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Bio251 > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

How are bacteria and archaea different from eukaryotes?

A
  1. The way their DNA is packaged: lack a nucleus and histones
  2. The makeup of their cell wall: peptidoglycan and other unique chemicals
  3. Their internal structures: lack of membrane-bound organelles
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2
Q

All bacterial cells possess…

A

Cytoplasmic membrane, cytoplasm, ribosomes, cytoskeleton, one (or a few) chromosome(s)

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3
Q

Most bacterial cells possess…

A

Cell wall and glycocalyx

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4
Q

Some, but not all bacterial cells possess…

A

Flagella, pili, fimbriae, outer membrane, nanowires/nanotubes, plasmids, inclusions, endospores, microcompartments

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5
Q

What is the cell (cytoplasmic) membrane?

A

A thin sheet of lipid and protein that surrounds the cytoplasm and controls the flow of materials into and out of the cell pool

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6
Q

What is the bacterial chromosome or nucleoid?

A

Composed of condensed DNA molecules that direct all genetics and heredity of the cell and codes for all proteins

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7
Q

What are ribosomes?

A

Tiny particles composed of protein and RNA that are the sites of protein synthesis

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8
Q

What is the cytoplasm?

A

Water-based solution filling the entire cell

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9
Q

What is the S layer?

A

Monolayer of protein used for protection and/or attachment

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10
Q

What are fimbriae?

A

Fine, hairlike bristles extending from the cell surface that help in adhesion to other cells and surfaces

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11
Q

What is the outer membrane?

A

Extra membrane similar to cytoplasmic membrane but also containing lipopolysaccharide, controls flow of materials, and portions of it are toxic to mammals when released

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12
Q

What is the cell wall?

A

A semirigid casing that provides structural support and shape for the cell

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13
Q

What is the cytoskeleton?

A

Long fibers of proteins that encircle the cell just inside the cytoplasmic membrane and contribute to the shape of the cell

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14
Q

What is a pilus?

A

An appendage used for drawing another bacterium close in order to transfer DNA to it

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15
Q

What is a glycocalyx?

A

A coating or layer of molecules external to the cell wall that serves protective, adhesive, and receptor functions, and may fit tightly (capsule) or be very loose and diffuse (slime layer)

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16
Q

What is an inclusion/granule?

A

Stored nutrients such as fat, phosphate, or glycogen deposited in dense crystals or particles that can be tapped into when needed

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17
Q

What are bacterial microcompartments?

A

Protein-coated packets used to localize enzymes and other proteins in the cytoplasm

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18
Q

What is a plasmid?

A

Double-stranded DNA circle containing extra genes

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19
Q

What is a flagellum?

A

Specialized appendage attached to the cell by a basal body that holds a long, rotating filament, the movement pushes the cell forward and provides motility

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20
Q

What are nanotubes/nanowires?

A

Membrane extensions that allow bacteria to transmit electrons or nutrients to other bacteria or onto environmental surfaces

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21
Q

What is an endospore?

A

Dormant body formed within some bacteria that allows for their survival in adverse conditions

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22
Q

In what ways can bacteria function?

A
  1. Independently as a single cell
  2. As a group in colonies or biofilms
  3. Communication through nanotubes
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23
Q

What is the average size of a bacterial cell?

A

1 um (micron)

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24
Q

What is the average circumference of a cocci?

A

1 um (micron)

