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Microbiology > Chapter 3 > Flashcards

Chapter 3 Flashcards

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Biology 101 flashcards
1
Q

What does prokaryote mean and what are characteristic of them?

A
  • prenucleus

- contain: plasma membrane, cell wall, flagella/cilia, DNA, ribosomes, NO Organelles

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2
Q

What does eukaryote mean and what characteristics represent this group?

A
  • true nucleus
  • contain: plasma membrane, cell wall in plants, no cell wall in animals, flagella/cilia, DNA that is self contained, organelles ribosomes.
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3
Q

What are the basic shapes of prokaryotes?

A
  • bacillus (rod)
  • coccus (spherical)
  • spiral
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4
Q

Can spiral shape of prokaryotes be described in more detail? If so, what are they?

A
  • spirillum (one or more twists)
  • vibrio (curved rod) one bend, look like banana
  • spirochete (flexible, helical spirals)
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5
Q

Describe what a stella bacteria looks like.

A

star shaped and is prokaryotic

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6
Q

There are multiple ways to arrange bacteria, what are three common, simple methods?

A

pair: complete binary fission with incomplete separation

  • clusters
  • chains
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7
Q

What does the prefix diplo- describe?

A

pairing of bacteria

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8
Q

What does staphylo describe?

A

clustering of bacteria

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9
Q

What does strepto describe?

A

chains of bacteria

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10
Q

Diplo and strepto- divide in how many planes?

A

1

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11
Q

Sarcinae describes what type of division of bacteria?

A

into 8ths, with 3 planes of division

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12
Q

What is the benefit of being a smaller cell?

A

there is a larger surface area to volume ratio, due to infoldings on the PM

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13
Q

Bacterial membranes do not contain sterols. With this in mind what do they use to stabilize their membrane?

A

without the presence of sterols (cholesterol) bacterial membranes contain hopanoids

-hopanoid: sterol-like in nature

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14
Q

Where can high amounts of hopanoid be found?

and what does a hopanoid do?

A

largely found in petroleum

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15
Q

True/False

Bacteria and Eukaryotes have significantly different lipids systems and therefore plasma membranes.

A

False.

Bacteria and eukaryotes are similar and both differ from the archaea

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16
Q

What do archaeal lipids contain that eukaryotic/bacterial lipids do not?

A
  • ether bonds and not ester bonds.
  • branched molecules
  • hydrophilic section: is polysaccharide not phosphate group
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17
Q

What components in eukaryotic cytoskeletal is also seen in bacteria?

A
  • actin/microfilaments
  • intermediate filaments
  • microtubules
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18
Q

FtsZ is a bacterial cytoskeletal protein. What is its function and where can it be largely found?

A
  • forms ring during septum formation during cell division

- large diversity in bacteria and archaea

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19
Q

MreB has what function?

A
  • bacterial cytoskeletal protein found in BACILLI, not in cocci.
  • maintains shape by manipulating peptidoglycan synthesis machinery
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20
Q

CreS is a bacterial cytoskeletal protein. What does it do and where is it found?

A

helpls maintain a curve shape.

- most likely found within bacteria -vibrio

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21
Q

What is a storage inclusion?

A

-granules of organic or inorganic material that will use the stores in the future

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22
Q

What is generally stored in storage inclusions?

A
  • nutrients, metabolic product, energy, building components
  • glycogen
  • carbons
  • phosphate
  • amino acids
  • sulfur granules
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23
Q

A magnetosome can be categorized as what?

A
  • storage inclusion

- uses the earth magnetic field to properly orient aquatic bacteria

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24
Q

Where is Rubisco contained?

A

-contained in a microcompartment (carboxysome)

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25
Q

What is the function of the carboxysome?

A

-fix carbon dioxide to bacteria with the help of enzyme rubisco

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26
Q

The svedburg unit is a measure of what?

A
  • how quickly a particle will sediment in centrifuge.

