Microbiology > Ch. 4 > Flashcards

Ch. 4 Flashcards

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1
Q

What are the life-defining properties to know cold?

A
  • Heredity (DNA)
  • Reproduction
  • Growth & Development
  • Metabolism (enzymes)
  • Responsiveness (chemotaxis/phototaxis)
  • Transport across membranes

These properties are essential for defining life and distinguishing living organisms from non-living entities.

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2
Q

Why are viruses generally not considered living?

A

Viruses are non-cellular and don’t express life-defining traits on their own

This includes the inability to reproduce or carry out metabolic processes without a host.

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3
Q

What is a key difference between prokaryotes and eukaryotes?

A

Prokaryotes lack a nucleus and membrane-bound organelles

Prokaryotes include Bacteria and Archaea, and they perform most activities that eukaryotes do despite lacking complexity.

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4
Q

What types of organisms are classified as prokaryotes?

A
  • Bacteria
  • Archaea

Prokaryotes are distinguished from eukaryotes by their structural simplicity.

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5
Q

What are the types of membrane-bound organelles emphasized in the next chapter?

A
  • Nucleus
  • Endoplasmic Reticulum (ER)
  • Golgi Apparatus
  • Mitochondria

These organelles are key features of eukaryotic cells.

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6
Q

Fill in the blank: Prokaryotes carry out most activities that ______ do.

A

[eukaryotes]

Despite their simpler structure, prokaryotes are capable of complex functions.

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7
Q

What are always present in a generalized bacterial cell?

A

Cell membrane, cytoplasm, ribosomes, chromosome/nucleoid

These components are essential for all bacterial cells.

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8
Q

What structures are common in most bacterial cells?

A

Cell wall, surface coating (glycocalyx)

These are found in the majority of bacterial cells but not all.

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9
Q

What are sometimes present in bacterial cells?

A

Flagella, pili, fimbriae, capsules/slime, inclusions/granules, actin-like cytoskeleton, endospores

These structures vary among different bacterial species.

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10
Q

What are the parts of a flagellum in bacteria?

A

Filament (flagellin), curved hook, basal body

These parts enable bacterial motility.

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11
Q

How does the flagellum rotate in bacteria?

A

360° rotation

This is different from the undulation seen in eukaryotic flagella.

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12
Q

What are the arrangements of flagella in bacteria?

A

Monotrichous, lophotrichous, amphitrichous, peritrichous

These terms describe the location and number of flagella on a bacterial cell.

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13
Q

What is the logic of chemotaxis in bacteria?

A

CCW = smooth ‘run’; CW = ‘tumble’

This movement is controlled by receptors in the membrane that couple sensing to motor action.

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14
Q

What are periplasmic flagella?

A

Axial filaments between outer sheath and peptidoglycan that produce corkscrew flexing/undulation

Examples include Borrelia and Treponema.

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15
Q

What is the function of fimbriae?

A

Small bristles for adhesion/biofilm formation; mutants lacking fimbriae often lose virulence

Fimbriae are important for the attachment of bacteria to surfaces.

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16
Q

What role do pili (Type IV) play in bacteria?

A

Conjugation (DNA transfer) via sex pilus and ‘twitching’ motility

Mostly found in gram-negative bacteria such as Neisseria and Pseudomonas.

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17
Q

What is the difference between a slime layer and a capsule?

A

Slime layer: loose and easily washed off; Capsule: thicker and tightly bound

The slime layer protects from drying and aids adhesion, while the capsule is anti-phagocytic.

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18
Q

Fill in the blank: A slime layer protects bacteria from _______.

A

drying

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19
Q

What is a characteristic of a capsule?

A

Thicker, tightly bound, and forms mucoid colonies; anti-phagocytic

Pathogenic examples include S. pneumoniae, H. influenzae, and B. anthracis.

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20
Q

What are biofilms and how are they formed?

A

Biofilms are built via fimbriae, pili, or capsules and involve changes in gene expression leading to antibiotic and disinfectant resistance.

Common examples include those found on catheters, IUDs, valves, and oral plaque.

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21
Q

What is the function of the cell envelope?

A

The cell envelope serves as the outer boundary of the cell.

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22
Q

What is peptidoglycan (PG) and its role?

A

Peptidoglycan is a framework of glycan chains cross-linked by short peptides that prevents osmotic lysis and is targeted by penicillins and cephalosporins.

Lysozyme hydrolyzes glycan bonds.

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23
Q

Describe the characteristics of Gram-positive walls.

A

Gram-positive walls have thick peptidoglycan (20-80 nm), teichoic and lipoteichoic acids for wall maintenance, cell division, and tissue binding, with a small periplasmic space at the membrane junction.

