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VMCB 121 > Lecture 5 Bacterial Morphology and Bacterial Anatomy > Flashcards

Lecture 5 Bacterial Morphology and Bacterial Anatomy Flashcards

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1
Q

small, microscopic, unicellular, prokaryotic organisms that do not have membrane-bound organelles and lack a true nucleus
derived from ancient Greek word “backerion” meaning “cane” because 1st bacteria observed were bacilli

A

bacteria

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2
Q

study of bacteria and branch of microbiology

A

bacteriology

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3
Q

Bacterial Morphology

A

A. Size
- 0.2-1.5 micrometers in diameter and 3-5 micrometers in length
B. Shape
- coccus, bacillus, or spiral
C. Arrangement
- cocci, bacilli, others

SSA

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4
Q

Bacterial Morphology
A. Size

Bacteria typically range from - micrometers in diameter and about - in length

A

0.2-1.5 mu m diameter
3-5 mu m length

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5
Q

Bacterial Morphology
A. Size

  1. Smallest bacteria (~0.2 micrometers)
A

Mycoplasma species

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6
Q

Bacterial Morphology
A. Size

  1. Longest bacteria (about 1 cm long)
A

Thiomargarita magnifica

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7
Q

Bacterial Morphology
A. Size

  1. One of the largest (~750 micrometers)
A

Epulopiscium fishelsoni

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8
Q

Bacterial Morphology
B. Shape

A

Cocus (spherical)
Bacillus (rod-shaped)
Spiral (curved or helical)

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9
Q

Bacterial Morphology
B. Shape

  1. Coccus (spherical) examples
A

Staphylococcus aureus (clusters)
Streptococcus pyrogenes (chains)

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10
Q

Bacterial Morphology
B. Shape

  1. Bacillus (rod-shaped) examples
A

Escherichia coli
Bacillus subtilis

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11
Q

Bacterial Morphology
B. Shape

  1. Spiral (curved or helical) examples
A

Treponema pallidum (syphilis)
Helicobacter pylori (stomach ulcers)

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12
Q

Bacterial Morphology
C. Arrangement

a. Cocci Arrangement

A
  1. Monococci
  2. Diplococci
  3. Streptococci
  4. Staphylococci
  5. Tetrads
  6. Sarcinae
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13
Q

Bacterial Morphology
C. Arrangement

b. Bacilli Arrangement

A
  1. Bacillus
  2. Diplobacilli
  3. Streptobacilli
  4. Palisade
  5. Coccobacilli
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14
Q

Bacterial Morphology
C. Arrangement

c. Others Arrangement

A
  1. Spiral
  2. Curved
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15
Q

Bacterial Morphology
C. Arrangement
a. Cocci Arrangement

Exist as individual cells

A
  1. Monococci (Micrococcus luteus)
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16
Q

Bacterial Morphology
C. Arrangement
a. Cocci Arrangement

Cocci arranged in pairs when cocci divide and remain together

A
  1. Diplococci (Streptococcus pneumoniae)
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17
Q

Bacterial Morphology
C. Arrangement
a. Cocci Arrangement

Long chains when cells adhere after repeated divisions in one plane

A
  1. Streptococci (Streptococcus pyogenes, Streptococcus agalactiae, Enterococcus, and Lactococcus)
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18
Q

Bacterial Morphology
C. Arrangement
a. Cocci Arrangement

Grape like clusters when cocci divide in random planes

A
  1. Staphylococci (Staphylococcus aureus, S. saprophyticus)
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19
Q

Bacterial Morphology
C. Arrangement
a. Cocci Arrangement

Square groups of 4 cells when cocci divide in 2 planes (2d)

A
  1. Tetrads (Aerococcus urinae)
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20
Q

Bacterial Morphology
C. Arrangement
a. Cocci Arrangement

Cubical packets of 8 of cells when cocci divide in 3 planes (3d cube)

A
  1. Sarcinae (Sarcina spp., Clostridium spp.)
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21
Q

Bacterial Morphology
C. Arrangement
b. Bacilli Arrangement

Single unattached rod-shaped bacteria

A
  1. Bacillus (Salmonella enterica, Bacillus cereus)
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22
Q

Bacterial Morphology
C. Arrangement
b. Bacilli Arrangement

Bacilli arranged in a pair

A
  1. Diplobacilli (Moraxella bovis, Bacillus licheniformis)
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23
Q

Bacterial Morphology
C. Arrangement
b. Bacilli Arrangement

Bacilli arranged in chains

A
  1. Streptobacilli (Streptobacillus moniliform)
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24
Q

Bacterial Morphology
C. Arrangement
b. Bacilli Arrangement

Bacilli arranged in fence-like form, resembling the letter V presenting in a cuneiform or Chinese letter arrangement

