Module 2: Bacteria + Archaea

True or False: Encapsulated bacterial cells generally have greater pathogenicity

True capsules protect bacteria from phagocytes, enhancing their pathogenicity in most cases

Encapsulated bacteria

(a) negative staining; well-developed capsules (b) colony appearance nonencapsulated = left encapsulated = right

Which of the following is/are prone to biofilm accumulation? - All of these - Artificial heart valves - Catheters - Teeth

All these structures are prone to biofilm accumulation

True or False: Most bacterial genera are capable of forming endospores

Endospores are produced by the genera Bacillus, Clostridium, and Sporosarcina

Bacterial Taxonomy

smallest to largest

vibrio

- gently curved bacterium - rod-shaped Vibrio cholerae

Mycoplasma pneumoniae lacks a cell wall and is termed pleomorphic

True

The production of which substance leads to thickening of the biofilm over time? - exopolymer - IL-4 - lysozyme - exotoxin

exopolymer production of exopolymer by attached bacteria makes the binding irreversible and leads to further recruitment of other cells to the biofilm.

In the final step of spore formation, a _____ coat forms around the cortex. lipopolysaccharide protein lipid membrane peptidoglycan

the final step of spore formation, a protein coat forms around the cortex and the spore becomes mature

True or False: When a spore germinates, it gives rise to 2 vegetative cells

when a spore germinates, it gives rise to one vegetative cell

bacterial chromosome structure

- circular body that contains DNA - also called nucleoid Salmonella enteritidis cytoplasm = orange chromosome = yellow

True or False: Biofilms are composed of a single bacterial species

False in the natural environment, biofilms often consist of different types of organisms that function together in the cycling of nutrients

True or False: When the bacterial glycocalyx is easily removed, it is called a capsule

False when the bacterial glycocalyx is easily removed, it is called a slime layer

The presence of variation in size and shape of cells of a single species of bacteria is known as: hermaphrodism pleomorphism plasticity pleotropism

Pleomorphism is a term used to describe cell morphology when there is a variety of sizes, shapes, and arrangements among cells of a single bacterial species.

After Gram's iodine is added, what color do the cells appear under a light microscope? All cells appear pink/red All cells appear colorless All cells appear purple Some cells may be purple and some may be pink/red

after iodine is added to a smear, all the cells appear purple

The cortex is formed from _____. peptidoglycan flagellar proteins protein cell membrane

after the developing spore is surrounded by the double membrane, peptidoglycan is laid down to form the cortex

The developing spore is surrounded by the cytoplasm of the mother cell the membrane of the mother cell the cell wall of the mother cell proteins produced by the mother cell

after the forespore is produced, the membrane of the mother cell invaginates and forms a layer around the developing spore, forming two membrane layers

Different types of flagellar arrangements

(a) monotrichous polar flagella - single flagellum (b) lophotrichous polar flagella - tufts of flagella emerging from same site; at 1 or both poles (c) amphitrichous polar flagella - tufts of flagella at both poles of cell (d) peritrichous flagella - flagella dispersed randomly over surface of entire cell

Conjugation

- "mating" process on gram-negative bacteria involving partial transfer of DNA from donor to recipient cells - can involve special (sex) pili - also a form of sexual recombination in ciliated protozoans

coccobacillus

- an elongated coccus - short & thick - oval-shaped bacterial rod

bacterial ribosome

- bilobed macromolecular complex - coordinates codons of mRNA with tRNA anticodons - constitutes peptide assembly site - sites of protein synthesis

Flagella

3 distinct parts: 1. filament helical structure composed of proteins 2. hook (sheath) filament inserted into curved hook anchored to cell by basal body 3. basal body stack of rings anchored through the cell wall to the cytoplasmic membrane + outer membrane

Label the image to assess your knowledge of bacterial cell structure

ALL bacteria possess: - a cell membrane - a chromosome (nucleoid) - ribosomes - cytoplasm SOME have EXTERNAL: - capsule - S layer - outer membrane - cell wall - fimbriae - flagella - pili SOME have INTERNAL: - inclusions - cytoskeleton - plasmids

True or False: Bacteria are larger than human cells

Bacteria are much smaller than eukaryotic cells

Which of the following is true of biofilms? - They can lead to systemic infections. - They pose no risk to the health of hospital patients. - They exhibit the same gene. - None of these answers are correct.

