is required for adequate nutrient uptake by passive diffusion)

what is sporulation and when does it occur

the process of endospore formation commences when growth slows due to nutrient limitation. It is thus a survival mechanism that allows the bacterium to produce a dormant cell that can persist until nutrients are available and vegetative growth can resume

what is a forespore

the smaller of two unequal cells that result from stage II of sporulation, which will become the endospore

what is hypertonic solution

the solute concentration is higher than that in the cytoplasm

what is a hypotonic solution

the solute concentration is less than that in the cytoplasm

what is active transport and what are the three types

the transport of solute molecules to higher concentrations against the concentration gradient with the input of energy; primary active transport secondary active transport group translocation (They differ in terms of the energy used to drive transport and whether or not the transported molecule is modified as it enters.)

plasma membrane-associated ribosomes make proteins that will _________ in the cell envelope or be transported to the _________

reside in the cell envelope or be transported to the outside

bacterial ribosomes are composed primarily of _________ molecules. The small subunit contains _____ rRNA, whereas the large subunit consists of 23S and 5S rRNA molecules. Approximately 55 proteins make up the rest of the mass of the ribosome: 21 in the small subunit, and 34 in the large subunit.

ribosomal RNA (rRNA)

what shape is bacterial flagellum

rigid helix

bacilli (singular: bacillus) are what shape

rod shaped

cocci (singular: coccus) are what shape

roughly spherical

what are the two types of movement caused by flagellar rotation by bacteria in an aquatic environment

run - a smooth swimming movement which moves the cell from one spot to another tumble - serves to reorient the cell

the primary role of all plasma membranes is that they are ___________ __________ ________. In bacteria, plasma membranes play additional critical rolls - they are the location of several crucial metabolic processes: ______, ___________, and the synthesis of ________ and _____ _____ constituents

selectively permeable barriers - they allow molecules to pass either into or out of the cell, while preventing the movement of others. respiration, photosynthesis, and the synthesis of lipids and cell wall constituents

what does the enzyme lysozyme do to peptidoglycan

attacks peptidoglycan by hydrolyzing the bond that connects N-acetylmuramic acid with N-acetylglucoasmine

what are pleomorphic bacteria

bacteria that can appear in a variety of shapes

what is monoderm

bacteria that have a single membrane (typical of gram-positive bacteria)

what is diderms

bacteria that have both a plasma membrane surrounding the cytoplasm and an outer membrane surrounding the periplasm (typical of gram-negative bacteria)

what are monotrichous bacteria

bacteria that have one flagellum

what are polar flagellum

bacteria that have one flagellum and it is located at an end

what are microcompartments

bacterial inclusions that are relatively large polyhedra

bacterial ribosomes are called __________ ribosomes and are constructed of a ______ and a ______ subunit

70S; 50S and 30S subunit

what is a sex pili

A thin protein appendage required for bacterial conjugation. The cell with sex pili donates DNA to recipient cells. Sex pili often are larger than other pili (around 9 to 10 nm in diameter); They are genetically encoded on plasmids and are required for conjugation; Some bacterial viruses attach specifically to sex pili at the start of their infection cycle.

what is gliding motility and how is it characterized

A type of motility in which a microbial cell glides smoothly along a solid surface without the aid of flagella

what are ATP-Binding Cassette transporters (ABC transporters)

ATP-Binding Cassette transporters (ABC transporters) are important primary active transporters, responsible for moving substrates such as vitamins, ions, and sugars.

what is a peptide interbridge and what bacteria usually have it (gram pos/neg)

Bacteria that have indirect linkage use a peptide interbridge (also called an interpeptide bridge), a short chain of amino acids linking the stem peptide of one peptidoglycan strand to that of another typical of gram-positive bacteria

In the curved bacterium Caulobacter crescentus, the ______ protein localizes to the inner surface of the curve

CreS protein (a homologue of eukaryotic intermediate filaments)

plasmids use the cell's __________-________ machinery to replicate, but their replication is _________ (linked/not linked) to a(ny) particular stage of the cell cycle

DNA-synthesizing machinery; not linked

what are extracellular vesicles (EVs) and how do they form in gram-negative cells

EVs that form from a typical Gram-negative cell are composed of the lipopolysaccharide-containing outer membrane surrounding a sample of periplasm, and these structures are also referred to as outer membrane vesicles (OMVs). The outer membrane needs to dissociate from Braun's lipoprotein before it can grow outward. Other particles originating from Gram-negative bacteria contain both plasma and outer membranes enclosing cytoplasm and periplasm, respectively.

how do flagellum grow

Many components of the flagellum lie outside the cell envelope and must be transported out of the cell for assembly. Individual flagellin subunits are transported through the hollow filament. When the subunits reach the tip, they spontaneously aggregate under the direction of a protein called the filament cap; thus the filament grows at its tip rather than at the base (figure 3.40). Filament synthesis, like S-layer formation, is an example of self-assembly that occurs without the aid of enzymes or other factors.

