Microbiology Quiz 2/ Exam 2

Outer and Inner membrane vs plasm and cytoplasmic membrane

Gram positive bacteria have and outer wall and cytoplasmic membrane while gram negative bacteria have and outer membrane, cell wall and then cytoplasmic membrane.

What are protoplasts?

Gram(+) cell stripped of it's cell wall and stays in a dormant position in an osmoticly stable area of the body, one of the antibiotic resistant

What is the action of Penicillin?

Penicillin interferes with peptidoglycan synthesis by binding to Penicillin binding protein (PBP) which facilitates cross linkage of adjacent tetrapeptide chain.

What are pilin and flagellin and what role do they play in the body?

They are the proteins that make up pili and fimbriae and flagellum. They are PAMPs that cause the body to have an immune response.

How do bacteria membranes differ from eukaryotic membranes?

They don't have cholesterol.

What are integral proteins? Examples?

Integral proteins: -extend into through the lipid bilayer -typically are trans membrane proteins/ permeases (involved in transport)

What is the role of the 3rd amino acid in tetra peptide tail?

It links to the 4th residual amino acid of the adjacent chain.

What is the monotrichous flagella arrangement and give one example.

One hair, single polar, attached to one end Example: pseudomonas aeroginosa

Glycocalyx functions

Passive defense barrier 1) protection: due to it's anti-phagocytic nature (virulence factor) by having a similar chemical composition as host cells or by being slippery in nature. 2)protects cell from drying; due to it's functional capacity to bind and retain water molecules (hydrophilic nature) 3) plays critical role in colonization during initial attachment to their host surface due to sticky nature

What are PAMP's?

Pathogen associated molecular patterns: microbial molecules that trigger the bodies response. Examples include: peptidoglycan, lipopolysacchride, flagellin, and pilin.

What is the 3rd amino acid in the tetra peptide tail of a Gram positive cell wall?

Always L-lysine

What is self autonomous replication?

A plasmid can replicate independently of the chromosome

What are fimbriae?

A variation of pili, -fimbriae number varies (few to thousands); distributed throughout or have polar concentration. -aids in attachment to substrate as well as to one another. -harbors adhesin, either at the tip or all along its length. -made of pilin protiens.

What are adhesins, what do they do? Where are they found?

Adhesins are a surface lipoprotein and glycoprotein molecules called ligados that enable them to bind to complementary receptors on host cells. They are found on fimbriae, flagella and glycocalyces of bacteria.

What is unique about the Bordetella sps adhesins

Bordetella (aka whopping cough) has more than one type of adhesin.

Glycocalyx composition

Composed mainly of polysaccharides; in some, polypeptides as in Bacillus anthracis

E.coli O157:H7 vs E. coli K12

E.coli O157:H7 is present in cattle intestine while E. coli K12 is present in human intestine. Contamination of E.coli O157:H7 indicates fecal matter contamination and will be out competed in a healthy immune system but if it colonizes it will secrete a toxin that shuts down kidney function.

What is the composition of the cross bridge (aka connecting chain) ? And what is PBP?

It is a peptide inter bridge made of either a short chain of amino acids or bonded to one another. It links the 3d residue of the one chain to the 4th residual amino acid of the adjacent chain. There is a wide variation in bridge amino acid sequence. PBP is the Penicillin binding protein that facilitate the cross ringing that penicillin blocks.

What is special about Streptococcus mutans (S. mutans) capsule?

It is in dental plaque and colonized on the tooth surface and ferments sugar and acid waste and destroys the tooth.

What does Lysozyme do to the cell wall?

It is present in tears, saliva and body fluids. It breaks the bond between NAG and NAM (backbone structure)

Dynamic vs static role of Plasma membrane

not a static structure, semi permeable but monitors what goes in and out, needs a stable environment for metabolism to produce ATP/energy. -acts as a selective barrier; monitors flow in both directions -helps maintain constant, appropriate internal environment

What is the lophotrichous flagella arrangement and give one example.

A bunch; 2 or more flagella at one pole of the cell. Example: helicobacter pylori

What does Vancomycin do to the cell wall?

It binds to the 4th amino acid of the tail and prevents cross bridging.

Can capsule polysaccharides be used as vaccines?

"No question" but I think so...