Bacteria exhibit a unique pattern of gene expression when in a biofilm, resulting in new growth characteristics. Biofilm bacteria can adhere to medical equipment used in patient care, such as a catheter, leading to the potential possibility of entering the patient's body and causing a systemic infection

Choose the bacterial appendage whose only role is to enable bacteria to stick to one another, to inanimate surfaces, and to host cells. Pili Fimbriae Flagella Axial filaments Cell wall

Bacterial fimbriae enable bacterial cells to stick to one another to aggregate and to stick to inanimate surfaces as well as to cells in their host.

Choose the term that best describes how bacteria respond to chemical attractants

Chemical attractants inhibit tumbles, enabling bacteria to make faster progress toward the stimulus chemical attractants inhibit tumbles. This maintains the runs (with flagella rotating counterclockwise) and enables the bacteria to make more progress toward a chemical stimulus

The differential stage of the Gram stain is the application of _____. crystal violet ethanol iodine safranin

Ethanol is the first step in the staining process that shows differences between the two types of bacteria. After its application, the gram-positive bacteria will be purple, and the gram-negative bacteria will be colorless

Gram-positive bacteria have flagella with four basal body rings, while those of gram-negative bacteria have only two

False

True or False: The thinner peptidoglycan layer of gram-positive bacteria allows the crystal-violet-iodine complex to leave the cell

Gram-positive bacteria have a thicker peptidoglycan layer that traps the crystal-violet-iodine complex inside the cell

Label the image to test your understanding of differences in gram-positive and gram-negative cell structure

Gram-positive cell walls (left) - thick layer of peptidoglycan - no outer membrane - contain teichoic acids. Gram-negative cell walls (right) - thin layer of peptidoglycan - outer membrane with - porins + lipopolysaccharides

True or False: All bacteria can be classified as either gram-positive or gram-negative

Some bacteria are classified as acid-fast, and others lack cell walls completely

True or False: The presence of flagella can be determined by a Gram stain

Special stains are needed to visualize flagella.

Move the correct terms into the empty boxes to complete the concept map

The current taxonomic system is comprised of 3 domains: Bacteria, Archaea & Eukarya -members of the Bacteria domain are unique in that they possess peptidoglycan-based cell walls

If the Gram's iodine step was skipped in this technique, what would likely be seen under the microscope? All cells would appear colorless. Most cells would appear purple. Most cells would appear red/pink. Most cells would appear blue.

The iodine forms a complex with the purple dye molecules, helping it stick in the thick gram-positive cell wall. Without it, the alcohol would most likely wash the crystal violet from all cells, and they would stain pink/red in the last step

A major component of gram-negative outer membranes, lipopolysaccharide can stimulate shock and fever and is referred to as: phospholipid lipopolysaccharide exotoxin glycosphingolipid

The outer membrane of gram-negative envelopes contains lipopolysaccharide, also known as LPS. The lipid portion of lipopolysaccharide can cause fever and shock and is also known as endotoxin.

The term used to describe a gently curved bacillus (rod) is: coccobacillus spirochete vibrio streptobacillus

Vibrio is the term used to describe a gently curved rod-shaped bacterium

bacterial species

a collection of bacterial cells that share an overall similar pattern of traits different from other groups of bacteria

Periplasmic Flagella

also called axial filament - type of flagellum (endoflagellum) that lies in the periplasmic space of spirochetes - responsible for locomotion

Microenvironments are created within the biofilm based on - All of these. - oxygen gradient. - pH gradient. - nutrient concentration

availability of gases such as oxygen, nutrient concentrations, and pH levels all can vary within the biofilm, leading to the recruitment of specific bacteria that can grow under these conditions

True or False: Bacteria are only visible with an electron microscope

bacteria are visible with the light microscope

Mycoplasmas

bacteria that naturally lack a cell wall - cytoplasmic membrane stabilized by sterols + resistant to lysis - pleomorphic cells; very small 0.1 to 0.5 nm - filamentous or doughnut shape - NOT obligate parasites; can be grown on artificial media - most important species: Mycoplasma pneumoniae; adheres to epithelial cells in lung

pleomorphism

cells of a single species to vary in shape and size - due to individual variations in cell wall structure caused by nutritional or slight genetic differences - reaches an extreme in the mycoplasmas picture: Rickettsia rickettsii

