P1 | Bacterial Cell Components (LECTURE) Flashcards
referred to as the peptidoglycan [main component], or murein layer
CELL WALL
other components of the cell wall?
(PB,P)
- Phospholipid bilayer
- protein
This structure gives the bacterial cell shape and strength to withstand changes in environmental osmotic pressures that would otherwise result in cell lysis.
CELL WALL
Gives structure to the shape of the cell
CELL WALL
Gives strength; resists any mechanical disruption
CELL WALL
Acts as an osmotic barrier to the passage of larger substances
CELL WALL
Location of electron transport chain = ?
energy is generated
protects against mechanical disruption of the cell
CELL WALL
offers some barrier to the passage of larger substances.
CELL WALL
Differential staining method → cell wall ang target
- Gram positive: (color)
- Gram Negative: (color)
**Gram Stain Reaction
**
- Purple
- Red
4 COMPONENTS OF GRAM STAINING TECHNIQUES
(C,G.I,A,S)
- Crystal Violet
- Gram’s Iodine
- Acetone/Alcohol
- Safranin
- Crystal Violet:
- Gram’s Iodine:
- Acetone/Alcohol:
- Safranin:
- Primary stain
- Mordant [strengthen the affinity of the stain to the bacterial cell wall]
- Decolorizer [95% ethanol or ethyl alcohol]
(Gram positive – purple, Gram negative – colorless [thin peptidoglycan]) - Secondary Stain/Counterstain
Gram (+): Purple, Gram (-): Pink
Before the staining process, the bacterial cell wall is?
colorless
2 FIXATION METHOD:
- Physical [heat]
- Chemical [methyl alcohol]
gel-like substance that either contains enzymes that are degradative.
- can only be seen at the gram negative
Periplasmic Space
important for invasion; capable of degrading the host’s surface;
Degradative enzymes
_______ have greater virulence
(G.N.O)
Gram Negative organisms
Assists in the capture of nutrients from the environment
Degradative enzymes
channel for water and other molecules that open and close for the substances’ entry
porin
Has a very thick protective peptidoglycan (murein) layer
GRAM POSITIVE CELL WALL
provide rigidity to the cell wall by attracting magnesium and calcium
(T.A)
Teichoic acid
acts as regulator of autolytic wall enzyme, regulate the antigenic properties (has antigen)
(L.A)
lipoteichoic acid
Stimulate the immune response of the host
(A.P)
Antigenic properties
Autolytic wall enzyme
example:
(MC)
muramiclase (anti-microbial enzyme)
Thin peptidoglycan layer
GRAM NEGATIVE CELL WALL
GRAM NEGATIVE CELL WALL
(P,O,I)
- Periplasmic Space
- Outer membrane: proteins, phospholipids, and lipopolysaccharide (LPS)
- Inner membrane: Phospholipid bilayer, periplasmic space, murein layer
Functions of the Outer Membrane
(B,S,A)
- acts as a barrier to hydrophobic compounds and harmful substances
- It acts as a sieve, allowing water-soluble molecules to enter through protein-lined channels called porins.
- It provides attachment sites that enhance attachment to host cells.
a characteristic exhibited by gram positive bacteria
- bacteria has the capability of demonstrating both reactions
- only happens at gram positive
(GV)
GRAM VARIABILITY
Natural gram variability:
(M.SPP & GV)
- Mobiluncus spp.
- Gardnerella vaginalis
has been in the refrigerator for more than 24 hrs
Old culture
in the incubator for less than 24 hrs
Fresh culture
Concept of Staining:
(AS - BC)
(AS - AC)
- Acid stain → basic component
- Alkaline Stain → acidic component
(Gram variability)
Contributing factors
(U.P.B.S)
- Use of old culture
- pH of staining reagents
- bacterial autolysis
- Staining reaction time
Staining Reaction Time:
- Primary stain
- Mordant
- Decolorizer
- Secondary stain
- 1 minute
- 1 minute
- until colorless [2 seconds]
- 30 seconds - 1 minute [depending on the manufacturer’s instructions]
All COCCI are Gram POSITIVE except:
(N.V.M) or (N.B/M.V)
- Neisseria sp.
- Branhamella/Moraxella sp.
- Veillonella sp.
All BACILLI are Gram NEGATIVE except:
(MBCCLLEARK) or (MY BELL CRACK)
- Mycobacterium spp.
