Unit 2 - The Cell Episode 2 Flashcards
Some components responsible for pathogenicity
Cell Wall
M-protein
Streptococcus pyogenes
Mycolic Acid
Mycobacterium tuberculosis
M. tuberculosis are acid fast because of this
Mycolic Acid
a physical property that gives a bacterium the ability to resist decolorization by acids during staining procedures
ACID FAST
cell wall contains N-glycolylmuramic acid instead of N-acetylmuramic acid
has a very HIGH LIPID CONTENT, which creates hydrophobic permeability barrier
Mycobacterium spp.
composed of a very thick protective peptidoglycan (murein layer)
consists of glycan (polysaccharide) chains of alternating N-acetyl-d-glucosamine (NAG) and N-acetyl-d-muramic acid (NAM)
Gram-Positive Cell Wall
act by preventing synthesis of peptidoglycan
penicillin
accounts to 50% of the dry weight of the wall and 10% of the dry weight of the total cell
TEICHOIC ACID and TEICHURONIC ACID
anchored to the peptidoglycan (N-acetylmuramic acid)
glycerol or ribitol phosphate polymers combined with various sugars, amino acids, and amino sugars
TEICHOIC ACID
TYPES OF TEICHOIC ACID
Wall Teichoic Acid
Membrane Teichoic Acid
covalently linked peptidoglycan
Wall Teichoic Acid
Linked to membrane glycolipid (lipid associated), thus can also be called lipoteichoic acid
Membrane Teichoic Acid
type of teichoic acid
anchored to the Plasma Membrane
linked to the next underlying layer, plasma membrane or cellular membrane
Lipoteichoic Acid
Teichoic acid bears the antigenic determinant: Forssman antigen
Streptococcus pneumoniae
Lipoteichoic acid (LTA) is associated with M-protein
Streptococcus pyogenes
facilitates attachment of S. pyogenes to target cell (more likely sa host cell or target cell, depende sa gusto niyang lapitan)
M-protein + Lipoteichoic Acid
similar polymers, but repeat units include sugar acids (e.g., N-acetylmannosuronic or D-glucosuronic acid) instead of phosphoric acids
synthesized in place of teichoic acids when
phosphate is limiting
Teichuronic Acid
Hydrolysis of gram-positive cell wall has yielded neutral sugars
Polysaccharides
subunits of polysaccharides in the cell wall of gram-positive cell wall)
mannose, arabinose, glucosamine, and acidic sugar
composed of two layers:
- INNER PEPTIDOGLYCAN LAYER
- OUTER MEMBRANE
Gram-Negative Cell Wall
much thinner than in gram-positive cell walls
Inner Peptidoglycan Layer
bilayered
outside the peptidoglycan layer is an additional outer membrane
contains proteins, phospholipids, and
lipopolysaccharide (LPS)
Outer Membrane
are part of the nuclear envelope of gram-negative bacteria
cell wall and outer membrane
Three regions of Lipopolysaccharide (LPS):
- Antigenic-O Specific Polysaccharide
- Core Polysaccharide
- Inner Lipid A
also called Antigenic-O or O-Specific polysaccharide
useful in distinguishing species of gram negative
Antigenic-O Specific Polysaccharide
H7 E. coli (identifies specific strain or species of gram-negative bacteria)
O157
ketodeoxyoctanoic acid (KDO) and heptose
Core Polysaccharide
lipid portion of LPS
also called Endotoxin
responsible for producing fever and shock conditions in patients infected with gram negative bacteria
Inner Lipid A
when gram-negative bacteria dies, they release Lipid A, called
Endotoxins
unique to Lipid A
Beta-hydroxymyristic Acid
LPS FUNCTIONS:
- Vital in evading the host defenses
- Contribute to the negative charge of the bacterial surface, which stabilizes the membrane structure
- Considered as an endotoxin
CLINICAL USE OF CELL WALL:
Gram-Staining
GRAM POSITIVE BACTERIA
Micrococcus
Staphylococcus
Streptococcus
Peptococcus
Peptostreptoococcus
Sarcina
Bacillus
Corynebacterium
Erysipelothrix
Listeria
Mycobacterium
Nocardia
Actinomyces
Clostridium
Propionobacterium
GRAM-NEGATIVE BACTERIA
Branhamella
Neisseria
Veillonella
Acinetobacter
Aeromonas
Alcaligenes
Bordetella
Brucella
Enterobacteriaceae
Francisella
Legionella
Pasteurella
Pseudomaonas
Vibrio
Fusobacterium
Bacteriodes
stain gram-positive, have a modified cell wall called an acid-fast cell wall
Mycobacteria
contain a waxy layer of glycolipids and fatty acids (mycolic acid) bound to the exterior of the cell wall
