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Microbiology Unit 1 > Prokaryote Cell Structure > Flashcards

Prokaryote Cell Structure Flashcards

1
Q

What five items constitute basic prokaryotic cell structure?

A
  1. Cytoplasmic membrane
  2. Cell wall
  3. Capsule or slime layer
  4. Filamentous protein appendages
  5. Internal structures
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2
Q

Capsules and slime layers are types of . . . .

A

Glycocalyx

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3
Q

What are two examples of filamentous protein appendages?

A
  1. Flagella

2. Pili

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4
Q

Name five prokaryotic internal structures.

A
  1. Chromosomes
  2. Ribosomes
  3. Plasmids
  4. Storage granules
  5. Endospores
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5
Q

What are the 2 main functions of prokaryotic membrane proteins?

A
  1. Receptors

2. Transport gates

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6
Q

What are the 3 roles of the cytoplasmic membrane?

A
  1. Define cell boundary
  2. Semi-permeable barrier
  3. Site of energy production (e- transport chain)
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7
Q

Which 3 types of molecules pass through the cytoplasmic membrane via simple diffusion?

A
  1. Water
  2. Some gasses
  3. Small hydrophobic (non polar) molecules
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8
Q

What is osmosis?

A

The ability of water to flow freely across the cytoplasmic membrane.

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9
Q

What cases water to flow into or out of a cell?

A

Water flows into areas of higher solute concentrations in an attempt to equalize them.

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10
Q

What tonicity do prokaryotes usually grow in, and what is the result?

A

Prokaryotes usually live in hypotonic locations. Water flowing into the cell exerts hydrostatic pressure, but the cell wall keeps the cell from bursting.

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11
Q

What will result from a damaged bacterial cell wall?

A

The cell will lyse.

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12
Q

What is facilitated diffusion?

A

Impermeable compound movement across a membrane by EXPlOITING a concentration gradient.

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13
Q

How can facilitated diffusion alter a concentration gradient?

A

It can lower or eliminate a gradient, but not create one.

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14
Q

How much energy is required for Glycerol to enter an E. coli bacterium? What type of transport is it?

A

No energy is expended for facilitated diffusion of Glycerol across an E. coli membrane.

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15
Q

What is active transport?

A

Impermeable compound movement across a cell membrane, AGAINST a concentration gradient.

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16
Q

What are the three primary mechanisms of active transport in prokaryotes?

A
  1. Proton motive force
  2. ATP binding cassette system
  3. Group translocation
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17
Q

How does proton motive force work?

A
  1. Transporters allow protons (H+) to enter

2. Protons either bring in or expel other substances

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18
Q

The permease that transports lactose into bacteria is an example of which kind of active transport?

A

Proton motive force

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19
Q

Efflux pumps in antibiotic- resistant bacteria use what kind of active transport?

A

Proton motive force

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20
Q

What is the ATP Binding Cassette System (ABC transport)?

A

Bacteria sometimes uses binding proteins to scavenge and deliver molecules to transport complex.

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21
Q

Maltose transport is an example of what type of active transport?

A

ATP Binding Cassette System

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22
Q

What is group translocation?

A

An active transport mechanism that chemically alters a molecule during passage. [Uptake of molecule does not alter concentration gradient.]

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23
Q

The phosphotransferase system is an example of which type of active transport?

A

Group Translocation

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24
Q

Describe how glucose enters a cell, driven by insulin?

A

Glucose utilizes group translocation. The sugar molecule is phosphorylated during transport. The molecular alteration means that the concentration gradient does not change.

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25
Q

Where is the site of energy production?

A

The cytoplasmic membrane.

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26
Q

How is energy produced on the cytoplasmic membrane?

A

The electron transport chain involves a series of embedded proteins. The proteins are used to form a proton motive force. The energy produced is used to drive transport mechanisms or to create ATP.

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27
Q

What is the rigid structure surrounding the cell membrane called?

A

The cell wall

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28
Q

What are two functions of the cell wall?

A
  1. Determines shape of cell

2. Prevents cell from lysing

29
Q

Which chemical lends itself to the rigidity of the cell wall?

A

Peptidoglycan (PTG)

30
Q

Describe the basic prokaryotic cell wall structure.

A

Alternating series of NAG and NAM, joined to form Glycan Chains. Glycan chains are held together by a string of 4-amino acids called a Tetrapeptide Chain.

31
Q

Describe the two main components of a G+ cell wall.

A
  1. Relatively thick layer of PTG (<30 layers)

2. Teichoic Acid (gives cell a negative charge)

32
Q

Give a description and location of PTG in a G- cell.

A

PTG is in a thin layer, sandwiched between an outer membrane and the cytoplasmic membrane.