- The larger the number, the longer it takes for the particle to sediment and therefore the larger the particle.

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27
Q

What are characteristic features of the nucleoid?

A
  • not membrane bound
  • contains chromosomes and associated proteins
  • 1 closed circular double-stranded DNA molecule
  • participate in folding by supercoiling DNA
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28
Q

1 circular double stranded DNA molecule is generally characteristic of what?

A

prokaryotic chromosome

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29
Q

What is a plasmid?

A

extrachromosomal DNA in bacteria, archaea and fungi

-it is classified based on mode of existence, spread, and function

30
Q

What is the function of a plasmid?

A

contains and helps transfer non-essential genes, but may help improve survival (AB resistant)

-also exist and replicate independent of chromosomes

31
Q

Describe the major difference between gram positive and gram negative bacteria.

A
  • gram positive have thick peptidoglycan (cell wall) and thin PM
  • gram negative have PM, thin peptidoglycan layer, periplasmic space, and outer membrane layer.
32
Q

What is the purpose of peptidoglycan layer?

A
  • maintains bacterium shape
  • prevents osmotic lysis (when would this occur?)
  • protect against toxins
  • contributes to pathogenicity
33
Q

How does the peptidoglycan layer contribute to pathogenicity?

A
  • this layer covers the ‘flags’ presented on the PM that Ab can use to distinguish as hostile or not.
  • covering the flag makes the bacterium somewhat invisible to the Abs
34
Q

What are the components of the peptidoglycan layer?

A

-alternating strands of NAM, NAGs and an alternating pattern of D- L- amino acids.

35
Q

What is a common cross-linkage in the peptidoglycan layer of gram negative cells?

A

cross link between D- Ala and DAP

36
Q

What is the common cross linkage of the peptidoglycan layer of gram positive cells?

A

D-Ala to L-Lys with a Gly interbridge

37
Q

Why do gram positive cells contain teichoic acid, when gram negative do not?

A

the thicker peptidoglycan layer requires extra support in order to maintain the cell envelope.

Act like rebar that extend down to the PM surface

38
Q

What are the functions of the teichoic acids?

A
  • negatively charged
  • maintain cell envelope
  • protect against environmental factors
  • can bind to host cells
39
Q

Do gram positive bacteria secrete any type of enzymes?

A

-exoenzymes that work to degrade large nutrients

40
Q

What is the outer membrane composed of ans where is it located?

A
  • lipids, lipoproteins, lipopolysaccharides

- thin layer that surrounds the peptidoglycan and PM layers of gram negative bacterium

41
Q

Why are lipopolysaccharides important to bacterium?

A
  • form negative surface charge
  • stabilize outer membrane
  • attach to surfaces or form biofilm
  • protects against O Ag
  • acts as endotoxin (lipid A)
42
Q

Is the outer membrane more or less permeable when compared to the PM?

A
  • more permeable because it contains porin proteins and multiple transporter proteins that can aid in facilitated diffusion
43
Q

Describe the difference between lysis and plamolysis.

A
  • lysis occurs in a hypotonic environment as fluid will fill the cell and cause it to burst
  • plasmalysis occurs in a hypertonic environment as water will leave the cell. resulting in the cell wall to maintain structure while the PM will shrink in size
44
Q

What breaks the bond between NAG and NAMs?

A

lysozymes, which contribute to the lysis of the cell.

45
Q

Which cell types are more susceptible to lysozymes?

A

-Gram positive lack the thin outer membrane and peptidoglycan layer will be more rapidly attacked.

46
Q

What effects does penicillin have on bacterium?

A
  • inhibition of the peptidoglycan synthesis

- -reduces the layers that lysozome must penetrate in order to lyse the cell.

47
Q

What is significant about pseudopeptidoglycan?