more than 60% of the cell wall is lipid
Acid-Fast Cell Wall
major lipid component
strong “hydrophobic” molecule that forms a lipid shell around the organisms and affects its permeability
Mycolic Acid
prevents uptake of the dye
makes Mycobacterium spp. difficult to stain with gram stain
Mycolic Acid
stain faint blue (gram-positive color)
best stained with an acid-fast
Mycobacterium and Nocardia
(Clinically Relevant Aerobic Actinomyces)
Cell Wall Containing MYCOLIC ACID
→ partially acid fast
Nocardia
Rhodococcus
Gordonia
Tsukamurella
Corynebacterium
(Clinically Relevant Aerobic Actinomyces)
Cell Wall without MYCOLIC ACID
Streptococcus
Actinomadura
Dermatophilus
Nocardiopsis
Oerskovia
lack of cell wall and contain STEROLS in their cell membranes
lack the rigidity of the cell wall
seen in various shapes microscopically
Absence of Cell Wall
example of organisms with no cell wall
Mycoplasma and Ureaplasma
typically found only in gram-negative bacteria
bounded by the internal surface of the cellular membrane encompassing the thin peptidoglycan layer
Periplasmic Space
contains the murein layer, consists of gel like matrix containing nutrient-binding proteins that assist in the capture of nutrients from the environment
Periplasmic Space
contain several enzymes involved in the degradation of macromolecules and detoxification of environmental solutes, including antibiotics that enter through the outer membrane
Periplasmic Space
Hydrolytic Enzymes
Alkaline Phosphatase
5’ nucleotidase
Detoxifying Enzymes
Beta-lactamase
Aminoglycoside
Phosphorylase
Periplasmic space is _______ in gram-positive bacteria
absent
also called plasma membrane
top layer of the outer membrane (inner lipid layer)
Cytoplasmic (Inner) Membrane
present in both gram-positive and gram-negative bacteria and is the deepest layer of the cell envelope
Cytoplasmic (Inner) Membrane
consists of phospholipid bilayer, various proteins (70%), including a number of enzymes vital to cellular metabolism
serves as an additional osmotic barrier
Absence of sterols
Cytoplasmic (Inner) Membrane
Incorporate sterols (e.g., cholesterol), into their membranes when growing in sterol-containing media
Mycoplasma and Ureaplasma
Mechanisms in Membrane Transport
Passive and Active Transport
Group Translocation
diffusion
no energy consumed
happens only when Solute is at higher concentration outside than inside the cell
Passive Transport
entry of very few nutrients through plasma membrane (Oxygen, Carbon
Dioxide and Water)
Simple Passive Transport
makes use of channel proteins (selective passive transport). Only specific molecules can penetrate
Facilitated Passive Transport
Types of Active Transport
Ion Coupled Transport
ATP Binging Cassette (ABC)
proton motive/ sodium motive forces
Ion Coupled Transport
Types of Ion Coupled Transport
Uniport
Symport
Antiport
single species (Ion Coupled Transport)
Uniport
2 similar solutes (Ion Coupled Transport)
Symport
exchange transport of 2 similar solutes in opposite directions (Ion Coupled Transport)
Antiport
ATP directly transport solutes
ATP Binding Cassette (ABC)
also known as Rectorial metabolism
coupling transport mechanism
Group Translocation
substances are chemically altered during transport (cell/ membrane becomes impermeable) → hoarding of substances
uses high energy phosphate components → Phosphoenolpyruvic Acid
Group Translocation
Cytoplasmic Structures
Ribosomes
Nucleoid
Plasmid
Inclusion Bodies
Endospores/ Asexual Spores
site of protein biosynthesis and gives the cytoplasm a granular structure
consists of RNA and proteins
70s in size and separates into two subunits, 50s and 30s each consists of ribosomal RNA
Ribosomes
attach to 30s subunit and interfere with protein synthesis
Streptomycin and Gentamycin
interfere with protein synthesis by attaching to 50s subunit
Erythromycin and Chloramphenicol
→ consists of a single, circular chromosome
→ lacks nuclear membrane and mitotic apparatus
Nucleoid
appears as diffused nucleoid or chromatin body that is attached to a mesosome (sac-like structure)