Biofilm

- complex association - arises from a mixture of microorganisms growing together on the surface of a habitat - complicate infections

Glycocalyx

- filamentous network of carbohydrate-rich molecules - coats cells via repeating polysaccharide units (may or may not include protein) (a) Slime Layer: loose shield; easily washed off; protects from loss of water + nutrients (b) Capsule: thick structured layer; bound more tightly; associated with virulence

Thiomargarita namibiensis

- largest non-eukaryote bacterial species - 100 to 750 mm (3/4 mm) E. coli

peptidoglycan

- macromolecule in cell walls - repeating framework of long glycan (sugar) chains cross-linked by short peptide (protein) fragments - make cell wall rigid

bacterial inclusion bodies

- or inclusions - inert body in cytoplasm - store nutrients - storage compartments

Drag the images to their corresponding class to test your ability to identify the various arrangements of cocci

- patterns of division & attachment can influence how a number of bacterial cells are arranged with respect to one another cocci can exist in: - pair of cells(diplo-) - groups of 4 (tetrads) - chain of several cells (strepto-) - irregular clusters (staphylo- or micro-) - cubical packets: 8, 16, or more cells (sarcina)

Fimbriae

- short, numerous surface appendage on some bacteria - provides adhesion but NOT locomotion - bristlelike fibers; small (a) Escherichia coli (b) E. coli

Gram-Negative Cell Wall

- single, thin sheet of peptidoglycan - 1 to 3 nm thick - greater flexibility and sensitivity to lysis

spirillum

- slightly curled bacterial cell - spiral-shaped cylinder - rigid helix (like a corkscrew) - external flagella Aquaspirillum

bacterial endospore

- small, dormant, resistant derivative of a bacterial cell - germinates into vegetative cell - bacterial genera Bacillus & Clostridium are typical sporeformers -- contain deadly pathofens

spirochete

- spiral-shaped bacterium - coiled; resembles spring - endoflagella - flexes as it moves

Gram-Positive Cell Wall

- thick, homogenous sheath of peptidoglycan - 20 to 80 nm in thickness - tightly bound acidic polysaccharides (teichoic acid + lipoteichoic acid) teichoic acid - polymer of ribitol or glycerol (alcohols) & phosphate - embedded in the peptidoglycan sheath lipoteichoic acid - attached to lipids in cytoplasmic membrane

Place the images in the correct order to assess your knowledge of the Gram stain procedure

1) addition of crystal violet, where both cell types take up the purple dye 2) Gram's iodine, which complexes with the purple crystal violet molecules 3) alcohol is added and removes the purple dye molecules from the thin peptidoglycan layer of the gram-negative cells only 4) safranin is applied to stain the colorless gram-negative cells

Drag the images to their corresponding class to test your understanding of bacterial cell shapes

1) coccus - spherical cells 2) bacillus - elongated cylindrical cells - rod-shaped 3) curved variations vibrio spirochete spirillum

cell envelope

complex boundary structure surrounding a bacterial cell bacterial cytoplasmic membrane typically phospholipid and proteins -- metabolic functions gram-negative envelope - outer membrane, cell wall, cytoplasmic membrane - stain red (safranin counterstain) - thinner cell walls - wide periplasmic space - outer membrane contain lipopolysaccharide (LPS) - LPS toxic to mammalian hosts gram-positive envelope - cell wall, cytoplasmic membrane - stain purple - thick cell walls of peptidoglycan and acidic polysaccharides

bacillus

cylindrical bacterial cell - rod; longer than it is wide Lactobacillus bulgaricus

Which of the following structures leads to reversible binding of bacterial cells to a surface? - spike proteins - fimbriae and flagella - fimbriae - flagella

fimbriae and flagella presence of flagella, fimbriae, and other bacterial cell surface structures allow for initial attachment of cells to a surface to commence biofilm formation.

