L2/3: Microbial Cell Structure and Function Flashcards
1
Q
What type of cells are Bacteria?
A
prokaryotic
2
Q
What type of habitats do bacteria exist in?
A
terristrial and aquatic
3
Q
How do Bacteria reproduce?
A
asexual (binary fission)
4
Q
What’s the size range of Bacteria?
A
0.3 µm to 100 µm
5
Q
What is the average size of Escherichia coli?
A
4 µm
6
Q
What is the average size of Thiomargarita?
A
> 100 µm
7
Q
What is the shape of coccus cells?
A
round/ sphere
8
Q
What are pairs of coccus called?
A
diplococcus
9
Q
What are chains of coccus called?
A
streptococcus
10
Q
What are grape-like clusters of coccus called?
A
staphylococcus
11
Q
What are 4 cocci in a square called?
A
tetrads
12
Q
What is the shape of bacillus cells?
A
rod-shaped bacteria
13
Q
What are curved rods called?
A
vibrio
14
Q
What are rigid helix cells called?
A
spirillum
15
Q
What are flexible helix cells called?
A
spirochete
16
Q
What are cells with variable shapes called?
A
pleomorphic
17
Q
What are hyphae?
A
long filaments that can grow on bacteria and fungi
18
Q
What is a network of hyphae called?
A
mycelium
19
Q
What’s the advantage of being small for cells?
A
higher surface to volume ration (S/V) which allows for more efficient nutrient uptake and faster growth
20
Q
What are the main functions of the plasma membrane in bacteria?
A
selectively permeable barrier
nutrient and waste transport
location of many metabolic process (respiration, photosynthesis)
detection of environmental cues (signal transduction systems)
21
Q
What are the main functions of gas vacuoles in bacteria?
A
provides buoyancy for floating in aquatic environments
22
Q
What are the main functions of ribosomes in bacteria?
A
protein synthesis (translating mRNA to protein)
23
Q
What are the main functions of inclusions in bacteria?
A
storage of C, P, and other substance
site of chemical reactions (microcompartments)
movement
24
Q
What are the main functions of periplasmic space in bacteria?
A
Space between the plasma membrane and peptidoglycan
gram + : typically smaller or absent
gram - : contains hydrolytic enzymes and binding proteins for nutrient processing and uptake
25
What are the main functions of the cell wall in bacteria?
protection from osmotic stress
| helps maintain cell shape
26
What are the main functions of capsules and slime layers in bacteria?
resistance to phagocytosis
| adherence to surfaces
27
What are the main functions of fimbriae and pili in bacteria?
attachment to surfaces
bacterial conjugation and transformation
twitching
28
What are the main functions of flagella in bacteria?
swimming and swarming motility
29
What are the main functions of endospores in bacteria?
survival under harsh environmental conditions
30
What are 3 common features of bacterial cell organization?
cell envelope
cytoplasm
external structures
31
What is the bacterial cell envelope made up of?
plasma membrane, cell wall, and layers outside the cell wall
32
What does amphipathic mean?
has both hydrophobic and hydrophilic parts
33
What stabilizes plasma membranes of eukaryotic cells but is often absent in bacterial plasma membranes?
sterols
34
What are hopanoids?
sterol-like molecule in bacteria that stabilizes the plasma membrane (found in petroleum)
35
Describe the bacterial cell wall
rigid, lies just outside the plasma membrane
36
Gram + stain ____
| Gram - stain ____
purple
| pink
37
What is an important component of the cell wall that determines if the cell is gram -/+?
peptidoglycan
38
What is peptidoglycan?
polysaccharide formed by 2 alternating sugars (NAG and NAM) and cross-linked by peptides of alternating D- and L- amino acids
39
What gives strength to peptidoglycan?
peptides are cross-linked
40
What is transpeptidation?
reaction forming cross-links between peptides
41
What antibiotic interrupts transpeptidation?
penicillin
42
What are the 2 types of peptide cross-links?
direct and indirect
43
peptide interbridges are present in what type of cross-links?
indirect
44
How do gram + and gram - cell walls differ?
Gram + are thick and have multiple layers of peptidoglycan
| Gram - are thinner and have a single layer of peptidoglycan and an additional outer membrane
45
What makes up gram-positive cell walls
primarily peptidoglycan
| teichoic acids that provide stability
46
What makes up gram-negative cell walls
```
thin layer of peptidoglycan surrounded by outer membrane of:
lipids
lipopolysaccharide (LPS)
porins that form channels in outer membrane
```
47
What are the 3 parts of LPSs
lipid A
core polysaccharide
O side chain (O antigen)
48
What is the importance of LPS
protection from host defenses
attachment
stability
49
What part of LPS can act as a toxin (endotoxin)
lipid A
50
What are possible layers outside the bacterial cell wall?
Capsules (organized, not easily removed)
Slime (not organized, easily removed)
S layer (organized)
51
What type of the layer outside the cell wall is a protein?
