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microbio 3810 > 2. prokaryotic cell structure > Flashcards

2. prokaryotic cell structure Flashcards

1
Q

are prokaryotes bigger or smaller than eukaryotes?

A

smaller

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2
Q

how many chromosomes do prokaryotes have and what shape are most of the chromosomes?

A

one; circular

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3
Q

since prokaryotes do not have a nucleus, where are the chromosomes found?

A

nucleoid region

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4
Q

T/F: prokaryotes have membrane0bound organelles

A

false

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5
Q

T/F: prokaryotes have a more complex cell envelope than eukaryotes

A

true - made of membrane, cell wall and bacterial capsule

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6
Q

what process do prokaryotes use in order to reproduce?

A

binary fission

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7
Q

what was the first macro bacteria that was seen by the naked eye back in 1999?

A

thiomargarita namibiensis

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8
Q

this is where the DNA of bacteria is packaged without being surrounded by a membrane

A

nucleoid

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9
Q

how is DNA stabilized in the nuceloid region?

A

By the neutralization of the negative charge of the DNA by small polyamines (have +ve charge) and Mg2+ ions.
- histone like proteins (maintain DNA architecture and regulation DNA transactions such as replication, recombination/repair and transcription)

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10
Q

what are the TWO main functions of the prokaryotic cell envelope?

A
  1. protection - from hostile environments such as osmolarity, and harsh chemicals and antibiotics)
  2. pathogenicity - contribute to the invasiveness of pathogenic bacteria
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11
Q

list the three layers that make up the cell envelope

A
  1. cell membrane (all bacteria have cell membranes)
  2. cell wall (all bacteria except 1 species has a cell wall)
  3. the capsule (not all bacteria have capsules)
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12
Q

this is composed of a phospholipid bilayer and proteins including integral proteins which float in the bilayer and peripheral proteins that are associated on the inner membrane surface

A

cell membrane

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13
Q

these are lipid molecules that play a role in the fluidity of the membrane

A

hopanoids

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14
Q

when the temperature increases, the fluidity of the cell membrane also increases. therefore, more things can enter the bacteria. a result of this will be _____ (more/less) hopanoids produced to stabilize temperature

A

more

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15
Q

what are the functions of the cell membrane

A
  • permeability and transport
  • electron transport and oxidative phosphorylation
  • excretion of hydrolytic exoenzymes and pathogenicity proteins
  • biosynthetic functions
  • chemotactic systems
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16
Q

this type of transport across the cell membrane relies on diffusion from high concentration to low concentration

A

passive transport

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17
Q

this type of passive transport requires NO energy or proteins

A

simple diffusion

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18
Q

this type of passive transport requires the use of channel proteins in order to transport molecules such as O2, CO2, H2O, and glycerol

A

facilitated diffusion

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19
Q

this type of transport across the cell membrane requires energy and transport proteins to travel from low concentration to high concentration

A

active transport

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20
Q

this type of transport across the cell membrane requires energy (ATP) to phosphorylate the molecule during the transport process and then use it in metabolism; use to uptake sugars by bacteria where the source of energy is from phosphoenolpyruvate (e.g. glucose and mannose)

A

group translocation

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21
Q

using specialized molecules such as siderophores to transport iron which is locked up in nature as Fe(OH)3, and insoluble and unavailable for transport

A

special transport processes

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22
Q

these are small molecular iron chelators that are produced by microbes and whose function is to sequester iron from the host and provide this essential metal nutrient to the microbe

A

siderophore

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23
Q

this function of the cell membrane is an analog function to the mitochondria function in eukaryotes

A

electron transport and oxidative phosphorylation

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24
Q

this function of the cell membrane contains six pathways of protein secretion, names type I - the VI secretion systems; used to secrete hydrolytic enzymes and pathogenicity toxins and other proteins

A

excretion of hydrolytic exoenzymes and pathgenicity proteins

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25
Q

this function of the cell membrane explains that the cell membrane is the site of the enzymes of phospholipids and cell wall biosynthesis

A

biosynthetic functions

26
Q

this function of the cell membrane relates to the cell membrane having specific receptors that can bind to different kinds of attractants and repellants

A

chemotactic systems

27
Q

this is a structural support that surrounds the cell in order to protect it. it
- gives shape to the cell and protects it from cell lysis
- protects the cell from toxic substances
- has components that contribute to the bacteria pathinogenicity
- is the site of action of several antibiotics

A

cell wall

28
Q

what are the two different groups of bacteria based on their cell walls

A

gram-negative bacteria and gram-positive bacteria

29
Q

do gram-negative or gram-postive bacteria have a thicker peptidoglycan sheet?

A

gram-positive

30
Q

do gram-negative or gram-positive bacteria contain an outer membrane and a cell membrane

A

gram-negative

31
Q

do gram-negative or gram-positive bacteria contain lipoteichoic acid and teicehoic acid

A

gram-positive

32
Q

this portion of the cell wall is responsible for its strength

A

peptidoglycan layer

33
Q

what are the three parts of the peptidoglycan layer?