- Bacillus spp.
- Clostridium spp.
- Corynebacterium spp.
- Lactobacillus spp.
- Listeria spp.
- Erysipelothrix spp.
- Aerobic Actinomyces spp.
- Rothia spp.
- Kurthia spp.
usually have a gram-negative reaction NOT because it has a gram-negative cell wall but because they DO NOT HAVE a CELL WALL.
(M.U.A)
- Mycoplasma spp.
- Ureaplasma spp.
- Acholeplasma
spp.
are very difficult to stain using gram staining, however, stainable spirals are usually gram negative
Spirals
have a gram-positive cell wall structure, however, because 60% of the cell wall is made of hydrophobic lipids mainly mycolic acid, it affects its permeability this makes it difficult to gram stain.
(M&N SPP)
Mycobacterium & Nocardia spp.
contain a waxy layer of glycolipids and fatty acids (mycolic acid)
(AFCW)
ACID FAST CELL WALL
specifically designed for a subset of bacteria whose cell walls contain long-chain fatty (mycolic) acids.
ACID FAST STAINING
Differential staining method:
- Acid fast: (color)
- non-acid fast: (color)
[no mycolic acid – nonacid fast]
- pink/red
- blue green
render the cells resistant to decolorization, even with acid alcohol decolorizers.
(M.A)
Mycolic acids
are the most commonly encountered acid-fast bacteria, typified by Mycobacterium tuberculosis, the etiologic agent of tuberculosis
Mycobacteria
Partially Acid-Fast Organism:
(N.R.LM)
- Nocardia
- Rhodococcus
- Legionella micdadei
Distinctly Acid Fast:
(C.I)
- Cryptosporidium
- Isospora
2 methods of acid-fast staining:
- Ziehl-Neelsen Method (hot method)
- Kinyoun Method (cold method)
Ziehl-Neelsen Method (hot method) components:
(P.M.D.C)
- Primary Stain – Carbol Fuchsin
- Mordant – Heat
- Decolorizer – Acid Alcohol [3% HCl in 95% ethanol]
- Counterstain – Methylene Blue or Malachite Green
HCl - Hydrochloric acid
does not require the use of heat or boiling water, minimizing safety concerns during the procedure.
- referred to as the “Cold” method
KINYOUN METHOD
Kinyoun Method (cold method) components
(P.M.D.C)
- Primary Stain – Carbol Fuchsin
- Mordant – Tergitol [chemical fixation]
- Decolorizer – Acid Alcohol [3% HCl in 95% ethanol]
- Counterstain – Methylene Blue or Malachite Green
Report Gram Stain:
(C,R,M,A)
- Combine reaction, morphology, and arrangement
- Reaction: Gram-positive or Gram-negative
- Morphology: Cocci, Bacilli, Diplococci, etc.
- Arrangement: Singly, pair, cluster, tetrad, in chain
National Tuberculosis Association Method:
- 1-2 per slide: # and request another sample
- 3-9 per slide: Rare (1+)
- 10 or more per slide: Few (2+)
- 1 or more per field [OIO]: Numerous (3+)
a phospholipid bilayer embedded with proteins that envelops the cytoplasm, but does not contain sterols except:
(CP/PM)
(MP/UP)
CYTOPLASMIC/PLASMA MEMBRANE
- Mycoplasma/Ureaplasma
present in both gram-positive and gram-negative bacteria
Cytoplasmic/Plasma Membrane
Is the deepest layer of the cell envelope.
Cytoplasmic/Plasma Membrane
Serves as an additional osmotic barrier and is functionally similar to the membranes of several of eukaryotic cellular organelles.
Cytoplasmic/Plasma Membrane
folds or invagination along the length of the cytoplasmic/plasma membrane which serves as a point of attachment for chromosomes
- where nucleoid region is attached
MESOSOMES
sites of protein synthesis in bacterial cells which has a size of 70S comprised of two subunits being 50S and 30S.
- meaning of “S”?
(FR)
FREE RIBOSOMES
- Svedburg unit [describe the size of a genome]
serves as depot or storage deposits sites under certain circumstances such as limited or excess of a particular nutrient.
(IB)
INCLUSION BODIES
may accumulate, precipitate out, and form an inclusion body which is not bounded by a membrane freely floating in the cytoplasm of the bacterial cell.