Plasma Membrane rigidity in eukaryotes and Mycoplasma cell

Cholesterol

Identify the accessory structures of bacteria cells

Chromosome, plasmids, ribosomes, inclusions

Bacterial plasma membrane

- is thin structure that lies inside the cell wall, encloses cytoplasm -defines the external boundary of cell -plasm membrane components: -prokaryote pm consists of: phospholipid, proteins, glycoprotiens; no cholesterol, makes the membrane more fluid and less ridged and more frágil but is in turn protected by ridged cell wall structure. -Eukaryotes have cholesterol -plasma membrane has dynamic role: 1) acts as selective barrier; monitors flow in both directions 2) helps maintain constant, appropriate internal environment.

What are the functions of teichoic acids?

-It binds and regulates (+) charged ion movement into and out of cell. - they furnish attachment sites for many bacteriophages which are viruses that infect bacterial cells -provides antigenic specificity. We don't have teichoic acid and it triggers our immune system.

What are components of the outer membrane (aka Lipopolysaccahride layer) and what do they do?

-Lipopolysaccharides -Lipoproteins -Phospholipids -Integral Proteins -Porin Functions: -provides gram (-) bacteria extra protection from antimicrobial agents. -has the ability to "pump out" antimicrobial preparations; gram(-) bateria's and resistance.- Has 'porin' molecules interspersed throughout which allow substances to pass through to periplasm (transport tunnels)

What does Gram negative cell wall consist of ?

-Periplasm and periplasmic space -A few layers of peptidoglycan -An outer membrane It does not have teichoic acid.

What is the peptidoglycan like in a gram negative cell wall?

-Thin layered, suspended in the periplasmic space -Linked to outer membrane (via lipoproteins); stably anchored -Possess typical peptidoglycan. Structure with 2 changes: 1) The 3rd amino acid of the tetrapeptide tail is diaminopimelic acid (DAP). 2) The cross bridge is direct unlike Gram (+)

What are endospores?

-are refractile structures; commonly made by the Gram(+) bacteria, example: clostridium and bacillus sps -produced in response to unfavorable conditions -single bacterium makes one spore (for survival); spores are dormant structures and highly resistant to harsh environments. -spores contain DNA, RNA, ribosomes and dipicolinic acid accompanied by increased Ca ions (essential for resuming metabolism later) -spore diameter: can be the same, smaller, or larger than mother cell. -spore location: can be terminal, sub terminal, central -has a keratin cell wall.

Endotoxin

-lipid A portion of outer membrane of LPS or Gram (-) species -released upon cell damage and cell wall breakage -all endotoxins produce the same signs and symptoms, though to different degrees (irrespective of microbe) -Symptoms include DIC: that leads to blocked arteries, tissue necrosis, hemorrhage because all clotting factors are used up. Also, fever, vasodilation, and sudden drop of blood pressure, many vital organs are compromised. Causes alteration of vital organ function. -Endotoxins have the same mode of action, irrespective of the species.

What are bacterial chromosomes?

-they are single, circular, double stranded DNA molecules (supercoiled); with the exception of choleara. -anchored to plasma membrane; confined in nucleoid area.

What are bacterial plasmids?

-they are small, extrachromosomal DNA molecules. -self replicating units -are not required for metabolism/ survival under normal conditions but provide selective advantage to cell if present. -all housekeeping genes are in chromosomal DNA, not in plasmid Functions: -plasmids carry genes for activities such as: antibiotic resistance and toxins production

What are the different types of plasmids?

1) Fertility plasmid: codes for the sex pili (F pili) and is involved in conjugation process. 2) Resistance plasmid: carry resistance genes for antimicrobial agents (antibiotics and heavy metals) -have both origin of transfer gene as well as resistance genes. - are self transmissible plasmids (in contrast to others which are non-self transmissible) 3) Bacteriocin plasmid: carry genes for the bacteriocin (kills other bacteria that don't carry bacteriocin plasmids. -role of the bacteriocin toxin is that it kills other bacteria that don't carry bacteriocin plasmids. 4) Virulence plasmid: carry genetic information, instructions for the structures, enzymes or toxins (virulence structures) that enable a bacterium to become pathogenic. For example, E. coli causes diarrhea only when it has a plasmid that codes for certain toxins.

What are the different types of inclusion bodies?