A
  1. Palisade (Corynebacterium diphtheriae)
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25
Bacterial Morphology C. Arrangement b. Bacilli Arrangement Bacilli with rounded ends or oval-shaped
5. Coccobacilli (Chlamydia spp., Haemophilus influenzae)
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Bacterial Morphology C. Arrangement c. Others Arrangement Long helical-shaped or twisted bacteria
1. Spiral (Spirilla spp., Spirochetes spp.)
27
Bacterial Morphology C. Arrangement c. Others Arrangement Comma-shaped in structure
2. Curved/Comma (Vibrio spp.)
28
Bacterial Anatomy
I. Surface Components A. Glycocalyx B. Cell wall C. Cell membrane II. Appendages A. Flagella B. Pili/Fimbriae III. Internal Components A. Cytoplasm B. Ribosomes C. Intracytoplasmic inclusions D. Bacterial nucleus E. Bacterial spores SAI SGCC, AFP/F, ICRIBB
29
Bacterial Anatomy Bacterial cell components can be divided into:
a. The outer layer or cell envelope b. Cellular appendages
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Bacterial Anatomy a. The outer layer or cell envelope consists of 2 components:
1. Cell wall 2. Cytoplasmic or plasma membrane - beneath cell wall
31
Bacterial Anatomy b. Cellular appendages - some bacteria may possess additional structures such as
Capsule Flagella Fimbriae *Glycocalyx (Capsule/Slime Layer)
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Bacterial Anatomy Surface Components The general term for any network of polysaccharide or protein containing material extending outside of the cell
A. Glycocalyx
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Bacterial Anatomy Surface Components A. Glycocalyx Two types
Capsule Slime Layer
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Bacterial Anatomy Surface Components A. Glycocalyx (Capsule/Slime layer) Thick, structured layer providing protection (e.g. Streptococcus pneumoniae evades immune defense)
Capsule
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Bacterial Anatomy Surface Components A. Glycocalyx (Capsule/Slime layer) Loosely attached, aiding in biofilm formation (Pseudomonas aeruginosa)
Slime layer
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Bacterial Anatomy Surface Components A. Glycocalyx (Capsule/Slime layer) Functions of glycocalyx
Promote attachment to surfaces Prevent phagocytosis Protect cell from adverse physcial factors, infective agents Promote stability of bacterial suspension by preventing aggregation and settling out Serve as virus receptor Depot for waste products Resistance to drying
37
Bacterial Anatomy Surface Components Layer that lies just outside the plasma (cytoplasmic) membrane Essential for maintaining shape and preventing osmotic lysis Made of peptidoglycan (murein)
B. Cell wall
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Bacterial Anatomy Surface Components B. Cell wall A polymer of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) crosslinked by peptides
Peptidoglycan (murein)
39
Bacterial Anatomy Surface Components B. Cell wall Cell wall consists of:
1. Periplasm (Peptidoglycan) 2. Outer membrane
40
Bacterial Anatomy Surface Components B. Cell wall Functions of the cell wall
1. shape and rigidity to cell 2. supports weak cytoplasmic membrane against high internal osmotic pressure of protoplasm 3. maintain characteristic shape of bacterium 4. takes part in cell division 5. functions in interactions (e.g. adhesion) with other bacteria and mammalian cells 6. provide specific protein and carbohydrate receptors for attachment of some bacterial viruses
41
Bacterial Anatomy Surface Components B. Cell wall Gram + vs Gram - Cell wall _ _ bacteria have uniformly dense cell wall consisting of peptidoglycan Cell wall (peptidoglycan) Cell membrane
Gram +
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Bacterial Anatomy Surface Components B. Cell wall Gram + vs Gram - Cell wall _ _ bacteria have very thin peptidoglycan layer and an outer membrane Outer membrane of cell envelope Periplasmic space Peptidoglycan layer Periplasmic space Cell membrane
Gram -
43
Bacterial Anatomy Surface Components B. Cell wall Gram + bacteria consists of
1. Periplasm (peptidoglycan) - 50-90% of dry weight of wall, thicker and stronger than those of gram - 2. Teichoic acid - consists primarily of an alcohol (glycerol or ribitol) and phosphate a. wall teichoic acid - covalently linked to peptidoglycan b. membrane teichoic acid (lipoteichoic acid) - covalently linked to membrane glycolipid and concentrated in mesosomes G + bacterial cell wall is about 80 nm thick, composed mostly of several layers of peptidoglycan
44
