[1S] UNIT 1.2 Bacterial Cell Structure Flashcards by JULIA CASSANDRA RECCION

PROKARYOTES VS EUKARYOTES: SIZE

0.4-2 um

Prokaryotes

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PROKARYOTES VS EUKARYOTES: SIZE

10-100 um

Eukaryotes

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PROKARYOTES VS EUKARYOTES: NUCLEAR BODY

Nucleoid in the cytosol

Prokaryotes

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PROKARYOTES VS EUKARYOTES: NUCLEAR BODY

Enclosed in a membrane

Eukaryotes

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PROKARYOTES VS EUKARYOTES: GENOME

Circular dsDNA (double stranded DNA); In the nucleoid, mesosome

Prokaryotes

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PROKARYOTES VS EUKARYOTES: GENOME

Multiple, linear DNA; In the nucleus

Eukaryotes

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PROKARYOTES VS EUKARYOTES: EXTRACHROMOSOMAL CDNA

Plasmids, Transposons, Episomes
*These are important in the antibiotic mechanism of the organism

Prokaryotes

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PROKARYOTES VS EUKARYOTES: EXTRACHROMOSOMAL CDNA

Mitochondria, Chloroplast

Eukaryotes

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PROKARYOTES VS EUKARYOTES: CELL DIVISION

Binary Fission

Prokaryotes

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PROKARYOTES VS EUKARYOTES: CELL DIVISION

Mitosis

Eukaryotes

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PROKARYOTES VS EUKARYOTES: CELL WALL

PRESENT (except in Mycoplasma and Ureaplasma)

Prokaryotes

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PROKARYOTES VS EUKARYOTES: CELL WALL

ABSENT (except in Fungi)

Eukaryotes

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PROKARYOTES VS EUKARYOTES: CYTOPLASMIC MEMBRANE

Present (phospholipids and protein)
No sterols present

Prokaryotes

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PROKARYOTES VS EUKARYOTES: CYTOPLASMIC MEMBRANE

PRESENT (phospholipids and sterols)

Eukaryotes

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PROKARYOTES VS EUKARYOTES: CELL ORGANELLES

Present
Absent

Eukaryotes
Prokaryotes

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PROKARYOTES VS EUKARYOTES: SITE OF ENERGY PROD

Cytoplasmic Membrane or Plasma Membrane

Prokaryotes

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PROKARYOTES VS EUKARYOTES: SITE OF ENERGY PROD

Mitochondria (powerhouse of the eukaryotic cell)

Eukaryotes

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PROKARYOTES VS EUKARYOTES: SITE OF PROTEIN SYNTHESIS

Free Ribosomes
Ribosomes (70S)

Prokaryotes

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PROKARYOTES VS EUKARYOTES: SITE OF PROTEIN SYNTHESIS

Rough ER
Ribosomes (80s)

Eukaryotes

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PROKARYOTES VS EUKARYOTES: MOTILITY

Flagella

Prokaryotes

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PROKARYOTES VS EUKARYOTES: MOTILITY

Flagella, Cilia, Pseudopod

Eukaryotes

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Bacterial cell is made up of

70% Water & 30% Carbohydrates, Proteins, Lipids, Enzymes

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Bacterial cell wall structures (2)

Cell envelope structures
Cytoplasmic structures

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● Consists of Cell Wall and Cell Membrane
● Some bacteria may also possess capsules and slime layers

Cell Envelope Structures

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● Outer membrane (gram-negative only) ● Cell wall (murein layer)

Cell Envelope Structures

CELL ENVELOPE: CELL WALL Contains a thick layer of peptidoglycan

Gram-positive

CELL ENVELOPE: CELL WALL Contains thin layer of peptidoglycan

Gram-negative

CELL ENVELOPE: CELL WALL Contains waxy substances (e.g. mycolic acids)

Acid fast

CELL ENVELOPE ○ Contains gel-like substances that capture nutrients ○ Contains enzymes needed for detoxification and degradation purposes

Periplasm

CELL ENVELOPE T/F: Periplasm is distinct in gram-negative

CELL ENVELOPE ○ Is the deepest layer of the cell ○ Contains proteins and enzymes that are vital to cellular metabolism ○ Serves as osmotic barrier

