Prokaryote Cell Biology Flashcards
1
Q
Define organnelles:
A
Structure or part that is enclosed within its own membrane inside a cell and has a particular function
2
Q
Where can you find organelles?
A
In eukaryotic cells
3
Q
Are organelles present in prokaryotes?
A
In general no, but some do contain structure considered to be organelles
4
Q
What are different structures in a prokaryote?
A
-Cell wall
-Ribosomes
-Plasma membrane
-Cytoplasm
-Nucleoid
-Flagellum
Pili
5
Q
What are examples of photosynthetic bacteria?
A
- Green filamentous
- Proteobacteria
- Cyanobacteria
6
Q
What do Green filamentous, Proteobacteria and Cyanobacteria contain?
A
Intracytoplasmic membrane
Thylakoid membrane compartments
Chlorosome compartments
7
Q
What do Green filamentous, Proteobacteria and Cyanobacteria have in common other than similar structures?
A
Maximise their efficiency of photosynthesis by…
- Increasing number of photosynthetic protein complexes
- Maximise size of light-exposed membrane surface
- Provide an idealised sub cellular environment for photosynthesis
8
Q
What are are planctomycetes considered to be?
A
true bacteria that contain a nuclear envelope
9
Q
Does Planctomycetes show clear compartmentalisation?
A
Yes
10
Q
What is planctomycetes DNA surrounded by?
A
Double-lipid bilayer
11
Q
What are magnetotactic bacterial?
A
- Navigate along magnetic field
- Detect magnetic field
12
Q
Who first found the magnetotatic bacterium?
A
Richard Blakemore in 1975
13
Q
Are magnetotactic bacteria Gram-negative or Gram-positive?
A
Gram-negative
14
Q
What does a magnetotactic bacteria contain?
A
-magnetosomes
15
Q
What are magnetosomes?
A
- Crystals of an iron mineral
- Magnetic
16
Q
What do bacteria use magnetosomes for?
A
Magnetotaxis
17
Q
What do magnetosomes detect?
A
Field lines of the earth
18
Q
How Manu magnetosomes are in one chain?
A
15-20
19
Q
What are the chemical name and formula of the two types of magnetosomes?
A
- Iron oxide = Fe3O4
- Iron sulfide =Fe3S4
20
Q
How are magnetosomes formed?
A
- Invagination of cytoplasmic membrane (iron pumped into periplasmic and captured in invagination)
- Accumulation of ferrous irons
- Nucleation of magneto some formation
21
Q
What is organising the magnetosome chain?
A
MamK
22
Q
What is MamK?
A
Actin-like protein that forms filaments
23
Q
What are different F-actin like fibres in prokaryotes?
A
MamK ParM AlfA Alp7A AlfA MreB
24
Q
What the function of MreB?
A
Cell shape
25
What is the function of MamK?
Organelle assembly and positioning
26
What is the function of ParM?
Plasmid Segregation
27
What is the function of Alp7A?
Cellular entering of nucleoid
28
What is the function of AlfA?
Plasmid segregation
29
How identical MreB to Actin?
15%
30
How identical is ParM to Actin?
12%
31
How identical is ParM to MreB?
11%
32
How are eukaryotic F-actin and prokaryotic actin-like similar?
In fold
Both bind to ATP
Both polymerise
33
What are MreB and Mdl1 involved in?
Bacterial morphogenesis
34
What is a characteristic of ParM?
Dynamic
35
How are ParM dynamic?
- Polymerisation of ATP-bound ParM at both ends
- ATP-hydrolysis occur spontaneously
- Unstable filament when ParM-ADP is at the end
36
What are characteristics of ParM filaments?
Segregate plasmids
37
How do ParM filaments segregate plasmids?
- ParM binds to centromeric DNA-sequence
- ParM polymerises and binds to ParR
- Filament elongation separates the plasmids
38
What is a distant prokaryotic tubule analogue?
FtsZ
39
How much sequence identity does tubule and FtsZ share?
10-18%
40
What are common features between tubule dimer and FtsZ dimer?
- GTPase activity that controls polymerisation
- Formation of protofilaments
- Similar fold
41
What forms a ring at the cell cleavage site?
FtsZ
42
What effect fo a mutant FtsZ have on cell separation?
Prevents cell from separating
43
What does FtsZ support?
Bacterial cytokinesis
44
What foes FtsZ form in living Archaea cells?
Filaments
45
Why is bacteria being small a problem?
Can not sense nutrient gradient along their cell
46
How do bacteria swim for to find their food source?