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24
Q

What are the key features of Gram-negative walls?

A

Gram-negative walls consist of an outer membrane and a thin peptidoglycan layer. The outer membrane contains LPS (endotoxin lipid A) and porins that regulate entry, along with pronounced periplasmic space and paces for metabolic reactions.

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25
What are the characteristics of acid-fast cell walls?
PG plus mycolic acids → waxy, chemical resistance ## Footnote Acid-fast bacteria include Mycobacterium and Nocardia.
26
What is unique about Mycoplasma in terms of cell wall structure?
No cell wall → extreme pleomorphism ## Footnote Mycoplasma is known for its variability in shape.
27
List the functions of membranes in cells.
* Energy reactions (respiration enzymes) * Nutrient processing/synthesis * Selective transport (primary gatekeeper) * Secretion ## Footnote Some bacteria have internal membrane structures for specialized functions.
28
What are cyanobacterial thylakoids used for?
Photosynthesis ## Footnote Thylakoids are internal membrane stacks that facilitate light reactions in photosynthesis.
29
What is the composition of the cytoplasm?
Water + sugars, amino acids, salts, plus the cell's DNA, ribosomes, granules ## Footnote The cytoplasm serves as the medium for biochemical reactions within the cell.
30
What type of DNA is found in the nucleoid?
Single, circular DNA ## Footnote Plasmids, which carry accessory genes, can also be present in some bacteria.
31
What are ribosomes composed of in bacteria?
70S (30S + 50S) ## Footnote Ribosomes are targets for certain antibiotics.
32
What is the function of inclusions or granules in bacteria?
Storage ## Footnote For example, polyphosphate 'metachromatic/volutin' granules are found in Corynebacterium.
33
What role does the actin-like cytoskeleton play in bacteria?
Shape/structure in some bacteria ## Footnote It is not universal across all bacterial species.
34
What are endospores, and in which genera are they commonly found?
Stress response bodies; found in Bacillus and Clostridium ## Footnote Endospores are not reproductive structures.
35
What triggers the formation of a spore from a vegetative cell?
Nutrient depletion (especially amino acids) ## Footnote This process takes approximately 6-12 hours.
36
What components contribute to the resistance of bacterial spores?
Ca-dipicolinate, cortex & spore coat ## Footnote These components provide heat, chemical, and radiation resistance, along with metabolic dormancy.
37
What is the process of germination?
Water + specific agent → hydrolytic enzymes digest cortex → rehydration/outgrowth to vegetative cell ## Footnote This process is essential for the development of spores into active cells.
38
Which bacteria are known as spore-formers?
B. anthracis; Clostridium spp. (tetani, perfringens, botulinum) ## Footnote Spore-forming bacteria are resistant to extreme conditions.
39
What temperature and time are required for sterilization of spore-formers?
121 °C steam (20-30 min) ## Footnote This is a standard method to ensure the destruction of spores.
40
What are the common shapes of bacteria?
Cocci, rods (bacilli), vibrios, spirilla, spirochetes ## Footnote Pleomorphism is common in certain genera like Corynebacterium.
41
What are the arrangements of cocci?
Diplococci, tetrads, staphylococci (clusters), streptococci (chains), sarcina (packets of 8-64) ## Footnote Bacilli can form diplo- and strepto- arrangements as well.
42
What is the size range of bacteria?
Bacteria range ~0.2 um to >10 um; coccus ~0.5-3.0 um; bacillus ~0.2-2.0 um in width ## Footnote Understanding the size of bacteria is crucial for microscopy and identification.
43
Fill in the blank: The process of germination involves _______ and specific agents that activate hydrolytic enzymes.
[water]
44
True or False: Clostridium spp. are not considered spore-formers.
False ## Footnote Clostridium spp. are well-known spore-forming bacteria.
45
Fill in the blank: The arrangement of bacterial cells in chains is known as _______.
[streptococci]
46
What is pleomorphism in bacteria?
Common variability in shape and size among certain genera ## Footnote An example is Corynebacterium, which can display palisades and metachromatic granules.
47
What is the current trend in taxonomy according to Bergey's Manual?
It now uses genetic/phylogenetic data
48
How many phyla do bacteria and archaea span according to Bergey's Manual?
Approximately 25 phyla
49
Is the Gram reaction still useful, and if so, at what levels?
Yes, mainly at lower levels
50
What analysis is recommended to master relations in classification?
rRNA analysis
51
What type of group does firmicutes represent?
A gram-positive group
52
What characteristic do many archaea possess?
They are often extremophiles
53
What type of environments are the earliest cells likely to have been analogous to?
Hot vents and sulfur environments
54