consists of a single continuous circular molecule ranging in size from 0.58 to almost 10 million base pair
Nucleoid
Exemptions because they have linear chromosomes
Borrelia burgdorferi and Streptomyces coelicolor
2 dissimilar chromosomes bacteria
Vibrio cholera and Brucella melitensis
replicate independently of chromosomal DNA
extrachromosomal, double-stranded element of DNA that is associated with virulence
Plasmid
located in the cytoplasm and serve as a site for the genes to code for antibiotic resistance and toxin production
sometimes disappears during cell division and it can make bacteria (mostly Gram-negative) pathogenic
Plasmid
it is not essential for bacterial growth so bacterial cell may or may not contain this
Plasmid
Responsible for the production of B-lactamase that provide resistance to B-lactam antibiotics
Large Plasmid
B-lactam antibiotics
penicillin and oxacillin
Resistant to tetracyclines and chloramphenicol
Small Plasmid
T/F: All Bacteria Has Plasmids
False
serve as the energy source or food reserve of the bacteria or as a reservoir of structural building blocks
composed mainly of polysaccharides, they lessen osmotic pressure
Inclusion Bodies
Examples of Inclusion Bodies
- Glycogen
- Cyanophysin granules
- Poly-B-hydroxybutyrate granules
- Carboxysomes (cyanobacteria, nitrifying bacteria, and thiobacilli)
- Gas vacuoles (cyanobacteria, halobacterium, and thiothrix)
- Polyphosphate granules (volutin and matachromatic granules)
storage form of glucose
Glycogen
→ storage from of inorganic phosphates
→ source of phosphate for nucleic acid and phospholipid synthesis
Pyrophosphate Granules
stains red with blue dye (methylene blue)
Metachromatic/ Volution/ Babes-Ernst granules (Corynebacterium diphtheriae)
Bipolar bodies
Yersinia pestis
Much Granules
Mycobacterium Tuberculosis
lipid like compound consisting of chains of B-hydroxybutyric acid units connected through ester linkages
Poly-B-hydroxybutyric Acid (PHB)
produced when the source of nitrogen, sulfur or phosphorus is limited and there is excess carbon in the medium
Poly-B-hydroxybutyric Acid (PHB)
Can be stained by Sudan dyes
Bacillus and Myxobacteria
Hydrogen sulfide and thiosulfate
Sulfur Granules
inclusion body for carbon dioxide fixation
Carboxysomes
for virulence
small, dormant structures located inside the bacterial cell
Endospores/ Asexual Spores
aid in the survival of bacteria against external conditions
produced within vegetative cell in some gram-positive bacteria
Endospores
causative agent of Q fever: has spore like structure
Coxiella burnetii (gram-neg)
composed of dipicolinic acid and calcium ions (CALCIUM DIPICOLINATE)
→ some locations could be a means of microscopically identifying bacteria
→ responsible for perpetuation, but not multiplication
ENDOSPORES
Types of Spores According to Location
Terminal Spore
Subterminal Spore
Central Spore
Terminal Spore
Clostridium tetani (tetanus)
Subterminal Spore
Clostridium botulinum (food poisoning)
Central Spore
Bacillus anthracis (anthrax)
Properties of Endospores
- Core
- Spore Wall
- Cortex
- Coat
- Exosporium
(Endospore)
spore protoplast
contains a complete nucleus (chromosome), all of the components of the protein-synthesizing apparatus, and an energy-generating system based on glycolysis
Core
(Endospore)
innermost layer surrounding the inner spore membrane
contains normal peptidoglycan and becomes the cell wall of the germinating vegetative cell
Spore Wall
(Endospore)
thickest layer of the spore envelope
contains an unusual type of peptidoglycan, with many fewer cross-links than are found in cell wall peptidoglycan
sensitive to lysozyme
Cortex
(Endospore)
composed of a keratin-like protein containing many intramolecular disulfide bonds
impermeability of this layer confers on spores their relative resistance to antibacterial chemical agents
Coat
(Endospores)
composed of proteins, lipids, and carbohydrates
consists of paracrystalline basal layer and a hairlike outer region
Exosporium
Presence of Exospore:
Bacillus anthracis
Bacillus cereus
No exospore:
Bacillus athrophaeus