1) Metachromatic granules (aka volutin) -represents polyphosphate granules -can be degraded and used as iP (inorganic phosphorus) source for, ATP synthesis, teichoic acid, phospholipids, nuclei can acid. -stains red with some blue (methylene blue) -characteristic feature of Corynebacterium diptheriae (pleomorphisis is the result of accumulation of granulas. 2) Polysaccharides granules -includes starch and glycogen -they are storage depot for carbon and energy source -clinically useful for chlamydia sps identification (sometimes id-ed by polysaccharide granules 3)Lipid inclusion -represented by inclusion of poly-hydroxy butyrate acid; surrounded by monolayer membrane -like polysaccharide, they are carbon and energy storage polymer

Explain 2 mechanisms by which the capsule aids in protecting pathogenic bacteria from host defense system.

1) by having a similar chemical composition as host cells 2) by being slippery. nature.

What is the importances of the O-polysaccharides aka O-antigen?

A repetitive glycan polymer contained within an LPS is referred to as the O antigen, O polysaccharide, or O side-chain of the bacteria. The O antigen is attached to the core oligosaccharide, and comprises the outermost domain of the LPS molecule. The composition of the O chain varies from strain to strain. O antigen is exposed on the very outer surface of the bacterial cell, and, as a consequence, is a target for recognition by host antibodies.

What are pili?

Also called sex pili or F pili or conjugation pili; shorter than flagella and responsible for the exchange of genetic material. There are usually 1-10 sex pili per cells. It aids in joining cells of opposite mating types during conjugation process and is responsible fro exchange of genetic material between cells. There is no sexual reproduction yet but they evolve through conjugation. -made of pilin protiens.

What is the concept of of antigenic specificity?

Antigenic specificity is the ability of the host cells to recognize an antigen specifically as a unique molecular entity and distinguish it from another with exquisite precision

What is the concept of attractant and repellent?

Attractant: example: nutrient, the cells move toward it, more runs of longer duration, positive taxis and less tumbles. Repellent: example: toxins, heat, cells move away from it, negative taxis, more tumbles

Explain how motility in bacteria is accomplished.

Bacteria motility is primarily accomplished via flagella, a long, semi ridged and filamentous appendage that acts like a spinning motor, propels cell in forward direction. Bacteria can also use fimbriae via a process similar to pulling an object with a rope.

What is a lipoprotein?

Bacterial lipoproteins are a set of membrane proteins with many different functions. Due to this broad-ranging functionality, these proteins have a considerable significance in many phenomena, from cellular physiology through cell division and virulence. Here we give a general overview of lipoprotein biogenesis and highlight examples of the roles of lipoproteins in bacterial disease caused by a selection of medically relevant Gram-negative and Gram-positive pathogens: Mycobacterium tuberculosis, Streptococcus pneumoniae, Borrelia burgdorferi, and Neisseria meningitidis. Lipoproteins have been shown to play key roles in adhesion to host cells, modulation of inflammatory processes, and translocation of virulence factors into host cells. As such, a number of lipoproteins have been shown to be potential vaccines. This review provides a summary of some of the reported roles of lipoproteins and of how this knowledge has been exploited in some cases for the generation of novel countermeasures to bacterial diseases.

Concept of slime layer vs capsule with examples

Capsule: glycocalyx (uses stain via acid) is well structured and firmly attached to cell wall. Composed of organized repeating units of organic chemicals firmly attached to cell surface. Example: Staphylococcus Slime layer: secreted porti ; loose and water soluable Example: Bacteriods (in feces)

What does Lipid A cause when released?

Causes DIC Disseminated Intravascular Clotting that leads to blocked arteries, tissue necrosis, hemorrhage because all clotting factors are used up. Also, fever, vasodilation, and sudden drop of blood pressure, many vital organs are compromised. Causes alteration of vital organ function.

How does cranberry juice work with UTIs

Components in the juice interfer with the adhesive to host cell so that it is excerpted out to the body with out alteration. It disrupts bonding between adhesive and sugar molecule.

How are Cornybacterium and Chlamydia detected in clinical samples?

Cornybacterium: metachromatic granules (a type of inclusion body) can cause pleomorphism making one side of the cell to swell up. Chlamydia: polysaccharide granules (a type of inclusion body) can be identified

What is the 3rd amino acid in the tetra peptide tail of a Gram negative cell wall?