A
  1. the backbone - consisting of alternating sugar derivatives NAG and NAM
  2. a set of identical tetra peptide side chains attached to NAM
  3. peptide cross-links or inter bridges
34
Q

what are the two special components of gram-positive cell walls

A
  1. teichoic acids
  2. polysaccharides
35
Q

these are partially responsible for the negative charge of the cell surface of gram-positive cell wall. they constitute major surface antigens of gram-positive bacteria

A

teichoic acids

36
Q

what are the two different types of teichoic acids in gram-positive bacteria cell walls?

A

wall teichoic acids (WTA) and lipoteichoic acid (LTA)

37
Q

in streptococcus pyogens (gram positive bacteria), what facilitates the attachment to host cells

A

LTA and M proteins

38
Q

in some species, like those with gram-positive cell walls, sugars such as mannose, arabinose and glucuronic acid exist as subunits of _______ in the cell wall

A

polysaccharides

39
Q

what are the special components of gram-negative cell walls

A
  1. outer membrane
  2. lipopolysaccharide
  3. porin channels
  4. lipoprotein
  5. the periplasmic space
40
Q

this component of gram-negative cell walls is a bilayer structure. the outer edge contains lipopolysaccharides and channel proteins

A

outer membrane

41
Q

this component of gram-negative cell walls consists of glycolipids (lipid A) and polysaccharides and it prevents the diffusion of hydrophobic materials (toxic compounds) through the outer membrane

A

lipopolysaccharide

42
Q

this is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria

A

lipid A

43
Q

this is attached to the core polysaccharide and extends from the core out into the environment. it consists of repeating oligosaccharide subunits made up of three to five sugars; it renders additional protection from the antimicrobial action of certain antibiotics

A

o antigen

44
Q

this portion of the cell wall permits the passive diffusion of low molecular weight hydrophilic compounds, such as sugars, amino acids and certain ions

A

porin channels

45
Q

large antibiotic molecules (such as beta lactams) have very ____ permeability therefore gram-negative bacteria have resistance to some antibiotics

A

low

46
Q

this portion of the cell wall cross links the outer membrane and peptidoglycan layers to stabilize and anchor the outer membrane layer; it is the most abundant protein of gram-negative cells

A

lipoprotein

47
Q

this is the space between the inner and outer membranes and the peptidoglycan layers

A

periplasmic space

48
Q

if a gram-stained cell is stained purple what kind of bacteria is it?

A

gram positive

49
Q

what are some examples of gram positive bacteria

A

bacillus, staphylococcus, streptococcus

50
Q

if a gram-stained cell is stained red what type of bacteria is it

A

gram-negative

51
Q

some bacteria such as mycobacteria tuberculosis have cell walls that contain large amounts of waxes called ____________. these cannot be stained with gram stains

A

mycolic acids

52
Q

T/F; bacteria that contain cell walls with mycolic acids are resistant to antibiotics and many harsh chemicals including detergents and strong acids

A

true

53
Q

this type of bacteria have no cell wall and contain no peptidoglycan. they are genetically closer to gram-positive bacteria; they are resistant to cell-wall inhibiting antibiotics (e.g. penicillins and cephlosporins)

A

mycoplasmas

54
Q

this is an enzyme that attacks cell walls
- found in human secretions (tears, saliva and nasal secretions)
- break down the peptidoglycan backbone

A

lysozymes

55
Q

T/F: the outer membrane of gram-negative cell walls prevents access to lysozyme therefore gram negative more resistant

A

true

56
Q

this is an enzyme that attacks cell walls
- secreted by the bacteria itself to catalyze the degradation and turnover of peptidoglycan, to participate in cell wall growth and cell separation
- responsible for the dissolution of dead cells (autolysis)

A

autolysins hydrolytic enzymes

57
Q

this is an enzyme that attacks cell walls
- these degrade bacterial cell walls and digest whole bacteria
( such as protozoa and the phagocytic cells of animals )

A

hydrolytic enzymes of higher organisms

58
Q

this is an extracellular layer lying outside the cell, composed mainly of polymer of polusaccharides

A

capsule

59
Q

how does the capsule contribute to the invasiveness of pathogenic bacteria?

A
  • encapsulated bacteria are protected from phagocytosis
  • the glycocalyx plays a role in the adherence of bacteria to the host cells (e.g. streptococcus mustans adhere tightly to the tooth surface by its glycocalyx trapping other bacterial cells of the same or different species which from the plaque on the tooth and then acid products are excreted by these bacteria causing dental caries)
59
Q

how does the capsule contribute to the invasiveness of pathogenic bacteria?

A
  • encapsulated bacteria are protected from phagocytosis
  • the glycocalyx plays a role in the adherence of bacteria to the host cells (e.g. streptococcus mustans adhere tightly to the tooth surface by its glycocalyx trapping other bacterial cells of the same or different species which from the plaque on the tooth and then acid products are excreted by these bacteria causing dental caries)

microbio 3810 (16 decks)

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