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25
What is the average length and width of rods?
2 um (micron) length and 1 um (micron) width
26
What is pleomorphism?
Variations in cell wall structure caused by slight genetic or nutritional differences
27
What is a coccus?
Spherical and ball-shaped cell
28
What are some variations of cocci?
Oval, bean-shaped, pointed
29
What is a rod/bacillus?
Cylindrical cell
30
What are some variations of rods/bacilli?
Blocky, spindle-shaped, round-ended, long and threadlike (filamentous), club-shaped, drum-stick shaped
31
What is a coccobacillus?
Short and plump rod
32
What are vibrio?
Singly occurring rods that are gently curved
33
What is a spirillum?
Slightly curled or spiral-shaped body that can present as a rigid helix, twisted twice or more along its axis (like a corkscrew)
34
What are the 6 ways in which cocci can be arranged?
1. Single 2. Diplococci: pairs 3. Tetrads: groups of four 4. Staphylococci or micrococci: irregular clusters 5. Streptococci: chains 6. Sarcina: cubical packet of eight, sixteen, or more cells
35
What are the 4 ways in which bacilli can be arranged?
1. Single 2. Diplobacilli: pair of cells with ends attached 3. Streptobacilli: chain of several cells 4. Palisades: cells of a chain remain partially attached by a small hinge region at the ends (Corynebacterium species)
36
What 2 functions do appendages serve and their respective examples?
1. Motility: flagella and axial filaments 2. Attachment points or channels: fimbriae, pili, and nanotubes/nanowires
37
What is the primary function of flagella?
Motility
38
What are the 3 distinct parts of the flagellum?
1. Filament 2. Hook (sheath) 3. Basal body
39
What is polar arrangement of flagella?
Attached at one or both ends of the cell
40
What does it mean if a bacteria is monotrichous?
Has a single flagellum
41
What does it mean if a bacteria is lophotrichous?
Has small bunches or tufts of flagella emerging from the same site
42
What does it mean if a bacteria is amphitrichous?
Has flagella at both poles of the cell
43
What does it mean if a bacteria is peritrichous?
Has flagella dispersed randomly over the surface of the cell
44
What is chemotaxis?
Movement of bacteria in response to chemical signals
45
What is positive chemotaxis?
Movement toward a favorable chemical stimulus (often a nutrient)
46
What is negative chemotaxis?
Movement away from a repellant
47
What is a 'run'?
Rotation of flagellum counterclockwise, resulting in a smooth linear direction
48
What is a 'tumble'?
Reversal of the direction of the flagellum, causing the cell to stop and change course
49
What are spirochetes?
Corkscrew-shaped bacteria
50
What makes spirochete motility unique?
They possess an unusual twisting mode of locomotion caused by two or more long, coiled threads called periplasmic flagella or axial filaments
51
Where are periplasmic flagella/axial filaments?
Internal flagella enclosed in the space between the cell wall and the cytoplasmic membrane
52
What does the slime layer protect the bacterial cell from?
Water and nutrient loss
53
What gives a colony a mucoid characteristic?
Capsule
54
What does a capsule protect the bacterial cell from?
White blood cells known as phagocytes
55
What protects bacteria from becoming dislodged?
Formation of biofilms
56
Where may you find biofilms?
Teeth, plastic catheters, IUDs, metal pacemakers, other implanted medical devices
57
What 3 layers are in the cell envelope?
1. Outer membrane 2. Cell wall 3. Cytoplasmic membrane
57
Where is the cell envelope found?
Outside the cytoplasm
58
What are the 3 steps of biofilm formation?
1. Cells stick to coating on a surface 2. Cells divide and stick together by sticky extracellular deposits 3. Additional microbes are attracted to the developing mature community that has complex functions
59
In what cells is the outer membrane found in?
Gram-negative cells
60
What does the cell wall protect the bacterium from?
Bursting or collapsing due to changes in osmotic pressure
61
What is a common target of antibiotics?
Cell wall
62
How can the cell wall be affected by drugs that target it?
Disruption of its integrity and cell lysis
63
Where does most of the cell wall strength come from?
Peptidoglycan
64
What is peptidoglycan?
Repeating mesh-like network of long glycan (sugar) chains cross-linked by short peptide (protein) fragments
65
What are the 2 acids found in Gram-positive cells?
Teichoic acid and lipoteichoic acid
66
What are the properties of teichoic and lipoteichoic acids?
Cell wall maintenance and enlargement, and contribute to the acidic charge on the cell surface
67
Why may Gram-negative cells be more susceptible to cell lysis?
Thin cell wall
68
What does the polysaccharide components of lipopolysaccharide act as?
Signaling molecules
69
What are the lipid components of lipopolysaccharides?
Endotoxins that cause fever and shock
70
What is the primary stain in the Gram stain?
Crystal violet
71
What is the mordant in the Gram stain?
Gram's iodine
72
What is the decolorizer in the Gram stain?
Alcohol
73
What is the counterstain in the Gram stain
Safranin
74
What does the mordant in the Gram stain allow?
The crystal violet to form large complexes in the peptidoglycan meshwork and remain trapped to allow the Gram-positive cell to retain the purple color