(IB)
INCLUSION BODIES
may be in the form of glycogen (carbohydrate reserves, polyphosphates (ATP reserves), and poly-β hydroxybutyricacid (lipid reserves)
INCLUSION BODIES
contains lipids (Mycobacterium tuberculosis)
(MG)
MUCH GRANULES
contains polyphosphates or inorganic phosphates (Corynebacterium diphtheriae)
(V/B-EB/MG)
VOLUTIN/BABES-ERNST BODIES/ METACHROMATIC GRANULES
prominent staining of each end of the bacilli Yersinia pestis using Methylene Blue or WAYSON stain giving it a “safety pin appearance”
(BB)
BIPOLAR BODIES
BIPOLR GRANULES:
(B.SPP)
Bordetella spp.
- VIRULENCE FACTOR
- complex multilayered highly refractile structure that can be found within the cytoplasm of the vegetative cell of the bacteria or in the environment when the bacterial cell has been disintegrated.
(BS/E)
BACTERIAL SPORES/ENDOSPORES
serves as a resting or hibernating stage for bacteria when they are exposed to unfavorable conditions.
(BS/E)
BACTERIAL SPORES/ENDOSPORES
It is highly resistant to desiccation, heat, chemical agents.
(BS/E)
BACTERIAL SPORES/ENDOSPORES
MAIN COMPOSITION (bacterial spores/endospores):
(CD)
(C-DAC)
- Calcium Dipicolinate
- Calcium-Dipicolinic Acid Complex
Spore-Forming Bacteria/Sporulating Bacteria:
(B.SPP)
(C.SPP)
- Bacillus spp.
- Clostridium spp.
Protein projections that are thinner and shorter than flagella and are most usually found in gram negative bacteria.
(P)
PILI (PLURAL) OR PILUS (SINGULAR)
- Latin, fringe
- Latin, hairs
- FIMBRIAE
- PILI
The terms FIMBRIAE (Latin, fringe) and PILI (Latin, hairs) are commonly used synonymously according to?
(B, 1965)
(D & A, 1967)
- Brinton, 1965
- Duguid & Anderson, 1967
(pili or pilus)
COMPOSITION: made up of protein material known as___?
PILIN
usually shorter, numerous, sticky hair-like appendages that are primarily used for adherence to one another, host cells, and environment surfaces;
- attachment
(C/S/OP)
COMMON/SOMATIC/ORDINARY PILI
usually longer and singular, long and hollow protein tubes that is primarily used for bacterial conjugation;
- DNA exchange
(S/F/FP)
SEX/FERTILITY/F PILUS
exterior protein filaments or whip-like projections which is embedded in the cell envelope with a motor attached in a basal body responsible for its propeller-like rotation of the flagella which makes bacteria move.
FLAGELLA (PLURAL) OR FLAGELLUM (SINGULAR)
flagellated bacteria are said to be?
(M.O.M)
“moving of motile”
(Flagella or Flagellum)
Composition: made up of protein material known as?
Flagellin
Associated with H Antigen (Hauch Antigen) which is very useful is serologically typing and identifying species of ____
(F & S)
- FLAGELLA (PLURAL) OR FLAGELLUM (SINGULAR)
- Salmonella
- Peritrichous:
- Lophotrichous:
- Amphitrichous:
- Monotrichous:
(A,M,S,S)
- all around the bacterium
- multiple to one end
- single to both ends
- single to one end
exterior high molecular weight appendage or structure usually made up of polysaccharide polymers or sometime polypeptides which are produced be certain bacteria depending on environmental and growth conditions surrounding the bacterial cell.
(GC)
GLYCOCALYX
2 FORMS OF GLYCOCALYX
(C & SL)
- Capsule
- Slime layer
uniform and condensed organized material that is firmly attached to the cell wall of the bacteria.
Capsule
It is associated with K Antigen (KAPSULE Antigen) and a slight change in the capsular
Capsule
Medically important capsulated bacteria:
(NM,HISB,SP,KP,BA)
- Neisseria meningitidis
- Haemophilus influenzae serotype b
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Bacillus anthracis
loose or diffused, thick, viscous unorganized material that appears to be detached from the bacterial or not firmly attached to the cell wall of the bacteria.
Slime layer
Function: primarily it also serves as a form of protection from phagocytosis, or in some instances, it helps the bacteria to adhere to host tissues or synthetic implants such as prosthetic heart valves.
(SL)
Slime layer