Diaminopimelic Acid (DAP) a modified lysine

What is the role of Dipicolinc acid in endospores?

Dipicolinic acid (pyridine-2,6-dicarboxylic acid or PDC and DPA) is a chemical compound which composes 5% to 15% of the dry weight of bacterial spores. It is implicated as responsible for the heat resistance of the endospore. ... Dipicolinic acid forms a complex with calcium ions within the endospore core.

What is an endoflagella and its significance in pathogenic microbes? Give 2 examples of pathogenic bacteria with endoflagella.

Endoflagella is a flagella that is inside a membraneous lining, technically not present in the cell membrane. It is present in spirochete. There is an outer sheath (membrane). The sheath is anchored at one end and spirals around cells. It uses a corkscrew motion to drill into viscous tissues of their host. Examples: Treponema pallidum (causes syphilis) Borrelia burgdorferi (causes lyme disease)

What is the role of Ca ions in endospores?

Essential for resuming metabolism later and it is implicated as responsible for the heat resistance of the endospore. ... Dipicolinic acid forms a complex with calcium ions within the endospore core. This complex binds free water molecules, causing dehydration of the spore. As a result, the heat resistance of macromolecules within the core increases

Identify the appendages of bacterial cells.

Flagella, fimbriae, pili, endoflagella

What is the structure of flagella?

Flagellum has 3 basic parts: 1)Filament: long, hollow, "whip like" structure of constant diameter that extends out into the cell's environment. It is composed of many identical globular molecules of a protein called flagellin (our bodies do not make this and it trigger's our body's defense system. 2) Hook: wider part to which filament is attached, made of a different protein , not flagellin. 3) Basal body: anchors the flagellum to the cell wall and membrane, it includes a central rod inserted into a series of rings.

What are spheroplasts?

Gram (-) cell partially stripped of it's cell wall, always some reside on cell wall on its surface.

What is the peritrichous flagella arrangement and give one example.

Hair all over perimeter, flagella distributed over entire surface Example: E. coli

What is streptococcus pyogenes' capsule composition

Has a hyaluronic acid (HA) capsule. (HA) is a component of connective tissue and tricks the body into thinking it belongs.

Identify a bacteria with lophotrichous arrangement of flagella and it's importance to the pathogenesis.

Helicobacter pylori: helps to invade across the mucosal coating of the intestinal epithelium.

Concept of direct and indirect bridging;

In Gram positive cells a peptide interbridge ("the bridge") connects the tetra peptide chain of amino acids ("the tail"). In Gram Negative bacteria the cross bridge is direct unlike Gram positive bacteria.

Mycobacterium species

Include bacteria that causes TB. Has mycolic acid that forms the major component of the cell wall of mycolata species. Mycolic acids impart M. tuberculosis with unique properties that defy medical treatment. They make the organism more resistant to chemical damage and dehydration, and limit the effectiveness of hydrophilic antibiotics and biocides.[1] Mycolic acids also allow the bacterium to grow inside macrophages, effectively hiding it from the host immune system.

What are inclusion bodies?

Inclusion bodies, sometimes called elementary bodies, are nuclear or cytoplasmic aggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication in a bacterium or a eukaryotic cell and usually consist of viral capsid proteins.

Recall some situations in which lipid A is released from cells.

Lipid A is released during lysis due to: 1)antibiotics 2) MAC (membrane attack complex) mediated cell destruction 3)cells are phagocytosis and destroyed by immune cell defense

What are specific features associated with lipopolysaccharides?

Lipopolysaccharides (LPS), also known as lipoglycans and endotoxins, are large molecules consisting of a lipid and a polysaccharide composed of O-antigen, outer core and inner core joined by a covalent bond; they are found in the outer membrane of Gram-negative bacteria, and elicit strong immune responses in animals.

Fluid Mosaic Model

Membrane resembles a sea of lipids with a mosaic of embedded proteins and attached sugar molecules Lipids: arranged as bilateral, composted mainly of phospholipids Proteins: are in motion laterally: grouped into classes, Integral proteins: -extend into through the lipid bilayer -typically are trans membrane proteins/ permeases (involved in transport) Peripheral proteins: -attached to inner or outer surface of membranes -functions as enzymes, scaffold, receptors etc

What are the functional role of adhesins in Neisseria sps and E. coli?