Bacterial Anatomy Surface Components B. Cell wall Gram - bacteria consists of
1. Peptidoglycan - single-unit thick, 5-10% DW of wall of gram - 2. Outer membrane - bilayered structure external to peptidoglycan 3. Lipoprotein - attach cov and noncov to peptidoglycan by their protein portion and to outer membrane by lipid component 4. Lipopolysaccharide (LPS) - unique to gram - outer membrane - lipid A, core polysacc, O antigen
45
Bacterial Anatomy Surface Components B. Cell wall Cell wall peptidoglycan synthesis Composed of a overlapping lattice of 2 sugars that are crosslinked by amino acid bridges. Two sugars are:
1. N-acetyl glucosamine (NAG) 2. N-acetyl muramic acid (NAM) - only found in cell walls of bacteria - attached to NAM: side chain generally of 4 amino acids L-alanine, D-alanine, D-glutamic acid, Diamino pimelic acid (PMA)
46
Bacterial Anatomy Surface Components B. Cell wall Steps in Cell Wall Synthesis
1. Cytoplasmic Phase (Precursor Synthesis) a. Formation of UDP-NAM and UDP-NAG b. Addition of peptide side chains 2. Membrane Phase (Lipid Carrier Transport) a. Bactoprenol (Undecaprenyl Phosphate) acts as a transporter b. Peptidoglycan precursors transporters across the membrane 3. Extracellular Phase (Cross-Linking) a. Polymerization of NAM-NAG chains b. Transpeptidaation (cross-linking of peptides) catalyzed by Penicillin-Binding Proteins (PBPs) CWS CME
47
Bacterial Anatomy Surface Components B. Cell wall Enzymes that are major targets for antibiotic development
1. Mur Enzymes (MurA, MurB, MurC) - catalyze precursor synthesis 2. Transglycosylases - link sugar chains (NAG-NAM polymers) 3. Transpeptidases (PBPs) - form peptide cross-links
48
Bacterial Anatomy Surface Components Thin (5-10 nm thick) Composed of phospholipids and proteins The major barrier in the cell, separating inside of cell from outside Phospholipid bilayer Head is _ (water loving) Tails that face interior of cell membrane are _ (water fearing)
C. Cell membrane Hydrophilic head, hydrophobic head
49
Bacterial Anatomy Surface Components C. Cell membrane Functions of the cell membrane
1. Semipermeable membrane - controlling inflow and outflow of metabolites to and from protoplasm 2. Housing enzymes - outer membrane synthesis, cell wall synthesis, assembly and secretion of extra cytoplasmic and extracellular substances 3. Housing sensory and chemotaxis proteins that monitor chemical and physical changes in envi 4. Generation of chemical energy (e.g. ATP) 5. Cell motility 6. Mediation of chromosomal segregation during replication
50
Bacterial Anatomy Cellular Appendages Slender threadlike portion, long, hollow, helical filaments (3-20 mu m long) Originates in bacterial protoplasm, extruded through cell wall Made of flagellin protein Typically 5-10 per bacterial cell Powered by proton motive force (H+ gradient)
A. Flagella
51
Bacterial Anatomy Cellular Appendages A. Flagella Structures
1. Filament - longest and most obvious portion 2. Hook - short, curved segment which links filament to basal body 3. Basal body - embedded in cell (cytoplasmic membrane) In gram - bacteria, basal body has 4 rings connected to a central rod (L, P, S, M)
52
Bacterial Anatomy Cellular Appendages A. Flagella Flagellar Synthesis
If a flagellum is cut off it will regenerate until it reaches a MAX LENGTH Growth is not from base but from TIP The filament is HOLLOW, subunits travel through filament and self-assemble at the end During assembly, protein components are added at flagellar TIP rather than at base
53
Bacterial Anatomy Cellular Appendages A. Flagella Arrangements
1. Monotrichous - single polar flagellum (Vibrio cholerae) 2. Amphitrichous - single flagellum at both ends (Alcaligenes faecalis) 3. Lophotrichous - tuft of flagella at one or both ends (Spirillum) 4. Peritrichous - flagella surrounding cell -trichus - haair -lopho - tuft -amphi - both sides -peri - around
54
Bacterial Anatomy Cellular Appendages Short, fine, hairlike surface appendages (0.1-1.5 mu m in length and uniform width 4-8 nm) Shorter and thinner than flagella Single cells have been seen to be covered with 10-1000 fimbriae Originate in cytoplasmic membrane, composed of structural protein subunits termed pilins Occur in nonmotile and motile strains
B. Pili or Fimbriae
55
Bacterial Anatomy Cellular Appendages B. Pili or Fimbriae Functions of pili or fimbriae
Do not function in motility Thought to be important in attachment to surfaces or cells sticking together
56
Bacterial Anatomy Cellular Appendages B. Pili or Fimbriae Two types of pili