Cell Membrane

● Gives shape to the bacterial cell ● Provides protection

Cell Wall

3 types of cell wall

Gram (+), Gram (-) and Acid Fast

Main constituent of cell wall

Peptidoglycan or Murein

Cell wall consists of these 2 alternating disaccharides and are linked by pentapeptides

■ NAG (N-Acetylglucosamine) ■ NAM (N-Acetylmuramic acid)

● Responsible for pathogenicity ● Serves as a point of anchorage of flagella ● Responsible for antigenic characteristic of certain bacteria

Cell Wall

CELL WALL PATHOGENICITY prevents phagocytosis

M protein

CELL WALL PATHOGENICITY prevent digestion

Mycolic Acid

● Serves as the target of antimicrobial agents ● Responsible for staining characteristic of the cell

Cell Wall

GRAM (+) VS GRAM (-) CELL WALL Thick protective murein layer

Gram (+)

GRAM (+) VS GRAM (-) CELL WALL Thinner Murein Layer (Inner Peptidoglycan Layer)

Gram (-)

GRAM (+) VS GRAM (-) CELL WALL Presence of (Ribitol/Glycerol phosphate) Teichoic and Lipoteichoic acid (Glycerol Teichoic acid)

Gram (+) Cell Wall

GRAM (+) VS GRAM (-) CELL WALL Presence of Murein Lipoprotein

Gram (-)

GRAM (+) VS GRAM (-) CELL WALL No periplasm

Gram (+)

GRAM (+) VS GRAM (-) CELL WALL Periplasmic space

Gram (-) Cell Wall

GRAM (+) VS GRAM (-) CELL WALL Antigenic polysaccharide Presence of S-layer

Gram (+)

GRAM (+) VS GRAM (-) CELL WALL Outer layer: proteins, phospholipids, and lipopolysaccharides: - O-antigen - Core polysaccharide - Lipid A (endotoxin)

Gram (-)

GRAM (+) VS GRAM (-) CELL WALL Flagellum is provided only with two basal rings

Gram (+)

G(+)/G(-): Haemophilus influenzae, Neisseria gonorrhoeae and Bordetella pertussis

Gram (-) Cell Wall

Presence of phospholipids similar in the cell membrane

Gram (-) Cell Wall

Presence of Principal Proteins or Major Outer Membrane Proteins such as ○ Porin Proteins ○ Transmembrane Proteins ○ Peripheral proteins

Gram (-) Cell Wall

GRAM (-) CELL WALL span the outer membrane

Transmembrane Proteins

GRAM (-) CELL WALL responsible for transmembrane transport of molecules

Peripheral proteins

appear as WEAKLY GRAM POSITIVE

Acid Fast Cell Wall

Possess a waxy layer of mycolic acid bound to the cell wall ○ Seen in Mycobacterium, Nocardia

Acid Fast Cell Wall

Cell membrane of AF organisms are similar to other bacteria except that they possess _________ & ____________

Phosphatidylmannosides (PIM) and Lipoarabinomannan

ORGANISMS THAT LACK CELL WALL ○ Contains sterol in their cell membranes ○ Seen in various shape microscopically

Mycoplasma and Ureaplasma

ORGANISMS THAT LACK CELL WALL gram-positive and gram-negative cells that lose their cell walls ○ can grow in media supplemented with serum or sugar to prevent osmotic rupture of the cell membrane

L-forms

● Phospholipid bilayer with embedded proteins ● Composition: 30-60% Phospholipids and 50-70% Protein

Plasma / Cell Membrane

● For protection ● Osmotic barrier ● Site of energy production: electron transport chain

Plasma Membrane

● Chemical components: phospholipids and proteins ● No sterols present

Plasma Membrane

● Folded areas of the cell membrane ● Extensions of the cytoplasmic membrane

Mesosomes

● Site of enzymatic activity ● Point of attachment for nucleoid

Mesosomes

Capsule (organized) Slime Layer (unorganized)

Surface Polymers

● Generally composed of polysaccharides ● An organized material that is firmly attached to the cell wall

Capsule

○ Protects from toxic substances and desiccation ○ Promotes concentration of nutrients

Capsule

○ Promotes adhesion ○ Antiphagocytic factor ○ Antigenic (K antigen); (Vi antigen seen in S. typhi)

Capsule

Klebsiella pneumoniae Streptococcus pneumoniae Neisseria meningitidis Haemophilus influenzae

