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Vet Microbio > Bacterial Cell Structure > Flashcards

Bacterial Cell Structure Flashcards

1
Q

what is arrangement determined by?

A

the plane of division and by separation/lack of separation

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2
Q

what are the seven shapes of bacteria?

A
  1. coccus
  2. coccobacillus
  3. bacillus
  4. vibrio
  5. spirillum
  6. spirochete
  7. pleomorphic
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3
Q

cocci characteristics

A

diplococci- pairs
streptococci- chains
staphylococci- grape-like clusters
tetrads- 4 cocci in a square
sarcinae- cubic configuration of 8 cocci

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4
Q

bacilli characteristics

A

rods
coccobacilli- very short rods

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5
Q

vibrios

A

resemble rods, comma shaped

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6
Q

spirilla

A

rigid helices

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7
Q

spirochetes

A

flexible helices

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8
Q

mycelium

A

network of long, multinucleate filaments

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9
Q

pleomorphic

A

organisms that are variable in shape

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10
Q

what is the smallest type of bacteria?

A

mycoplasma

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11
Q

what is the largest bacteria?

A

Epulopiscium fishelsoni

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12
Q

Protoplast

A

the plasma membrane and everything within

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13
Q

cytoplasm

A

material bounded by the plasma membrane

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14
Q

cytosol

A

liquid portion of cytoplasm; does not include genetic material, ribosomes, etc.

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15
Q

inclusions

A

granules of organic or inorganic material that are stockpiled by the cell for future use
some are enclosed by a single-layered membrane

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16
Q

ribosomes

A

complex protein/RNA structures
-sites of protein synthesis
-bacterial and archaea ribosomes are 70S
-eukaryotes are 80S

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17
Q

what does 16S mean?

A

working with microbes

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18
Q

nucleoid

A

usually not membrane bound
location of chromosome and associated proteins
usually 1 closed circular, double stranded molecule
supercoiling and nuclei proteins aid in folding

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19
Q

plasmids

A

extrachromosomal DNA that is found in bacteria, archaea, and some fungi
usually small, closed circular DNA molecules

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20
Q

how do plasmids exist and replicate?

A

independently of chromosome
inherited during cell division

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21
Q

what is the function of plasmids?

A

to confer selective advantages to host

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22
Q

what are some of the benefits of plasmids?

A

antibiotic resistance, extreme temp adjustment, utilization of nutrients, reproduce quicker, increase metabolism

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23
Q

what are the functions of the plasma membrane?

A

encompasses the cytoplasm
selectively permeable barrier
interacts with external environment

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24
Q

how does the plasma membrane interact with the external environment?

A

receptors for detection of and response to chemicals in surroundings
transport systems
metabolic processes