33
Q

What is a Gram- outer membrane composed of?

A

It is a lipid bilayer (made of lipopolysaccharide), called LPS.

34
Q

What is the region between the outer membrane and cytoplasmic membrane called?

A

The periplasm

35
Q

Where are the binding proteins of ABC transport system located in G- bacteria?

A

The periplasm

36
Q

Where are most secreted proteins contained in G- bacteria, unless transported across outer membrane?

A

The periplasm

37
Q

What differences in G+ and G- cell walls account for differences in staining characteristics?

A
  1. Gram-positive bacterium retain crystal violet-iodine complex of Gram stain
  2. Gram-negative bacterium lose crystal violet-iodine complex
38
Q

Which antimicrobials interfere with the synthesis of PTG?

A
  1. Penicillin

2. Lysozymes

39
Q

How does Penicillin fight bacteria?

A

Binds proteins involved in cell wall synthesis and prevents cross-linking of glycan chains by tetrapeptides

40
Q

Is Penicillin more effective against G+ or G- bacteria? Why?

A

More effective against Gram+ bacteria, because it can’t cross outer membrane.
[Penicillin derivatives produced to protect against G-.]

41
Q

Where are Lysozymes produced?

A

In many body fluids including tears and saliva

42
Q

How do Lysozymes fight bacteria?

A

They break bonds linking NAG and NAM

43
Q

Which bacterium naturally lacks a cell wall? How is its membrane strengthened?

A

Mycoplasma contain sterols in membrane

44
Q

What does Mycoplasma bacterium cause?

A

Mild pneumonia

45
Q

What do Archea contain instead of peptidoglycan?

A

Pseudopeptidoglycan

46
Q

What are the 2 Layers External to the Cell Wall?

A

Capsule and Slime layer

47
Q

What is a capsule?

A

A distinct gelatinous layer surrounding a bacterium

48
Q

What is a slime layer?

A

An irregular diffuse layer

49
Q

What are the 2 general functions of slime layers and capsules?

A
  1. Protection from host defenses

2. Enables bacteria to adhere to specific surfaces

50
Q

What are most slime layers and capsules made of?

A

Polysaccharide, referred to as glycocalyx

Glyco = sugar calyx = shell

51
Q

Xanthomonas campestris produces a slime layer used to make what?

A

Xanthan gum, used as a gelling and stabilizing agent in salad dressings, ice creams, toothpastes, etc.

52
Q

What are 2 types of Filamentous Protein Appendages?

A

Flagella and Pili

53
Q

What are flagella?

A

Long protein structure, responsible for motility (propeller like movements to push bacteria, Chemotaxis)

54
Q

How can flagellar location aid in identification of a bacterium?

A

E. coli have flagella over entire surface (peritrichous) while others have a polar flagellum (monotrichous)

55
Q

How do pili compare to flagella?

A

They are considerably shorter and thinner than flagella.

56
Q

What are the 3 functions of pili?

A
  1. Attachment - these pili called fimbriae
  2. Movement – twitching motility
  3. Conjugation - Mechanism of DNA transfer (ex F-pilus)
57
Q

What are the two prokaryotic Genetic Internal Structures?

A
  1. Chromosome

2. Plasmid

58
Q

What are 4 characteristics of prokaryotic chromosomes?

A
  1. Resides in cytoplasm, in nucleoid space
  2. Typically single chromosome
  3. Circular double-stranded molecule
  4. Contains all genetic information
59
Q

What are 3 features of Plasmids?

A
  1. Circular DNA molecule (0.1% to 10% size of chromosome)
  2. Extrachromosomal (Independently replicating)
  3. Encode characteristic that potentially enhances survival (ex Antimicrobial resistance)
60
Q

What is the ribosome’s function?

A

Protein synthesis

61
Q

What do ribosomal subunits consist of?

A

riboprotein and ribosomal RNA

62
Q

What size are Prokaryotic ribosomal subunits?

A 
Large = 50S
Small = 30S
Total = 70S
63
Q

How do prokaryotic ribosomes differ from eukaryotic ones, and what is the significance?

A

Prokaryotic ribosomes are smaller, and that difference is often used as target for antimicrobials

64
Q

What are endospores?

A

Dormant cell types, produced through sporulation

~ Theoretically remain dormant for 100 years

65
Q

When does endospore germination occur?

A

After exposure to heat or chemicals

66
Q

How are Vegetative cells produced from endospores?

A

Through germination (not a source of reproduction)

67
Q

What was Robert Koch was able to establish?

A

endospore role in disease transmission (Bacillus anthracis)

68
Q

What did Tyndall attribute contamination issues in Pasteur’s experiments to?

A

Heat resistant life form, called endospore

Microbiology Unit 1 (11 decks)

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