Architectural proteins also contribute to nucleoid structure. __________________ are small, abundant DNA binding proteins that cause the chromosome to bend and fold

Nucleoid associated proteins (NAPs)

many bacteria have an ordered surface covering called an _____-______

S-layer; S-layer proteins contain the information required to spontaneously associate and form the S-layer without the aid of any additional factors.

what are siderophores

Siderophores are small organic molecules that bind ferric iron and supply it to the cell Once the iron-siderophore complex reaches the cell surface, it binds to a siderophore-receptor protein. Then either the iron is released to enter the cell directly or the whole iron-siderophore complex is transported inside by an ABC transporter

what sugars and amino acids make up peptidoglycan, and what is peptidoglycan sacculus

Single molecule covering the entire plasma membrane that is composed of many identical subunits. each subunit contains two sugar derivatives, N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM). Each subunit has several different amino acids which form a short bond called a peptide bond, sometimes called a stem peptide, consisting of four alternating d- and L- amino acids; the peptide is connected to the carboxyl group of NAM. Three of the amino acids are not found in proteins: d-glutamic acid, d-alanine, and meso-diaminopimelic acid. The presence of d-amino acids in the stem peptide protects against degradation by most peptidases, which recognize only the L-isomers of amino acid residues.

What are growth factors

Some microbes are unable to synthesize certain organic molecules needed for survival. These molecules are called growth factors, and they must be obtained from the environment Organic compounds that must be supplied in the diet for growth because they are essential cell components or precursors of such components and cannot be synthesized by the organism.

What do fimbriae do?

attach cells to solid surfaces such as rocks in streams and host tissues

what are the seven steps of sporulation (of the studied Bacillus subtilis)

Stage I - the chromosome replicates, followed by cell division. Stage II - The division septum is set down away from the center of the cell, resulting in two unequal cells (surrounded by one cell wall) Stage III - the mother cell continues to grow to engulf the forespore in a second membrane (called the outer membrane) Stage IV - between the forespore and mother cell membranes, peptidoglycan is synthesized; The inner layer, the germ cell wall, is chemically similar to vegetative cell wall PG. The outer layer, the cortex, has PG with fewer cross-links. These PG layers are critical in counteracting osmosis as the core dehydrates. Atop the outer membrane is the coat, a complex structure composed of more than 80 different proteins highly cross-linked to each other Stage V - the coat proteins are synthesized in the mother cell and deposited on the forespore surface Stage VI - is characterized by continued dehydration that results in changes in the forespore resistance properties, such that physical and chemical insults are no longer lethal. Stage VII - the mother cell sporangium lyses to release the mature endospore. In some species, endospores are enclosed by a thin glycoprotein covering, the exosporium. The exposporium is hydrophobic, which allows the endospores to adhere to surfaces.

what shape are the chromosomes of most bacteria and what is it made of

a circle of double-stranded DNA; a few bacteria have a linear chromosome;

what is flagellin

a family of related proteins used to construct the filament of a flagellum

what is group translocation

a molecule is chemically modified as it is brought into the cell; the best-known group translocation system is the phosphoenolpyruvate: sugar phosphotransferase system (PTS)

what is the cytoskeleton

a network of structures made from filamentous proteins (e.g., actin and tubulin) and other components in the cytoplasm of cells; Individual cytoskeleton polypeptides polymerize to form functional filaments that often extend to the full inner dimensions of the cell.