CAPSULE: Polysaccharide Containing

Bacillus anthracis

CAPSULE: Polypeptide D-Glutamic Acid Containing

Pasteurella multocida

CAPSULE: Hyaluronic Acid Containing

Unorganized layer and not firmly attached to cell wall

Slime Layer

Inhibits phagocytosis or aid in the adherence to host tissue or synthetic implants

Slime Layer

- Organisms capable of producing slime layer - Also polysaccharide containing

○ Staphyloccocus epidermis ○ Steptococcus mutans

Consists of a monomicrobic or polymicrobic group of bacteria housed in a complex polysaccharide matrix

Biofilm

The cells reach a critical mass that results in alteration in metabolism and gene expression

Biofilm

Why are biofilms important

● Often difficult to detect ● Resistant to desiccation ● Dissemination ● Tolerant to biocides

● Locomotory appendage of the bacterial cell ● Long filamentous appendages ● Organ for Locomotion/Motility

Flagella

Seen mostly in Gr(-) bacilli

Flagella

3 parts of flagella

filament, hook and basal body

seen in Vibrio

Sheathed Flagella

● Protein Composition: Flagellin ● Function: Allows the spread of infection ● Antigen: H Antigen (heat-labile)

Flagella

no flagella

Atrichous

has a singular flagellum on one end

Monotrichous

has multiple (tuft) flagella on one end of the bacterium

Lophotrichous

flagella is evenly distributed on both ends of the bacterium

Peritrichous

contains a single flagellum on both ends of the bacteria

Amphitrichous

3 flagellar stains

● Leifson ● Gray ● Fisher and Conn

FLAGELLA Motility is best observed at

25°C

Flagella is seen at 2 methods

Hanging Drop Method & Use of Semisolid Media

● Axial Fibril ● Spirochetes (cork-screw motility)

Periplasmic Flagella (Endoflagellum)

● Hairlike, protein structures (2um in length) ● Main purpose is for bacterial adherence and conjugation ● Non-motile, long hollow proteins

Pili

PILI Promotes bacterial adherence

Common/Somatic Pili/Fimbriae

PILI Allows genetic exchange between two bacterial cells

Sex Pili

● Escherichia coli ● Neisseria gonorrhoeae ● Neisseria meningitidis ● Pseudomonas aeruginosa ● Some Gr(+) organisms such as: Actinomyces, some Streptococci, and Corynebacteria

Fimbrae

Amorphous gel containing enzymes, granules, inclusions, genome

Cytoplasm

CYTOPLASMIC STRUCTURES Chromatin or nuclear body composed of a single circular DNA

Nucleoid

CYTOPLASMIC STRUCTURES Appear as free or attached to the cell membrane

Ribosomes

CYTOPLASMIC STRUCTURES

NUCLEOID RIBOSOMES ENDOSPORES TRANSPOSONS & PLASMIDS CYTOPLASMIC GRANULES

CYTOPLASMIC STRUCTURES Produced during harsh environmental conditions to protect itself against them, such as temperature change, dessication, high exposure to gamma radiation and chemical agents

Endospores

CYTOPLASMIC STRUCTURES Multilayered, small, dormant asexual spores

Endospores

CYTOPLASMIC STRUCTURES ● HIGHLY RESISTANT IN UNFAVORABLE CONDITIONS ● COMPOSITION: Dipicolinic acid calcium complex

Endospores

CYTOPLASMIC STRUCTURES ● Stained/Visualized by Fulton-Schaeffer Method ● Medically Important Genera with spores: ○ Bacillus ○ Clostridium

Endospores

“Jumping genes”

Transposons

DNA elements that are able to “JUMP” or TRANSPOSE from one chromosome or plasmid to another

Transposons

Function: Carry antibiotic resistance genes

Transposons

● Circular DNA elements ● Replicate independently from the chromosome

Plasmids

Carry genes that give the bacterium an advantage

Plasmids

Serve as food reserves (polysaccharides, lipids, polyphosphates)

Inclusion Bodies

INCLUSION BODIES Major storage material for Enterics

Glycogen

INCLUSION BODIES Principal storage material for Neisseria and Clostridium

Starch

INCLUSION BODIES seen in Bacillus and Pseudomonas

Poly-beta hydroxybutyrate

BACTERIA AND THEIR INCLUSION BODIES Much Granules

Mycobacterium tuberculosis

BACTERIA AND THEIR INCLUSION BODIES ● Babes Ernst Bodies ● Metachromatic Granules ● Volutin

Corynebacterium diptheriae

BACTERIA AND THEIR INCLUSION BODIES Halberstaedter Prowazek Bodies

Chlamydia trachomatis

BACTERIA AND THEIR INCLUSION BODIES Levinthal Cole Lillie Bodies

Chlamydia psitaci

INCLUSION BODIES contains sulfur containing granules

Thiobacillus

● Causative organism of Black Plague ● “Safety pin appearance” ● Caused by Bipolar bodies

Pasteurella multocida and Yersinia pestis

CLASSES OF DYES ● Cationic/(+) charged groups that bind to (-) charged molecules ● It will stain the acidic structures.