Neisseria gonorrhoeae have adhesins on its fimbriae that adhere to cells lining the urethra and vagina of humans. Thus this pathogen cannot affect other hosts. E.coli attaches to the mucous membranes of the intestine.

Are phospholipids present in periplasma?

No

Do LPS molecules play a role in attachment?

No

What is a unique feature of mycoplasma?

No cell wall either and natural exhibit of pleomorphism, smallest living organism and causes walking pneumonia,

Detailed structure of bacteria cell wall

Peptidoglycan: macromolecule and provides rigidity and mechanical stability, consists of back bone, tail and bridge. Backbone: linear polymer of repeat disaccharide units of alternating NAG and NAM linked by O-glycosidic linkage Tail: tetrapeptide composed of of alternating D and L amino acids, which attaches to NAM via a complex linkage. It minimizes tendency to form hélices and provides an extended "rigid peptide chain. Bridge (aka connecting chain): crosslink between parallel tetrapeptide side chains, made of either short chain of amino acids or bonded to one another, links 3rd residue of one chain to the 4th residual amino acid of the adjacent chain.

What are peripheral proteins? Examples?

Peripheral proteins: -attached to inner or outer surface of membranes -functions as enzymes, scaffold, receptors etc

What is Teichoic acid?

Polymer of sugar/glycerol phosphate with amino acid (D-alanine). It is covalently attached to NAM and unique to Gram positive bacteria.

Action of some membrane acting antibiotics and disinfectants (polymixin, alcohol and Lysol only)

Polymixin B: one of the components of 1st aid ointments. It binds to phosolipids and destabilizes the membrane. Very toxic to kidneys. Never given outside of topical use and can also disrupt human cells but at low concentration bacteria are more susceptible because our cells have cholesterol Alcohol: used at 70% concentration, 100% would not work, it's an organic compound and works the same ways as Lysol. Lysol: trade mark of phenol based compounds, which dissolves the lipid membrane proteins

What is bacillus anthracis capsule composition

Polypeptides: poly D. Glutamic acid

What is the chemical composition of ribosomes?

Ribosomes consist of two major components: the small ribosomal subunit, which reads the RNA, and the large subunit, which joins amino acids to form a polypeptide chain. Each subunit is composed of one or more ribosomal RNA (rRNA) molecules and a variety of ribosomal proteins.

What are Runs and Tumbles?

Run: an uninterrupted unidirectional movement Tumbles: sudden stop and bacteria rolls over, several times, changes the direction and resumes run.

What is taxis (chemotaxis)?

Sensin and responding to stimuli.

What are ribosomes?

The bacterial ribosome is a cytoplasmic nucleoprotein particle whose main function is to serve as the site of mRNA translation and protein synthesis. The ribosome has a mass of about 2.5 MDa, with RNA accounting for 2/3 of the mass. It consists of two subunits denoted 30S (small subunit) and 50S (large). The subunits are a preferred target site of some antibiotic action

Backbone units and role of NAM in tetraeptide tail

The units are made of alternating NAG (N-acetylglucosamine) and NAM (N-acetylmuramic acid) linked by O-glycosidic linkage of tetra-peptide chain of amino acids that extend from NAM.

Recall the types of teichoic acids?

There are 2 types of Teichoic acids: 1) Lipoteichoic acid: spans the thick peptidoglycan layer and is attached to plasma membrane lipids. 2)Wall teichoic acid: confined to the peptidoglycan layer

Plasma membrane transport process

Transport systems: mechanism that facilitates small molecules to enter cell across the normally impermeable membrane Role of transport system: A. To bring in nutrients B. Expel waste products and substances harmful to the cell (efflux) C. Secreation -secretion of selective protein molecules which are structure also components -toxins which are virulence factors -secretion of enzymes - breaks down large substances fro absorption Example: amylase breaks down starch to macron to smaller glucose

What is the amphitrichous flagella arrangement and give one example.

Tuft of flagella at each end of the cell. Example: spirilla, spirillum volutans.

What are phages?

Viruses that infect bacterial cells.

Are LPS molecules the target for antibodies?

Yes

How are bacterial ribosomes different from eukaryotic ribosome?

the ribosomes of bacteria are smaller than eukaryotic ribosomes which are (70 S vs 80S) S= Svedberg unit.