what is a macronutrient

a nutrient that is required in relatively large amounts (e.g., carbon and nitrogen)

what is a spheroplast

a spherical cell formed by the weakening or partial removal of the rigid cell wall component

what is macromolecular crowding

abundant solutes result in less available space around each molecule (same as driving through a city in rush hour)

some bacterial and archaeal cytoskeleton proteins share common ancestors with _____ and _______, components of the eukaryotic cytoskeleton

actin and tubulin

what are the three stages a dormant endospore goes through to become active vegetative cells

activation - prepares endospores for germination and results from treatments such as brief heating to a sublethal temperature which may cause conformation changes in germination proteins germination - the breaking of the endospore's dormant state. It begins when proteins called germinant receptors, located in the inner membrane and the cortex, detect small molecules such as sugars and amino acids. These activated receptors trigger the release of the Ca-DPA complexes and water uptake. Cortex peptidoglycan is broken down, allowing the core to expand and hydrate further. outgrowth - Eventually water levels inside the germinating cell reach those characteristics of vegetative cells, causing enzymes in the core to reactivate. This allows the endospore to synthesize molecules required for outgrowth and return to a vegetative state

what do MotA and MotB proteins allow?

allow protons to move across the plasma membrane from the outside to the inside; thus protons move down the charge and pH gradient. This movement releases energy that rotates the flagellum

what are extracellular vesicles (EVs) and how do they form in gram-positive cells

also called a membrane vesicle, are small membrane-bound particles. Extracellular vesicles are membrane-bound nanoparticles consisting of a sample of the cytoplasm and its contents. composed of the plasma membrane surrounding a small amount of cytoplasm they develop when a membrane buds out, pinches off, and is released from a cell Osmotic pressure in Gram-positive cells appears to force EVs through pores in the peptidoglycan.

what are nucleoid associated proteins (NAPs)

architectural proteins that bind by electrostatic interaction. NAPs have a track of positively charged amino acids on their surface that aligns with the negatively charged DNA backbone. This type of interaction allows the proteins to move on and off the DNA as the DNA engages in its other cellular roles. On short segments of DNA, certain NAPs bend or stiffen the chromosome (figure 3.36a,b,c); on a global level, other NAPs bridge nonadjacent regions of the chromosome (figure 3.36d). NAPs are particularly important during cell division, when they further compact the chromosome. This extra level of packing is important for proper segregation of daughter chromosomes during cell division

what are type IV pilus

are involved in motility (section 3.9) and two gene transfer mechanisms: transformation and conjugation. fine, hairlike appendage of some bacterial cells that can mediate twitching motility or DNA uptake

the ion gradients used by secondary active transporters arise primarily in what three ways

bacterial metabolic activity generated during electron transport in which protons are at a higher concentration outside the cell than inside. This gradient is used to do cellular work, including secondary active transport Some bacteria use the second method, in which an enzyme called a V-type ATPase hydrolyzes ATP and uses the energy released to create either a proton gradient or a sodium gradient across the plasma membrane. Finally, a proton gradient can be used to create another ion gradient such as a sodium gradient. This is accomplished by an antiporter that brings protons in as sodium ions are moved out of the cell. The sodium gradient can then be used to drive uptake of nutrients by a symport mechanism

the motor that drives flagellar rotation is located in the ________ ____

basal body

many bacteria surround the cell wall with a _______ or a _________ ______

capsule or a slime layer

what are the most common cell envelope layers from external to internal?

capsule or slime layer, cell wall, plasma membrane

direct cross-link is characterized by connecting the ______ group of an amino acid in one stem peptide to the amino group of an amino acid in another stem peptide

carboxyl many bacteria cross-link the strands by connecting the carboxyl group of the d-alanine at position 4 of the stem peptide directly to the amino group of diaminopimelic acid (position 3) of the other peptidoglycan strand's stem peptide. The position 5 d-alanine is removed as the cross-link is formed

what are Cotransporters and what are the two types

carrier protein that simultaneously moves two substances across the membrane; symporter is when both substances move in the same direction; antiporter is when the two substances move in opposite directions

cytoskeleton polypeptides that form function filaments have what important roles

cell division, maintaining cell shape, and positioning and segregating inclusions and plasmid DNA