S layer
52
What are the functions of the layer outside the cell wall?
attachment
| protection from chemicals, harsh environments, bacterial viruses, and host immune responses
53
What is the substance in which inclusions, chromosomes, and ribosomes are suspended in bacteria?
cytoplasm
54
What inclusions store carbon?
glycogen, PHB granules
55
What inclusion stores phosphate?
polyphosphate granules
56
What inclusion stores sulfur?
Sulfur globules
57
What inclusions store carbon and nitrogen?
cyanophycin granules
58
What's an example of a phylum that has gas vacuoles
Cyanobacteria
59
What are magnetosomes?
inclusions that contains iron particles in the form of magnetite (Fe3O4) or greigite (Fe3S4)
help bacteria orient themselves in Earth's magnetic field
60
What phylum of bacteria has photosynthetic membranes with chlorophyll?
Cyanobacteria
61
What are microcompartments?
compartments in cytoplasm with specialized functions
62
What do carboxysomes have inside of them?
2 enzymes- carbonic anhydrase and RubisCO
63
What is an example of a micro compartment that is often found in Cyanobacteria and other CO2 fixing bacteria?
carboxysomes
64
What does carbonic anhydrase do?
converts carbonic acid to CO2
65
What does RubisCO do?
adds CO2 to RuBP to form PGA
66
What is the energy source for CO2 fixation?
photosynthesis
67
Where does transcription occur in prokaryotes?
cytoplasm
68
Where does translation occur in prokaryotes?
cytoplasm
69
What does RNA polymerase do?
transcribe DNA to mRNA
70
What two process often occur simultaneously in bacteria and archaea?
transcription and translation
71
What is the nucleoid
non-membrane enclosed region in bacteria containing the chromosome
72
Where are plasmids found?
cytoplasm of bacteria
73
What are plasmids?
small, closed circular DNA that replicate independently of chromosome
74
What are conjugative plasmids?
plasmid that can transfer from one bacteria to another through conjugation
75
What are R plasmids?
plasmids that encode resistance
76
What are the general functions of the external structures of bacteria?
attachment
horizontal gene transfer
movement
77
What are pili?
thin, protein appendages that help with attachment
78
What are sex pili used for?
conjugation
allow for transferring of genetic information
form of horizontal gene transfer
79
What are Type IV pili used for?
twitching motility (cycles of extension, attachment, and retraction)
80
What are monotrichous bacteria?
one flagellum
81
What are polar flagellum?
flagellum at end of cell
82
What are amphitrichous bacteria?
one flagellum at each end of cell
83
What are lophotrichous bacteria?
cluster of flagella at one or both ends
84
What are peritrichous bacteria?
flagella spread over entire surface of cell
85
What is an example of a bacteria species that is peritrichous?
E. coli
86
What are the 3 components of a flagellum?
filament, hook, and basal body
87
What makes up the filament of flagellum
many copies of a protein called flagellin
88
What is the part of the flagellum that sticks out the end and rotates?
filament
89
What is the middle part of the flagellum that is slightly flexible?
hook
90
What is the bottom of the flagellum called that acts as the "engine"?
basal body
91
CCW rotation of the flagellum causes what kind of motion?
forward (run)
92
CW rotation of the flagellum causes what type of motion?
disrupts run, causing it to stop and tumble
93
What is chemotaxis?
sensory system that enable microbes to move toward or away from specific chemicals- requires coordination of flagellum movement
94
What are chemoreceptors?
receptors that are part of chemotaxis, are in the membrane, and that sense and respond to different attractants and repellants
95
What is random walk?
combination of runs and tumbles of flagella movement that occurs when there is no attractant
96
What is biased random walk?
combination of runs and tumbles that propels bacteria up gradient of attractant
occurs when chemoreceptors detect attractant
97
What type of cells are Archae?
prokaryotic
98
What type of reproduction are Archaea capable of?
asexual
99
What environments are archaea found in?
terrestrial and aquatic (also human skin and gut)
100
What type of genetic material do archaea have?
circular dsDNA chromosomes and plasmids
101
What unit is used to measure the size of Archae?
µm
102
```
Do Archaea have:
plasma membranes?
cell walls?
peptidoglycan?
S layers?
Slime layers?
Capsules?
Flagella?
```
```
yes
some
no
some
some
some
some
```
103
What are methanogens?
Archaea that produce methane
104
What is methanogenesis?
biological production of methane (unique to Archaea)
105
Extremophiles are in what domain of life?
Archaea
106
What are thermophiles?
extremophiles that grow between 45 and 85C
107
What are hyperthermophiles?
extremophiles that grow between 85 and 113C
108
What type of Archaea live in high salt environments?
Haloquadratum
109
What do Archaeal membranes provide?
enhanced stability for survival and growth at high temperatures
110
What are 2 ways lipids in Archaeal membranes differ from Bacterial and eukaryotic lipids?
1. contain hydrocarbons derived from isoprene (5C, branched molecules) which changes how they are branched and allows them to be more fluid
2. hydrocarbons are attached to glycerol by ether links instead of ester links, which are more resistant to chemical attack and heat
111
What's something Archaea lipid membranes can do that Bacterial and eukaryotic lipid membranes can't do?
form a monolayer or a bilayer