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25
what are amphipathic lipids?
polar ends and non-polar tails that make up the lipid bilayers
26
peripheral membrane proteins characteristics
loosely connected to membrane and easily removed
27
integral membrane protein characteristics
amphipathic- embedded within membrane carry out important functions
28
peptidoglycan
rigid structure that lies just outside the cell plasma membrane mesh-like polymer of two alternating sugars forming long strands
29
what are the two alternating sugars that form the long strands of peptidoglycan?
NAG and NAM
30
what are the two types of cell wall?
gram-positive and gram-negative
31
what are the characteristics of gram-positive cell walls?
stain purple; thick peptidoglycan
32
what are the characteristics of gram-negative cell walls?
stain pink or red; thin peptidoglycan and outer membrane
33
functions of the cell wall
maintains the shape of the bacterium helps protect cell from osmotic lysis helps protect from toxic materials may contribute to pathogenicity
34
gram positive cell walls
composed primarily of peptidoglycan may contain teichoic acids, making it negatively charged can have layers of proteins on surface of peptidoglycan
35
what do teichoic acids do to gram-positive cell walls?
give cell negative charge help maintain cell envelope protect from environmental substances may bind to host cells
36
periplasmic space in gram positive bacteria
lies between plasma and cell wall and is smaller than that of gram-negative has relatively few proteins
37
gram-negative cell wall characteristics
more complex than gram positive consist of a thin layer of peptidoglycan surrounded by an outer membrane outer membrane composed of lipids, lipoproteins, and lipopolysaccharides in stead of teichoic acids
38
how does the periplasmic space of gram-negative cells differ from that of gram-positive cells?
may constitute 20-40% of cell volume there are many enzymes present- hydrolytic enzymes, transport proteins, and other proteins
39
what connects the outer membrane to peptidoglycan in gram-negative cell walls?
Braun's lipoproteins
40
what are the three parts of lipopolysaccharides?
1. lipid A embedded in outer membrane 2. core polysaccharide 3. O side chains (antigen) that extend out from the cell
41
what is the importance of LPS?
contributes to the negative charge on cell surface helps stabilize outer membrane structure may contribute to attachment to surfaces and biofilm formation creates a permeability barrier protection from host defenses (O antigen) can act as an endotoxin (lipid A)
42
what causes people to get sick from Ecoli 0157?
the O antigen
43
what makes up the glycocalyx?
capsule and slime layers
44
what is the function of the capsule layer?
aids in attachment to solid surfaces such as biofilms in plants and animals
45
capsule layer characteristics
usually composed of polysaccharides well organized and not easily removed from the cell visible in light microscope provides protective advantages
46
what are the protective advantages of the capsule layer?
resistant to phagocytosis protect from desiccation exclude viruses and detergents
47
what are the slime layers?
similar to capsules except diffuse, unorganized, and easily removed may aid in motility
48
what are the S layers?
regularly structured layers of protein or glycoprotein that self-assemble
49
how does the S-layer differ between Gram-negative and Gram-positive bacteria?
gram-negative: the S layer adheres to the outer membrane gram-positive: it is associated with the peptidoglycan surface
50
what are the functions of the S layer?
Protect from ion and pH fluctuations, osmotic stress, enzymes, and predation maintains shape and rigidity promotes adhesion to surfaces protects from host defenses potential use in nanotechnology
51
what are the three external structures that can extend beyond the cell envelope?
pili, fimbriae, and flagella
52
what is the function of fimbriae?
short, thin, hairlike appendages that can mediate attachment to surfaces, assist with motility, and facilitate DNA uptake
53
what are the functions of sex pili?
genes for formation are found on plasmids required for conjugation
54
what are the flagella?
threadlike, locomotor appendages that extend outward from the plasma membrane and cell wall
55
what are the functions of flagella?
motility and swarming behavior attachment to surfaces may be virulence factors
56
what are the three parts of the ultrastructure?
filament, basal body, and hook
57
what are the patterns of flagella distribution?
monotrichous polar flagellum amphitrichous lophotrichous peritrichous
58
monotrichous
one flagellum
59
polar flagellum
flagellum at end of the cell
60
amphitrichous
one flagellum at each end of the cell
61
lophotrichous
cluster of flagella at one or both ends
62
peritrichous
spread over entire surface of the cell
63
chemotaxis
move toward chemical attractants such as nutrients, away from harmful substances
64
what do bacteria move in response to?
temperature, light, oxygen, osmotic pressure, and gravity
65
which direction rotation causes forward motion (run)?
counterclockwise
66
which direction rotation causes the cell to stop and tumble?
clockwise
67
spirochete motility
multiple flagella form axial fibril which winds around the cell remain in periplasmic space inside outer sheath corkscrew shape exhibits flexing and spinning movements
68
twitching motility
pili at ends of cell short, intermittent, jerky motions cells are in contact with each other and surface
69
gliding motility
smooth movements
70
what are bacterial endospores?
complex, dormant structures formed by some bacteria in various locations within the cell
71
what are bacterial endospores resistant to?
heat, radiation, chemicals, desiccation
72
what is the structure of an endospore?
spore is surrounded by thin covering called exosporium thick layers of protein form the sore coat the cortex beneath the coat is made of thick peptidoglycan the core has nucleoid and ribosomes
73
sporulation process
1. DNA replicates 2. Membranes form around the DNA 3. Forespore forms additional membranes 4. Protective cortex forms around the spore 5. Protein coat forms around the cortex 6. Spore is released
74

Vet Microbio (12 decks)

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