Bacterial cells are surrounded by several layers, which are collectively called the ______ ______, which is defined as the plasma membrane and all surrounding layers external to it

cell envelope

the morphology of rod-shaped bacterial cells is conferred by their rigid _____ _____

cell walls

the dense protein coat protects endospore from _____ and _____ enzymes such as lysozyme

chemicals and lytic enzymes

attractants and repellents are detected by ___________, proteins that bind chemicals and transmit signals to other components of the chemosensing system

chemoreceptors

thylakoids of cyanobacteria contain the ___ and ___ reaction centers responsible for converting light energy into ATP

chlorophyll and photosynthetic reaction centers

vibrios are what shape

comma-shaped

Lipopolysaccharides (LPS) have what important functions

contribute to the negative charge of the bacterial surface because the core polysaccharide usually contains charged sugars and phosphate helps stabilize the outer membrane structure because lipid A is a major constituent of the exterior leaflet of the outer membrane helps create a permeability barrier protects pathogenic bacteria from host defense - The O side chain of LPS is also called the O antigen because it elicits an immune response by an infected host.

(capsule - polysaccharides) in typical gram-negative bacteria, these polysaccharides are __________ bonded to outer membrane lipids, and therefore are not easily washed away

covalently

bacteria that stain gram positive tend to have much more __________-_______, whereas those that stain gram negative have considerably less ______-_______

cross-linking; cross-linking

what are plasmids and what are the two types

double-stranded DNA molecules that can exist independently of the chromosome; Contain relatively few genes, generally less than 30; their genetic information is not essential to the bacterium, and cells that lack them usually function normally. However, many plasmids carry genes that confer a selective advantage to the bacterium in certain environments circular and linear, but most known plasmids are circular

some photosynthetic bacteria use hydrogen sulfide (rather than water) as an _________ ________ and accumulate the resulting sulfur either externally or internally

electron donor

what is the nucleoid

ellipsoidal region that contains the cell's chromosome and numerous proteins and occupies about 20% of cell volume; ribosomes are excluded from the nucleoid

enclosed within the protein shell are one or more _________

enzymes

what are the three parts of flagellum

filament - the longest and most obvious portion, extends from the cell surface to the tip. a hollow, rigid cylinder constructed of subunits of the protein flagellin, the filament ends with a capping protein basal body - which is embedded in the cell envelope. The basal body is the most complex part of a flagellum; Gram-negative bacteria have four rings: L, P, MS, and C, which are connected to a central rod (figure 3.39a). The L, P, and MS rings are embedded in the lipopolysaccharide, peptidoglycan, and plasma membrane, respectively, and the C ring is on the cytoplasmic side of the MS ring; Gram-positive bacteria have only two rings: an inner ring connected to the plasma membrane and an outer one probably attached to the peptidoglycan hook - a short, curved segment that links the filament to its basal body and acts as a flexible coupling, made of different protein subunits than the filament

what are fimbria (s., fimbria) and pili (s., pilus)

fine, hairlike appendages that are thinner and typically shorter than flagella; They are slender tubes composed of helically arranged protein subunits and are about 3 to 10 nm in diameter and up to several micrometers long. Pili grow by adding protein subunits to their base certain structures are historically called pili, while others are called fimbriae only visible in an electron microscope due to their small size

what two phyla do most bacteria that stain gram positive belong too

firmicutes and actinobacteriota

why is transport into a gram-negative cell considered a two-step process?

first - solutes must cross the outer membrane; and once in the periplasm the solutes must then move across the plasma membrane

in bacteria and archaea, _____ are used for locomotion

flagella

what are peritrichous bacteria

flagella are spread evenly over the whole surface

spirochetes are what shape

flexible, spiral-shaped

the endospore core begins as the ______ cytoplasm and its plasma membrane

forespore

myxobacteria are morphologically complex due to sometimes aggregating to form a structure called a ________ __________

fruiting body

what two inclusions are involved in bacterial movement and what are they and how do they work

gas vacuole - provides buoyancy to some aquatic bacteria, many of which are photosynthetic. gas vacuoles are aggregates of enormous numbers of small, hollow, cylindrical structures called gas vesicles magnetosomes - aquatic bacteria use magnetosomes to orient themselves in earth's magnetic field. northern hemisphere bacteria use their magnetosome chain to determine northward and downward directions, and swim to nutrient-rich sediments or locate the optimum depth in freshwater and marine habitats southern hemisphere generally orient southward and downward, with the same result

the term ________ also describes a polysaccharide layer extending from the cell surface. The term encompasses both capsules and slime layers because both are composed of polysaccharides. The _________ aids in attachment to _______ surfaces, including tissue surfaces of plant and animal hosts

glycocalyx; glycocalyx; solid surfaces

the most common storage inclusions are ________ inclusion, ________ _____ granules, _______ globules, and _________ granules

glycogen inclusions, polyhydroxyalkanoate (PHA) granules, sulfur globules, and polyphosphate granules