Classification Systems for Bacteria and Archaea

formally classified by: - phylogenetic relationships - phenotypic characteristics

palisades arrangement

formed when cells of a chain remain partially attached after division - this hinge area can fold back, creating a side-by-side row of cells picture: Corynebacterium diphtheriae

How long can spores survive? 20 years 1 year Millions of years 2 months

longevity of bacterial spores verges on immortality.

sporulation

process of spore formation - depletion of nutrients (carbon/nitrogen source) is stimulus for a vegetative cell to begin endospore formation - process takes about 10 hours

coccus

spherical-shaped or ball-shaped bacterial cell Deinococcus

stereotype

subdivision of a species or subspecies into an immunologic type - based on antigenic characteristics - stimulate a distinct pattern of antibody (serum) responses in their hosts because of distinct surface molecules

In the next phase of spore formation, _____ enters the cortex and _____ leaves the cortex. calcium, water peptidoglycan, cell membrane water, calcium protein, lipids

the next phase of spore formation, calcium enters the cortex and water leaves the cortex

A vegetative cell is a frozen cell. a non-diving bacterial cell. a bacterial cell with an impervious coating. a metabolically active cell.

vegetative cell is a metabolically active and dividing cell

Archaea

- prokaryotic - single-celled

A unicellular microorganism was recovered from a hot spring (95oC) in Wyoming. The cells lack a nucleus, have a cell wall that lacks peptidoglycan, and have 70S ribosomes. Analysis of the plasma membrane reveals that the lipids contain long-chained branched hydrocarbons with ether linkages. Please choose the group in which this organism would be classified, based on the description provided Protist Archaea Bacteria Fungi

Archaea are unicellular prokaryotes. Unlike bacteria, they do not have peptidoglycan in their cell wall, but instead have a different polysaccharide. They also differ in membrane composition from bacteria, having membrane lipids with long branched hydrocarbons joined by ether linkages. Many of the archaea live in extreme environments. This one would be described as a hypertheromphile, based on its growth at 95oC.

Choose the component that provides for a stronger cell wall structure in gram-positive cells, compared to gram-negative cells Thick peptidoglycan layer Lipopolysaccharide Outer membrane Teichoic acids Phospholipids

It is the thickness of the peptidoglycan layer that makes gram-positive cell walls stronger than gram-negative cells walls. The teichoic acids in gram-positive cell walls do not significantly contribute to the strength of the cell wall. Gram-positive cells do not have an outer membrane, lipopolysaccharide or phospholipids

Choose the substance or condition that triggers sporogenesis among endospore-forming bacteria. Lack of water Presence of toxic chemicals Ultraviolet light exposure Excess heat Nutrient depletion

Sporogenesis (endospore formation) is triggered within a vegetative cell by nutrient depletion, particularly the depletion of carbon or nitrogen

Choose the division that includes the archaea (archaebacteria) Gracilicutes Firmicutes Temericutes Mendosicutes Actinobacteria

The archaea (archaebacteria) are classified in the Mendosicutes division which includes prokaryotes that have unusual cells walls that lack peptidoglycan and have unusual nutritional habits

appendages

accessory structures that sprout from the surface of bacteria divided into 2 major groups: - provide motility (flagella, axial filaments) - enable adhesion (fimbriae, pili)

During bacterial conjugation, DNA can be transferred from the donor cell to the recipient cell through which structure? Pilus Fimbria Flagellum Axial filament

DNA can be transferred through a pilus (pleural - pili) during bacterial conjugation.

To find listings and charts of biochemical tests that can be used to identify unknown bacteria, you could use: Bergey's Manual of Determinative Bacteriology Bergey's Manual of Systematic Bacteriology Bergey's Manual of Genotypic Analysis Bergey's Manual of Bacterial Typing

There are two different Bergey's manuals. The Bergey's Manual of Determinative Bacteriology provides information on identifying prokaryotes based on phenotypic (morphology, biochemical) characteristics. This would be the most useful for finding information on how to identify unknown bacteria. Bergey's Manual of Systematic Bacteriology provides information on prokaryotic evolutionary relationships based on rRNA sequencing information and phenotypic traits. While comprehensive, this manual is of less use from the practical standpoint of identifying unknown bacteria.

True or False: Biofilms are often more sensitive to antibiotics.

