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Microbiology > Ch. 3 Bacteria cell structures and their functions > Flashcards

Ch. 3 Bacteria cell structures and their functions Flashcards

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Biology 101 flashcards
1
Q

How are bacteria and archaea different from eukaryotes?

A
  • the way their DNA is packaged - lack of nucleus and histones
  • the makeup of their cell wall - peptidoglycan and other unique chemicals
  • their internal structure - lack of membrane-bound organelles
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2
Q

What is pleomorphism?

A

variation in the size and shape of cells of a single species due to nutritional and genetic differences

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3
Q

What are the different cocci arrangements?

A
  • singular = coccus
  • diplococci = pairs
  • Tetrads = groups of 4
  • staphylococci/ micrococci = irregular clusters
  • streptococci = chains
  • Sarcina = cubical packet of 8,16, or more
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4
Q

What are the arrangements of Bacilli?

A
  • single = bacillus
  • Diplobacilli = pair of cells w/ ends attached
  • Streptobacilli = chain of several cells
  • Palisades = cells of a chain remain partially attached by a small hinge region at the end
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5
Q

What are the spiral bacterial shapes?

A
  • Vibrio = comma-shaped rods
  • spirillum = rigid helices
  • spirochetes = flexible helices
    *almost always exist as single cells; rarely attached to another after division
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6
Q

What structures are in all bacteria cells?

A
  • cytoplasmic membrane
  • cytoplasm
  • ribosomes
  • cytoskeleton
  • one (or a few) chromosomes
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7
Q

What structures do MOST bacterial cells

A
  • cell wall
  • a surface coating called a glycocalyx
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8
Q

What structures are on SOME bacteria?

A
  • flagella, pili, fimbriae
  • an outer membrane
  • plasmids
  • inclusions
  • endospores
  • microcompartments
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9
Q

What is the cell envelope and what is it made of?

A
  • lies outside the cytoplasm
  • composed of two or 3 basic layers that each perform a distinct function but together act as a single protective unit (cell wall, cytoplasmic membrane, outer membrane in some)
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10
Q

What is the cell wall function and what is it made of?

A
  • helps determine shape of bacteria
  • provides strong structural support to keep the bacterium from bursting or collapsing because of changes in osmotic pressure
  • Gains relative rigidity from peptidoglycan
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11
Q

What are peptidoglycan’s structure and function?

A
  • compound composed of repeating framework of long glycan (sugar) chains cross-linked by short peptide (protein) fragments
  • provides strong but flexible support framework
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12
Q

Characteristics of a gram-positive cell wall

A
  • thick homogeneous sheet of peptidoglycan
  • contains techoid acid and lipotechoic acid
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13
Q

What are the functions of techoic and lipotechoic acid?

A
  • cell wall maintenance and enlargement
  • contribute to the acidic charge of cell surface
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14
Q

What are the characteristics of a gram-negative cell wall?

A
  • a single thin sheet of peptidoglycan
  • thickness gives gram-negative cells greater flexibility and sensitivity to lysis
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15
Q

What is the gram-negative outer membrane made of?

A
  • similar to most membranes, except it contains specialized polysaccharide
  • lipopolysaccharide (for signaling molecules/receptors; also endotoxin)
  • Porin proteins (special membrane channels that only allow certain chemicals to penetrate)
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16
Q

What is the structure of the cytoplasmic membrane?

A
  • lipid bilayer w/ proteins embedded
  • selectively permeable - special carrier mechanisms for passage of most molecules
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17
Q

What is the function of the cytoplasmic membrane?

A
  • regulates the transport of nutrients and wastes
  • site for energy reactions, nutrient processing, and synthesis
18
Q

What are the characteristics of a gram-negative cell envelope structure?

A
  • outer membrane is an extra barrier that allows it to be resistant to certain antimicrobial chemicals. Also makes it more difficult to inhibit or kill than gram-positive
  • alcohol-based compounds dissolve lipids damaging the cell
19
Q

What are the appendages of bacteria?

A

Flagella and axial filaments
- used for motility
Fimbriae and pili
- used as attachment points

20
Q

What is the functions of the flagellum?

A

motility

21
Q

What are the 3 parts of the flagellum?

A

filament
hook
basal body

22
Q

What is chemotaxis?

A

Movement of bacteria in response to chemical signals

23
Q

What is positive chemotaxis?

A

movement toward a favorable chemical stimulus

24
Q

What is negative chemotaxis?

A

Movement away from a repellant

25
Q

What is a run?

A

rotation of flagellum counterclockwise, resulting in a smooth linear direction

26
Q

what is a tumble?

A

Reversal of the direction of the flagellum, causing the cell to stop and change course

27
Q

What are periplasmic flagella?

A

internal flagellum enclosed in the space between the cell wall and the cytoplasmic membrane
- in spirochetes (wriggly locomotion due to the flagella)

28
Q

What are fimbriae and their function?

A
  • Small, bristle-like fibers sprouting off the surface of many bacterial cells
    -Allow tight adhesion between fimbriae and epithelial cells, allowing bacteria to colonize and infect host tissues
29
Q

What are pili and what is their function?

A
  • small projections
  • well characterized in gram-negative
30
Q

What are sex pilis function?

A
  • Type IV pilus can transfer genetic material, act like fimbriae and assist in attachment, and act like flagella and make a bacterium motile
31
Q

What is the glycocalyx and their function?

A
  • a coating of repeating polysaccharide or glycoprotein units
32
Q

Types of glycocalyx?

A
  • slime layer - loose, protects against water and nutrient loss
  • capsule - more tightly bound, denser, thicker; produces a sticky (mucoid) character to colonies on agar
33
Q

What is the function of a slime layer?

A
  • protective
  • involved in gliding motility
34
Q

What are the functions of a capsule?

A
  • protects against phagocytosis
  • protects against desiccation
  • have greater pathogenicity
35
Q

What is the cytoplasm and its function?

A
  • a complex mixture of sugars, amino acids, and salts
  • 70-80% water
  • serves as a pool for building blocks for cell synthesis or sources of energy
36
Q

Where are bacterial chromosomes held?

A
  • DNA is aggregated in the nucleoid
  • the hereditary material of most bacteria exists in the bacterial chromosome
37
Q

What are plasmids and their function?

A
  • small nonessential pieces of DNA
  • confer protective traits such as drug resistance and toxin and enzyme production
  • circular or linear, independent of chromosomes
38
Q

What is the functions of ribosomes? What is their structure?

A

Site of protein synthesis
- composed or rRNA and protein
- consist of a large and small subunit

39
Q

What are inclusion bodies and microcompartments’ functions?

A
  • used for food storage
  • pack gas into vesicles
  • store crystal of iron oxide w/ magnetic properties
40
Q

What are bacterial microcompartments made of?

A
  • outer shells made of protein, arranged geometrically
  • packed full of enzymes for biochemical pathways
41
Q

What are endospores and their functions?

A
  • Dormant bodies
  • produced by bacillus, Clostridia, and Sporosarcina
  • Vegetative cell that is metabolically active
  • produced for cell to survive extreme conditions. Endospores resist extremes of heat, drying, freezing, radiation, and chemicals that would kill vegetative cells
42
Q

What are some examples of medically significant endospore bacteria?

A
  • Bacillus anthracis: agent of anthrax
  • Clostridium tetani: cause of tetanus
  • Clostridium perfringens: cause of gas gangrene
  • Clostridium botulinum: cause of botulism
  • Clostridium difficile: “C. diff,” a serious gastrointestinal disease

Microbiology (10 decks)

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