75
What acid is found in Mycobacteria and Nocardia?
Mycolic acid
76
What is mycolic acid?
A very-long-chain fatty acid found in the cell walls of acid-fast bacteria that contributes to its pathogenicity and resistance to certain chemicals and dyes
77
What do the cell walls of archaea lack?
Peptidoglycan
78
What organisms naturally lack a cell wall?
Mycoplasmas
79
What disease does Mycoplasma pneumoniae cause?
Walking pneumonia
80
What stabilizes the cell membrane of Mycoplasmas against cell lysis?
Sterols
81
What is characteristic about L-forms?
Bacteria that naturally have a cell wall but lost it during part of their life cycle, role in persistent infections, and resistance to antibiotics
82
What 2 important structures are found in the outer membrane?
Lipopolysaccharide and porin proteins
83
What are porin proteins?
Special membrane channels that only the outer membrane allows certain chemicals to penetrate
84
Lipid bilayer (cytoplasmic membrane) with proteins embedded serves as a site for...
Energy reactions, nutrient processing, and synthesis
85
What does the cytoplasmic membrane?
Transport of nutrients and wastes by selective permeability
86
What does it mean for a cytoplasmic membrane to be selectively permeable?
Has special carrier mechanisms for the passage of most molecules
87
What characteristics does the outer membrane confer to Gram-negative pathogenicity?
Resistance to antimicrobials and difficulty to inhibit or kill, compared to Gram-positive bacteria
88
What do alcohol-based compounds do to the outer membrane?
Dissolve the lipids and thus damaging the cell, making alcohol swabs an effective disinfectant before medical procedures
89
What does treatment of Gram-negative bacterial infections require of drugs?
Their ability to cross the outer membrane
90
What is the cytoplasm composed of?
70-80% water, sugars, amino acids, and salts
91
What 2 forms of genetic material do bacteria possess?
1. Circular chromosome 2. Plasmids
92
Rather than a nucleus, DNA in bacteria is aggregated in the...
Nucleoid
93
What are plasmids?
Nonessential, often circular, small pieces of DNA that confer traits such as drug resistance and toxin and enzyme production
94
What are the 2 subunits that make up the bacterial ribosome?
1. Large: 50S 2. Small: 30S
95
The large and small subunit together form the ___S ribosome in bacteria
70
96
What are the functions of inclusions?
Food storage, storing gas in vesicles for buoyancy, and storing crystals of iron oxide with magnetic properties
97
What are microcompartments?
Has outer shells made of geometrically arranged protein and contain enzymes used for biochemical pathways
98
How is the cytoskeleton arranged?
Helical ribbons of protein arranged around the cell
99
What is the primary function of the cytoskeleton?
Contribute to cell shape
100
Why may the bacterial cytoskeleton be a potential antibiotic target?
Its chemical structure is different than the eukaryotic cytoskeleton
101
What are endospores?
Dormant bodies produced by sporulation as a result of poor environmental conditions for the cells
102
What are endospores resistant to?
Heat, drying, freezing, radiation, and chemicals, which would kill vegetative cells
103
What is considered a vegetative cell?
Metabolically active cell
104
What genera are endospores produced by?
Bacillus, Clostridium, Sporosarcina
105
What organism is the cause of anthrax?
Bacillus anthracis
106
What organism is the cause of tetanus?
Clostridium tetani
107
What organism is the cause of gas gangrene?
Clostridium perfringens
108
What organism is the cause of botulism?
Clostridium botulinum
109
What organism is the cause of C. diff (serious gastrointestinal disease)?
Clostridioides difficile
110
Is archaea most closely related to bacteria or eukarya?
Eukarya
111
Extremophiles can (of archaea) be found, or metabolize...
In extremely high or low temperatures, extremely high salt or acid concentrates, and can metabolize sulfur or methane
112
What is Bergey's Manual of Systematic Bacteriology?
Comprehensive view of bacterial and archaeal relatedness based on rRNA sequencing
113
What is Bergey's Manual of Determinative Bacteriology?
Manual that categorizes organisms based on traits commonly assayed in clinical, teaching, and research labs such as microscopic shape and metabolic capabilities
114
What are the 4 major divisions of bacteria and archaea based on the nature of the cell wall?
1. Gracilicutes 2. Firmicutes 3. Tenericutes 4. Mendosicutes
115
What are gracilicutes?
Gram-negative bacteria with thin cell walls
116
What are firmicutes?
Gram-positive bacteria with thick cell walls
117
What are tenericutes?
Bacteria that lack a cell wall and are soft
118
What is a bacterial species?
Collection of bacterial cells, all of which share an overall similar pattern of traits and share at least 95% of their genome
119
What are mendosicutes?
Archaea, primitive cells with unusual cell walls and nutritional habits
120
What is a bacterial subspecies, strain, or type?
Bacteria of the same species that have differing characteristics
121
What is a serotype?
Representative of a species that stimulate a distinct pattern of antibody (serum) responses because of unique surface molecules
122

Bio251 (6 decks)

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