Biofilms are often impervious to antibiotics

True or False: Biofilms typically do not develop on healthy tissue

Biofilms tend to accumulate on damaged tissues

what general type of stain is used to separate types of bacteria based on their cellular structures? simple acidic negative differential

Differential staining techniques can be used to identify different types of bacteria, based on structures like their cell wall or the presence of endospores

When is sporulation initiated by spore-forming bacteria? As a normal part of cellular growth When the organism is exposed to sunlight When nutrients are depleted or conditions become adverse When the organism is placed in a hypertonic solution

Endospore-forming bacteria begin the process of spore formation (sporulation) when nutrients are depleted or conditions become adverse

Which term refers to the arrangement of bacilli in side-by-side rows?

Palisade Palisade arrangement of bacilli appears as side-by-side rows of cells

Rod-shaped bacteria are never gram-positive or gram-negative. are all gram-negative. can be either gram-positive or gram-negative. are all gram-positive.

Rod-shaped bacteria can be gram-positive, gram-negative, or acid-fast

The term used to describe a cluster of circular bacteria is _________. vibrio staphylococci streptococci streptobacilli

Staphylococci is the term used to describe a cluster of spherical bacteria

Which of the following diseases is NOT caused by a spore-forming bacterium? Anthrax Strep throat Tetanus Botulism

Streptococci do not form spores, whereas Bacillus anthracis, Clostridium tetani, and Clostridium botulinum are all members of spore-forming genera.

branching filaments

Streptomyces

A spirochete moves in a screw-like manner that is mediated by axial fibrils located in the cell's periplasmic space

True

Spirillum is a genus of spiral-shaped bacteria that move by flagella

True

True or False: Endospores function in the reproduction of bacterial genera such as Bacillus and Clostridium

While endospores are produced by these genera, they do NOT function in reproduction because no increase in cell number occurs. Instead, they are structures aimed at ensuring survival

oxygen usage

aerobic: use oxygen in metabolism; final e- acceptor in ETC is oxygen anaerobic: do NOT use oxygen in metabolism; final e- acceptor in ETC is inorganic molecule facultative: may or may not use oxygen in metabolism; NOT obligate

Which of the following conditions need to be suitable for bacteria to grow? pH Osmotic pressure Temperature All of these are examples of conditions that need to be suitable for bacterial growth

all of the conditions need to be suitable for bacteria to grow

When spore formation begins, the vegetative cell is referred to as the ________. parent cell haploid cell father cell mother cell

in endospore formation, the vegetative cell is referred to as the "mother cell."

variant forms within a species

include: - strains: set of descendants cloned from a common ancestor that retain original characteristics; any deviation from original is a different strain - subspecies: bacteria of the same species that have differing characteristics; also known as types

medical identification of pathogens

informal system of classification based on: - Gram stain - morphology - biochemical reactions - metabolic requirements

Which of the following surfaces have nutrients available that encourage the development of biofilms? - moist abiotic surfaces - dry abiotic surfaces - biotic surfaces such as plant and animal tissue - moist abiotic surfaces and biotic surfaces such as plant and animal tissue

moist abiotic surfaces and biotic surfaces such as plant and animal tissue Abiotic surfaces immersed in fluid can attract and concentrate nutrients for the growth of biofilm microorganisms, while biotic surfaces can themselves serve as nutrient sources for the microbes.

The primary function of flagella is for ______ - transferring DNA to other cells - attachment - maintaining cell shape - motility

motility flagella provide motility for bacteria, whereas other external structures like pili, fimbriae and the cell envelope assist in the other functions listed.

Why must fresh cells be used when performing a Gram stain? Old cells may not Gram stain properly. Fresh cells do not smell as badly as older cells. All of these are reasons why fresh cells must be used for Gram staining. As cells age, they won't stick to the slide.

old cells may not Gram stain properly

Biofilms are found - on the walls of swimming pools. - on a variety of surfaces including shower curtains, the walls of swimming pools, and teeth. - on shower curtains. - on teeth.

on a variety of surfaces including shower curtains, the walls of swimming pools, and teeth. Biofilms are universal and found almost everywhere

When ethanol is applied correctly, gram-positive cells appear ____ and gram-negative cells appear _____. purple ; colorless purple ; pink/red colorless ; purple pink/red ; purple

only gram-negative cells lose their purple color after ethanol is used as a decolorizer

Which of the following is considered an "adverse condition" by most bacteria? all of these Complex media Temperature of 45 degrees Celsius pH = 4

pH of 4 is very acidic and not hospitable for most bacteria