1. Ordinary (common) pili - organs of adhesions that allow attachment of bacterial cell to other cells or surfaces - adhesive property may be of value to bacteria in holding them in nutritionally favorable microenvironments 2. Sex pili - about 1-10 per cell similar to fimbriae but functionally different - longer and fewer in number than fimbriae - genetically determined by sex factors or conjugative plasmids, involved in transfer of DNA during conjugation
57
Bacterial Anatomy Internal Components A viscous watery solution or soft gel cell material bounded by cytoplasmic membrane Composed of 3 areas: _, _, _
A. Cytoplasm Composed of 3 areas: a. cytoplasmic area - granular b. chromatinic area c. fluid portion - contain inclusion and vacuoles
58
Bacterial Anatomy Internal Components Small, electron-dense particles in cytoplasmic region Location for all bacterial protein syntheis Main function: read RNA and synthesize PROTEINS
B. Ribosomes
59
Bacterial Anatomy Internal Components B. Ribosomes Types of RNA
mRNA - encodes proteins tRNA - adaptor between mRNA and amino acids rRNA - forms ribosome
60
Bacterial Anatomy Internal Components Not permanent or essential structures and may be absent under certain conditions of growth These bodies are usually for storage and reduce osmotic pressure by tying up molecules in particulate form Consist of volutin (polyphosphate), lipid, gllycogen, starch or sulfur
C. Intracytoplasmic Inclusions
61
Bacterial Anatomy Internal Components Single circular DNA chromosome (no nucleus) Supercoiled DNA allows it to fit inside small bacterial cell Irregularly shaped region in bacterial cytoplasm where circular DNA chromosome is located Lacks a surrounding membrane Contains: - single, circular double-stranded DNA molecule - proteins that help in DNA folding and regulation
D. Nucleoid
62
Bacterial Anatomy Internal Components Small, circular DNA molecules that - carry extra genes (antibiotic resistance genes) - can be transferred between bacteria through conjugation - used in biotechnology (genetic engineering, cloning)
E. Plasmids
63
Bacterial Anatomy Internal Components name _ is suggestive of a spore or seed-like form (endo means within) 2-phase life cycle: _, _
F. Endospore 2 phase life cycle: 1. Vegetative cell - metabolically active 2. Endospore - when exposed to adverse envi conditions, capable of high resistance and very long term survival
64
Bacterial Anatomy Internal Components F. Endospores Can remain dormant indefinitely (not reproductive) but germinate quickly when appropriate trigger is applied
Metabolically inactive Stable for years Endospores differ significantly from vegetative or normally functioning cells Formed by gram + bacteria Bacteria | Disease Bacillus anthracis - anthrax Clostridium botulinum - botulism Clostridium perfringens - gas gangrene Clostridium tetani - tetanus
65
Bacterial Anatomy Internal Components F. Endospores Properties of Endospores
1. Core - spore protoplast containing normal cell structures but is metabolically inactive 2. Spore wall - innermost layer surrounding inner spore membrane, conntains normal peptidoglycan and becomes cell wall of germinating vegetative cell 3. Cortex - thickest layer of spore envelope, cortex peptidoglycan is extremely sensitive to lysozyme and autolysis plays a role in spore germination 4. Spore coat - cortex is enclosed by fairly thick spore coat 5. Exosporium - some have additional rather loose covering which may have distinctive ridges and grooves Spore - can survive adverse conditions for years - Core - DNA, ribosomes, glycolytic enzymes - Cytoplasmic Membrane - Spore wall - normal peptidoglycan - Cortex - thick layer of cross-linked peptidoglycan - Keratin Spore Coat - protein CCSCK
66
Bacterial Anatomy Internal Components E. Endospores Shape and Position of Bacterial Spore
2 shapes: oval or spherical 3 positions: central, subterminal, terminal 2 bulges: bulging or nonbulging FREE SPORE Oval central nbg (oval middle) Spherical central nbg (circle middle) Oval subterminal nbg (oval near end) Oval subterminal bg (oval near end bulged) Oval terminal bg (oval end bulged) Spherical terminal (circle end bulged) FREE SPORE
67
Bacterial Anatomy Internal Components F. Endospores Sporulation
1. DNA is copied 2. Spore septum forms 3. Peptidoglycan layers develop 4. Spore coat provides protection 5. Endospore is released and remains dormant until conditions improve Germination - return to vegetative growth
68
Bacterial Anatomy Internal Components F. Endospores
Dehydrated, metabolically inactive Thick coat Resistant to ordinary cleaning methods and boiling Pressurized steam at 120 degrees C for 20-30 minutes will destroy spores

VMCB 121 (17 decks)

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