Lipopolysaccharides consist of what 3 parts

lipid A - contains two glucosamine sugar derivatives, each with fatty acids and phosphate attached. The fatty acids of lipid A comprise the hydrophobic component of the outer leaflet, whereas the remainder of the LPS molecule projects from the surface the core polysaccharide - is joined to lipid A and is constructed of 10 sugars, many of them unusual in structure. the O side chain (or "O antigen") - is a polysaccharide chain extending outward from the core. It has several unusual sugars and varies in composition between bacterial strains

teichoic acids that are covalently bonded to the plasma membrane are called ______ _____

lipoteichoic acids

what are hyphae actinobacteria

many actinobacteria form long filaments called hyphae. The hyphae form a network called a mycelium, and in this sense, they are similar to eukaryotic filamentous fungi

what is primary active transport

mediated by carriers called primary active transporters that use energy provided by ATP hydrolysis (A-B + H2O --> A-H + B-OH) Primary active transporters are uniporters; that is, they move a single molecule across the membrane

what is chemotaxis

movement toward chemical attractants and away from repellents

__________ ________ plasmids may be present at concentrations of 100 or more per cell

multicopy plasmids

what are the two groups of bacteria that do not have a cell wall

mycoplasma species L-forms that arise from either gram-positive or gram-negative bacterial cells that have lost their ability to produce the peptidoglycan structures

do bacteria move aimlessly

no, motility is used to move toward nutrients such as sugars and amino acids and away from many harmful substances and bacterial waste products;

in typical gram-negative bacteria, the S-layer adheres __________________ to the outer membrane, and in gram-positive cells it is associated with the _______________ surface

noncovalently; peptidoglycan

in bacteria and archaea the genetic material is localized in a discrete region called the _______ and is not separated from the surrounding cytoplasm by a membrane

nucleoid

in bacteria genetic material is localized in a discrete region called the ________

nucleoid

bacterial endospore formation is a response to what and what does it represent

nutrient depletion, and the endospores represent a dormant stage of the organism

What is a micronutrient

nutrients required in very small quantities for growth and reproduction. Also called "trace elements" Micronutrients are part of certain enzymes, and they aid in catalysis of reactions and maintenance of protein structure.

how does sporulation occur

occurs over several hours; the mature endospore occupies a characteristic location in the mother cell (referred to as the sporangium); Endospores may be centrally located, close to one end (subterminal), or terminal (figure 3.46). Sometimes an endospore is so large that it swells the sporangium

Plasmids can differ in terms of the number of copies found within the cell. Single-copy plasmids produce _________ copy per host cell

one

inclusions are formed by the aggregation of substances that may be either _______ or _________

organic or inorganic

what do the integral membrane proteins called flotillins do

organize secretion systems for transporting molecules out of the cell and complexes that transmit signals from the environment to molecules in the cytoplasm

when typical gram-negative bacteria are exposed to lysozyme or penicillin, the peptidoglycan sacculus is destroyed, but the ________ membrane remains.

outer membrane

Extracellular vesicles (EVs) fuse with the _________ __________ of other gram-negative cells and release their contents into the ___________

outer membrane; periplasm

what are the 5 types of membrane transport mechanisms in bacteria

passive diffusion, facilitated diffusion, primary and secondary active transport, and group translocation

the cell walls of typical gram-positive bacteria consist of a single, 20- to 80-nm-thick layer of ____________ (murein)

peptidoglycan

what layer of the cell wall prevents the cell from lysis

peptidoglycan layer

the cell walls of typical Gram-negative bacteria have two distinct layers: a 2- to 7-nm-thick ______ layer covered by a 12- to 14-nm-thick _________ __________

peptidoglycan layer; outer membrane

The feature common to nearly all bacterial cell walls is the presence of peptidoglycan, which forms an enormous meshlike structure often referred to as the ________ ___________

peptidoglycan sacculus

the space observed between the plasma and outer membrane in gram-negative bacteria is known as the _________ ________ and the substance that occupies the space is called _____________

periplasmic space; periplasm

Polyphosphate granules store what and why

phosphate needed for synthesis of important cell constituents such as nucleic acids; in some cells, they act as an energy reserve, and polyphosphate also can serve as an energy source in some reactions, when the bond linking the final phosphate in the polyphosphate chain is hydrolyzed

plasma membranes are composed of ______ molecules arranged end-to-end. Bacterial membranes have roughly equal amounts of ______ and ______.