Via
- random motility
- directed motility
47
What is not sufficient to move prokaryotic cells around?
Random Browninan motion
48
Are prokaryotes actively or passively moving through or over surfaces?
Activelt
49
What are the modes of motility in prokaryotes?
- Swimming
- Swarming
- Gliding
- Twitching
50
Do swarming occur in or on the surfaces?
On the surfaces
51
What is the rate that a bacterium swims?
25-160 micrometer per second
52
What works together to propel the cell forward?
Several flagella
53
What are flagella?
Protein assembled to rotate
54
What is motility driven by?
Basal motor
55
What does a basal motor use to rotate the flagellum?
Proton gradient
56
How many rotations does flagella rotate per second?
100-300 rotations per second
57
Can flagella switch in direct?
Yes
58
What is gliding motility?
- Surface-attached motility
- Independently development mechanisms
- Some rate over secreted adhesion proteins
- Polysaccharide secretion might underly motility
59
What is twitching motility?
- Use of pilus structure
- Pilin secretion or degradation changes the length of the type IV pilus
- Change in length can be used for slow gliding over surfaces
60
What is a type of secretion-based motility?
Yes
61
What is a types of puli-based motility?
Twitching
62
What is the average rate of gliding motility?
2-5 micrometers per second
63
How many pili per cell?
100-1000
64
How long are the pili?
1-2 micrometres long
65
How wide are the pili?
2-8 nanometers
66
What is a pilus?
Straight and relatively rigid cell extensions
67
What aids DNA exchange between cells and surface adhesion?
Pili
68
Why are pili dynamic?
They can retract and grow
69
What are twitching motility used for?
Form colonies
70
Does Gram-negative or Gram-positive bacteria have complex protein translocation machines?
Gram-negative bacteria
71
How do bacteria infect a host?
Attaching to surfaces and trigger there uptake by phagocytosis
72
How many different secretion systems known?
6
73
What secretion system injects proteins?
Type 3 and type 6
74
How many proteins are there involved in secretion system?
15-30 proteins
75
What is type 3 secretion system not used for?
motility
76
What do rotation motor of flagella and type III secretion system share?
Both assemblies share homologous proteins
77
What does bacteria injecting components into host cells interfere with?
Cellular processes and suppress host defences
78
What is induces secretion of bacteria components?
Contact with host or abiotic factors
79
What are abiotic factors?
Oxygen
Calcium changes
Temperature changes
80
Wha do ring proteins assemble into (in relation to bacteria infecting host cells)?
Needle
81
What is the size of the ring of proteins?
4nm
82
What can be transported through the lumen of the needle?
Chemical/proteins (Effectors/toxins)
83
How are needles form?
ATP cleavage
Subunits get transported through channel
Build needle
84
What are various modification of the host cell can occur due to material transported through needle?
Cytoskeleton
Cell cycle
Apoptosis
Transcription
85
How does bacteria force the host cell to take them up?
Bacterial inject proteins into host cell and manipulate the actin cytoskeleton = forces uptake
86
How many type III secretion systems needles are found in a singular bacterium cell?
10-100
87
What causes acute inflammation in epithelia lining of colon?
Bacteria infection
88
What are consequences of bacteria infecting of epithelial lining of the colon?
Acute inflammation
89
How does the bacteria infect epithelial lining of the colon causing inflammation in the host cell?
By entering host cell cytoplasm and spreading inter cellularly
90
What is moving the cells?
Tail formed at rear ends of bacteria during moving
91
What is the tail consisting of at the movement of bacteria?
Fibres of F-actin
92
What experiments shows bacteria use of host actin to move in the host cytosol?
- Purify G-actin and add to reaction tube with bacteria
| - Observe bacteria and look to see if it can move inside reaction tube
93
What do in vivo and in vitro experiments demonstrate about tails of cytosolic bacteria?
Consist of F-actin
94
What helps move the bacteria through the host cell and across cell barrier?
Polar polymerisation of host actin
95
What does Listeria ActA resemble?
Host protein that triggers actin polymerisation
96
What do bacteria use to make an actin "comet tail"?
Endogenous machinery
97
What activates actin polymerisation in host cells to aid bacterium motility?
Polar bacterial proteins
98
What evidence showed that ActA mediates motility?
- Point mutation
- Lactase beads coated in ActA purified from bacteria
- ATP and Actin and other comments all put into reaction tube
- If ActA mediates motility beads will be "shooting" around
99
What does movement of bacterium allows mergence of?
Host cells