A
  • specific to arachaea in that it will differ in chemical structure when compared to peptidoglycan
  • is similar to eukaryotic in terms of function, mrphology, and physical structure
48
Q

Lysozomes are useful in degrading peptidoglycan becasue it has an beta-1, 4-glycosidic linkage. Are lysozomes useful against pseudopeptidoglycans?

A

-No, pseudopeptidoglycans contain Beta-1, 3-glycosidic linkages and are therefore not affected by lysozomes.

49
Q

What is contained outside the cell wall?

A
  • outermost layer of cellular envelope
  • glycocalyx: capsules, slime layer, S layers
  • biofilms that attach to solid surfaces
50
Q

What is the component of a capsule and how does it benefit the bacterium?

A
  • composed of polysaccharides

- protects against desiccation and phagocytosis

51
Q

What is a slime layer?

A
  • similar to a capsule but is more diffuse and unorganized.

- will aid in motility and not adhesion

52
Q

What is an S layer and the differences between the gram positive and gram negative attachment sites?

A
  • a self assembling layer of protein or glycoproteins.
  • gram (-) attach to the outer membrane
  • gram (+) attach to the peptidoglycan surface
53
Q

A bacterium is able to maintain its shape, adhere to surfaces, protect itself from host defense, and protects itself from environmental dangers. What is present that allows a bacterium to do so?

A
  • S layer
54
Q

Fimbriae can do what?

A
  • mediate attachment to surfaces

- - type IV used in twitching or gliding motility

55
Q

What is the purpose of a sex pili?

A

allows for the exchange of plasmids and other DNA material during conjugation with other bacterium

56
Q

What are the three parts of flagella in bacteria?

A
  • filament: extends from cell surface to tip and is a hollwo rigid cylinder
  • Hook: links the filament to the basal body
  • Basal Body: the series of rings, attached to the different membrane layers that act as the motor unit
57
Q

Monotrichous

Amphitrichous

A
  • one flagellum

- one flagellum at each end

58
Q

Polar flagellum

A

-flagellum at end of cell

59
Q

Lophotrichous

A

cluster of flagella at one or both ends of cell

60
Q

Peritrichous

A

flagellum spread over the entire surface

61
Q

What are the different types of directed movement that is seen in bacteria and archaea?

A
  • flagellar: best in liquid
  • spirochete: corkscrewing best used in viscous liquid
  • twitching/gliding: best used on hard surface, flagella not likely to be present
62
Q

What is chemotaxis?

A

movement toward chemical attractants and away from harmful substances

63
Q

What will cause a bacterium/cell to move, via chemotaxis?

A
  • temperature change
  • light
  • oxygen
  • osmotic pressure
  • gravity
64
Q

In what direction do most flagella rotate in order to produce a forward movement? A tumbling type movement?

A
  • counterclockwise

- clockwise

65
Q

How does the flagella rotate and produce movement?

A
  • proton gradient flows from periplasmic space into the cytoplasm between MotA and MotB
66
Q

True/ False

The twitching and gliding motility is used on solid surfaces, and could potentially require help from type IV pili and S layers.

A

False.

twitching and gliding can have help from type IV pili and slime

67
Q

What is the best way to describe a bacterial endospore?

A
  • this complex, dormant structure is formed by some bacteria, when growth conditions are not optimal.
68
Q

Is the bacterial endospore very hardy?

A

-yes, it is able to resist heat, radiation, chemicals, and desiccation and is formed within the mother cell.

69
Q

Is endospore formation considered to be replication?

A

no, one bacterium is being conserved and then one bacterium is being released

70
Q

Why is the endospore so resistant to a variety of environmental factors?

A

Presence of:

  • calcium
  • small acid soluble DNA binding proteins
  • dehydrated core
  • DNA repair enzymes
  • spore coat.
71
Q

Sporulation

A
  • endospore formation of up to 10 hours.
  • begins when nutrients dwindle
  • incorporate keratin to improve resistance of the spore coat over time.

Microbiology (14 decks)

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