phospholipids; lipids and proteins

in bacteria and archaea, filamentous structures are called ________ and may protrude from ________, and facilitate ____ ________ or _______ ____ ________

pili (singular: pilus) and may protrude from the surface and facilitate gene transfer or attachment to surfaces

in bacterial cells, most components of the ETC are located in the ________ ________

plasma membrane

the innermost layer of the cell envelope is called the _______ _________

plasma membrane

the most common cell envelope layers are the ____ ______, ________ ______, and _________ or _______ __________

plasma membrane, cell wall, and capsule or slime layer

what are episomes

plasmids that are able to integrate into the chromosome. when integrated the are replicated as part of the chromosome

what are functional membrane microdomains

platforms for large protein complex assembly; arise from hopanoids distorting membrane regions

carbon is often stored as ______________ granules, also termed _________

polyhydroxyalkanoate (PHA) granules called carbonosomes

what is teichoic acids

polymers of glycerol or ribitol joined by phosphate groups

a slime layer is also a _______ layer, but it differs from a capsule in being more ________ and _______, and more easily removed from the cell

polysaccharide layer diffuse and unorganized

capsules are well-organized layers that are most often composed of _________

polysaccharides

what are some of the biological roles of S-layers

protecting the cell against ion and pH fluctions, osmotic stress, enzymes, or predatory bacteria. helps maintain the shape and envelope rigidity of some cells, and it can promote adhesion to surfaces. protects some bacterial pathogens against host defenses, thus contributing to their virulence

The S-layer is composed of ____ or _______

protein or glycoprotein; S-layer proteins contain the information required to spontaneously associate and form the S-layer without the aid of any additional factors.

because bacteria lack membrane-bound organelles, microcompartments are often bounded by a _______ ______

protein shell

Ribosomes are the site of _____ _______

protein synthesis

what are channel and carrier transport proteins

proteins that form pores in cell membranes through which substances can pass (often involved in facilitated diffusion) carrier transport proteins are more specific in the substrate that they carry across the membrane than channel transport proteins

a bacteria, archaeal, or fungal cell that has had its cell wall removed is called a ___________

protoplast

the plasma membrane and everything within it is called the

protoplast

cytoplasmic ribosomes synthesize proteins destined to ___________

remain within the cell

what are hopanoids

similar structure to cholesterol found in eukaryotic membranes, and their rigid planar structure makes them more hydrophobic than phospholipids, so they sit between the phospholipid membrane layer and distort its shape which affects fluidity and shape in membrane regions, which in turns determines where certain integral membrane proteins can reside

bacteria that produce endospores make a _________ endospore per cell that later ________ to a single cell

single; germinates; thus there is no increase in the number of cells

many bacteria carry a ______ copy of their chromosome (monoploid), but others are _____________, often with more than 10 copies per cell

single; polyploid

what are gas vesicles and what are their walls composed of

small, hollow, cylindrical structures; gas vesicle walls are composed of many copies of a single small protein. these protein subunits assemble to form a rigid cylinder that is impermeable to water but freely permeable to atmospheric gases; cells with gas vacuoles regulate their buoyancy to float at the depth necessary for proper light intensity, oxygen concentration, and nutrient levels; they descend by simply collapsing vesicles and float upward when new ones are constructed

twitching and gliding motility occurs when cells are on a _____ surface

solid

spirilla are what shape

spiral-shaped

what is facilitated diffusion

substances move across the plasma membrane with the assistance of transport proteins that are either channels or carriers

sulfur globules are formed by bacteria that use ________-________ compounds as a source of ________ during their energy-conserving metabolic processes

sulfur-containing compounds as a source of electrons

swarming motility requires the production of a ______, a class of chemical that ________ the surface tension of the substrate to facilitate movement

surfactant; lowers

what are the five major methods of movement that have been observed by bacteria

swimming movement conferred by flagella; flagella-mediated swarming; corkscrew movement of spirochetes; twitching motility associated with type IV pili; gliding motility

what is translation

the decoding of an mRNA message into a protein (process of protein synthesis)