Why are viruses not considered living things?
d. All of these are correct. ## Footnote Non-cellular; no independent metabolism or reproduction
55
Which of the following is not found in all bacterial cells?
d. actin cytoskeleton. ## Footnote Membrane, ribosomes, chromosome are universal; actin-like cytoskeleton is not
56
What are the major locomotor structures in bacteria?
a. flagella. ## Footnote Bacteria lack cilia
57
What is the function of pili in bacteria?
c. gram-negative, genetic exchange. ## Footnote Conjugation via Type IV/sex pili
58
An example of a glycocalyx is _____.
a. a capsule. ## Footnote Also slime layer
59
What is the primary function of the bacterial cell wall?
c. support. ## Footnote PG resists osmotic lysis
60
What is the component present in both gram-positive and gram-negative cell walls?
peptidoglycan ## Footnote Gram-negative walls contain outer membrane (OM) and lipopolysaccharides (LPS), while gram-positive walls contain teichoic acids.
61
What are metachromatic granules concentrated in?
Corynebacterium ## Footnote Metachromatic granules consist of polyphosphate, also known as volutin.
62
What type of prokaryotes lack cell walls?
mycoplasmas ## Footnote Mycoplasmas are unique among prokaryotes due to their lack of a rigid cell wall.
63
The LPS layer releases _______ causing _______.
endotoxins; fever ## Footnote Lipid A is the component of the LPS that acts as the endotoxin.
64
What is the primary function of bacterial endospores?
survival ## Footnote Bacterial endospores are formed under stress and serve to ensure survival, not reproduction.
65
What is the arrangement of cells in packets of eight called?
sarcina ## Footnote Sarcina refers to a specific arrangement pattern of bacteria in groups of eight.
66
Spirochete vs spirillum differs mainly by _______.
nature of motility ## Footnote Spirochetes move using axial filaments, while spirilla use external flagella.
67
Phylum with gram-positive cell walls
Firmicutes ## Footnote Classic exam cue
68
Cyanobacteria belong to
Domain Bacteria ## Footnote Photosynthetic bacteria
69
Stain distinguishing wall differences
Gram stain
70
First living cells likely resembled
an archaeon ## Footnote Early hot-vent archeal-like cells
71
Structure of flagella includes
filament, hook, basal body
72
Differences between run and tumble in flagella
run vs tumble
73
Types of flagella orientation
polar vs peritrichous
74
Fimbriae are used for
adhesion
75
Pili are used for
conjugation; gram-neg
76
Glycocalyx consists of
capsule and slime layer
77
Function of the capsule in glycocalyx
anti-phagocytic
78
Characteristic of slime layer in glycocalyx
loose, dries protection
79
What is biofilm logic?
80
Differences between gram-positive and gram-negative bacteria
thick PG + teichoic vs OM + LPS + porins + periplasm; both have PG
81
What are the characteristics of Atypical bacteria?
Mycobacterium/Nocardia contain mycolic acids; Mycoplasma have no cell wall. ## Footnote Atypical bacteria differ from typical bacteria in their cell wall structure and composition.
82
What triggers endospore formation?
AA depletion triggers endospore formation. ## Footnote AA refers to amino acids, which when depleted can lead to the formation of endospores in certain bacteria.
83
What is a key component of bacterial endospores?
Calcium dipicolinate is a key component of bacterial endospores. ## Footnote Calcium dipicolinate stabilizes the endospore structure and is essential for resistance to stress.
84
List the steps involved in the germination of endospores.
Germination steps include: *activation, *germination, *outgrowth. ## Footnote These steps are crucial for the transition from dormant endospore to active bacterial cell.
85
What are the sterilization temperatures for endospores?
Sterilization temperatures for endospores typically exceed 121°C. ## Footnote High temperatures are necessary to effectively kill endospores due to their heat-resistant properties.
86
What vocabulary describes bacterial shapes and arrangements?
Shapes and arrangements include: *diplococci, *tetrad, *staphylococci, *streptococci, *sarcina, *palisades, *pleomorphism. ## Footnote These terms help classify and identify bacteria based on their morphology.
87
What is Bergey's classification system used for?
Bergey's classification system is used for the classification of bacteria. ## Footnote It provides a systematic approach to categorizing bacteria based on various characteristics.
88
What type of bacteria does the Firmicutes phylum include?
Firmicutes include gram-positive bacteria. ## Footnote Gram-positive bacteria have thick peptidoglycan layers in their cell walls, which retain the crystal violet stain used in the Gram staining procedure.
89
Which organisms are considered the earliest cells?
The earliest cells are classified as Archaea. ## Footnote Archaea are distinct from bacteria and are known for their ability to survive in extreme environments.
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