Basic Dyes

CLASSES OF DYES methylene blue, basic fuchsin, crystal violet, safranin, malachite green

Basic Dyes

CLASSES OF DYES ● Anionic/(-) charged groups that bind to (+) charged molecules ● It will stain the basic structures

Acid Dyes

STAINING PROCEDURES ● 1 stain is used ● Stains/Visualizes the form and shape of the bacterial cell

Simple Staining (basic/simple dyes)

STAINING PROCEDURES methylene blue, basic fuchsin, crystal violet, safranin, malachite green

Simple Staining (basic/simple dyes)

STAINING PROCEDURES use of 2 or more dyes

Differential Stain

STAINING PROCEDURES Gram Staining, Acid-Fast Staining

Differential Stain

STAINING PROCEDURES Primarily to demonstrate the capsule

Indirect / Relief / Negative Staining

STAINING PROCEDURES ● Bacteria appear as light-colored bodies against a dark background ● “Halo” appearance ● Used to visualize capsulated bacteria such as Klebsiella pneumoniae

Indirect / Relief / Negative Staining

STAINING PROCEDURES India Ink

Indirect / Relief / Negative Staining

STAINING PROCEDURES ● Used for staining special structures ● Stains for specific parts of a bacterial cell

Special Stains

STAINING PROCEDURES Special stain for cell wall

Dyar Stain

STAINING PROCEDURES Special stain for Metachromatic Granules/Inclusion Bodies

Neisser, Albert

STAINING PROCEDURES Special stain for Endospores

Fulton Schaeffer, Dorner

STAINING PROCEDURES Special stain for Flagella

Gray, Leifson

STAINING PROCEDURES Special stain for DNA

Feulgen

STAINING PROCEDURES Special stain for Spirochetes

Levaditi’s

STAINING PROCEDURES ● More sensitive as compared to routine stains ● Use of fluorochromes such as acridine orange, rhodamine-auramine (Truant Method for M. tuberculosis) and fluoroscein isothiocyanate (FITC), calcofluor white

Fluorescent Dyes

● Fundamental Staining Method in Bacteriology ● Developed by Hans Christian Gram

Gram Staining

Gram staining involves the use of (4)

Primary Stain Mordant Decolorizer Secondary Stain

Developed gram staining

Hans Christian Gram

GRAM STAIN Primary Stain: Crystal Violet - V Mordant: Gram's Iodine - V Decolorizer: 95% Ethanol or Acetone Alcohol - V Secondary Stain: Safranin O or Carbol Fuchsin - V

Gram (+)

GRAM STAIN Primary Stain: Crystal Violet - V Mordant: Gram's Iodine - V Decolorizer: 95% Ethanol or Acetone Alcohol - Colorless Secondary Stain: Safranin O or Carbol Fuchsin - Red/Dark Pink

Gram (-)

Staining method for bacteria that possess mycolic acid in their cell walls (i.e. Mycobacterium tuberculosis and other species, and Nocardia)

Acid Fast Staining

Principle: Mycolic acid, once stained by the primary stain, is able to resist the decolorization of acid-alcohol rendering them as “ACID FAST”

Acid Fast Staining

AF METHODS ● Primary Stain: Carbolfuchsin ● Mordant: Heat/Steam ● Decolorizer: Acid-alcohol ● Secondary Stain: Methylene Blue/Malachite Green

Zhiel-Neelsen - Hot Method

AF METHODS ● Primary Stain: Carbolfuchsin ● Mordant: Tergitol ● Decolorizer: Acid Alcohol ● Secondary Stain: Methylene Blue/Malachite Green

Kinyoun Method - Cold Method

[1S] UNIT 1.2 Bacterial Cell Structure Flashcards

(144 cards)