what is the power source used by most flagellar motors

the difference in charge and pH across the plasma membrane called the "proton motive force" (PMF) Because there are more protons outside the cell than inside, the outside has more positively charged ions (the protons) and a lower pH

why are some enzymes in microcompartments that have a protein shell

the enzymes may have a chemical reaction or pathway that they catalyze that in some cases, the reaction produces a toxic intermediate, and in others the reactant is a gas that could easily pass through a lipid membrane

what is the sprangium (or mother cell)

the larger cell that supports endospore construction that results from stage II of sporulation

what are flagella and what can they do

threadlike locomotor appendages extending outward from the plasma membrane and cell wall main function is motility, although they can be involved in attachment to surfaces, and in some bacteria, they are virulence factors; that is, they contribute to the ability of the bacterium to cause disease.

Although bacteria do not contain complex membranous organelles like mitochondria or chloroplasts, internal membranous structures are observed in some cells (figure 3.31). These can be extensive and complex in bacteria with high respiratory activity, such as nitrifying bacteria and photosynthetic bacteria. The internal membranes of the photosynthetic cyanobacteria are called __________ and are analogous to the thylakoids of chloroplasts

thylakoids

the primary function of inclusions is to

to segregate certain cellular components so they do not diffuse freely in the cytoplasm; they function as storage sites, locations to sequester enzymatic reactions, or guides for cell movement.

what is the sugar phosphotransferase system (PTS)

translocation system that imports a variety of sugars while phosphorylating them, using phosphoenolpyruvate (PEP) as the phosphate donor. in e. coli and salmonella, the PTS consists of two enzymes (enzyme I and enzyme II) and low molecular weight heat-stable protein (HPr) Many different PTSs exist, and they vary in terms of the sugars they transport. The specificity lies with the type of Enzyme II used in the PTS.

FtsZ is a _______ homologue in cytoskeletal proteins in bacteria and archaea. Its filaments form a ring at the center of a _________ cell that _______ as the daughter cells separate

tubulin; dividing; constricts

if the concentration of an attractant is increasing, __________ is suppressed

tumbling (so bacteria eventually gets closer to attractant)

what happens during the shift from vegetative growth to endospore formation

two side-by-side cells transitioning to one engulfing the other; the folding and arrangement of the cell envelopes in these two cells give the endospore its multiple layers

what is swarming motility

type of group behavior in which cells move in unison across a moist surface; It is the means by which cells colonize plant roots in soil and certain tissues in the body. Swarming requires flagella, and most swarming bacteria have peritrichous flagella.

spirochete motility is best described as what and how does it cause bacteria to move

undulation of the entire cell; Motility is conferred by periplasmic flagella that arise from each end of the cell and wind around the cell but are inside the cell wall (figure 3.43). These endoflagella rotate like the external flagella of other bacteria, causing the corkscrew-shaped outer membrane to rotate and move the cell through the surrounding medium.

what is a Svedberg unit (S)

unit of the sedimentation coefficient, a measure of sedimentation velocity in a centrifuge; the faster a particle travels when centrifuged, the greater its Svedberg value; The sedimentation coefficient is a function of a particle's molecular weight, volume, and shape. Heavier and more compact particles normally have larger Svedberg numbers

what is secondary active transport

uses the potential energy of ion gradients to transport substances without modifying them; secondary active transporters are cotransporters because they move two substances simultaneously

what are the two stages that endospore-forming bacteria cycle between

vegetative growth and survival as an endospore

Some teichoic acids are covalently linked to peptidoglycan and are referred to as _____ ______ _____

wall teichoic acids

why does the cell wall have a negative charge

wall teichoic acids extend beyond the surface of the peptidoglycan, and the negatively charged phosphates give the cell wall its negative charge

diplococci (singular: diplococcus) are what shape and how do they form

when cocci divide and remain together to form pairs

many storage inclusions form when

when one nutrient is in ready supply but another nutrient is not; others store end products of metabolic processes, where in some cases the end products are used by the microbe when it is in different environmental conditions

what is plasmolysis

when water flows out of the cell and the cytoplasm shrivels up

why is hydrolysis

where a water molecule acts as a nucleophile and attacks an electrophile, where it then loses an H+ and leaves an OH- https://www.khanacademy.org/science/biology/energy-and-enzymes/atp-reaction-coupling/v/atp-hydrolysis-mechanism