Lecture 2- Bacterial cell structure Flashcards
1
Q
In regards to shape most bacteria can be termed?
A
Monomorphic
2
Q
T/F: Most bacteria are pleomorphic?
A
False, most bacteria are monomorphic
3
Q
Define pleomorphic.
A
Being variable in shape and lacking a single, characteristic form
4
Q
These are responsible for the characteristics of bacteria size and shape.
A
Genes
5
Q
T/F: As bacteria age they can change shape?
A
True
6
Q
List the 3 basic shapes of bacteria.
A
- bacillus
- coccus
- spiral
7
Q
Name the 3 subtypes of spiral shaped bacteria.
A
- spirillum
- vibrio
- spirochete
8
Q
These spiral shaped bacteria can have one or more twists.
A
Spirillum
9
Q
These spiral shaped bacteria look like like a curved rod
A
Vibrio
10
Q
These spiral shaped bacteria are flexible, helical spirals.
A
Spirochete
11
Q
List two shape types that are unusual for prokaryotes.
A
- Star-shaped bacteria
- rectangular bacteria
12
Q
Bacteria shape arrangement can fall under 3 categories, what are they?
A
- Pairs
- Clusters
- Chains
13
Q
Pairs of cocci or bacilli would be called what, respectively?
A
Diplococci and diplobacilli
14
Q
Clusters of cocci would be called what?
A
Staphylococci
15
Q
Chains of cocci or bacilli would be called what, respectively?
A
Streptococci and streptobacilli
16
Q
Diplococci, streptococci, diplobacilli, and streptobacilli bacteria have how many planes of division?
A
1
17
Q
Tetrad bacteria have how many planes of divisions?
A
2
18
Q
Sarcinae bacteria have how many planes of divisions?
A
3
19
Q
What are branched networks of long mulitnucleate filaments?
A
Mycelium
20
Q
Do smaller or larger bacteria cells have a greater surface area to volulme ratio?
A
Smaller cells have greater surface area to volume ratio
21
Q
What is the benefit for bacteria being smaller rather than larger?
A
Being smaller increases surface area. As this ratio increases so does the efficiency of the uptake of nutrients as well as the diffusion of other molecules within cell. In turn, this will lead to a more rapid growth rate.
22
Q
Does cell shape affect the Surface area to volume ratio?
A
Yes
23
Q
Comparing a rod with a coccus of the same volume, which will have a greater nutrient flux across its plasma membrane?
A
The rod because it will have a greater surface area to volume ratio than the coccus
24
Q
Name some functions of the bacterial pplasma membrane.
A
- selectively permeable barrier
- mechanical boundary of the cell
- nutrient and waste transport
- location of many metabolic processes
- respiration
- photosynthesis
- detection of environmental cues for chemotaxis
25
What is the function of a bacterial gas vacuole?
An inclusion that provides buoyancy for floating in aquatic environments
26
What is the function of bacterial ribosomes?
Protein synthesis
27
What are the functions of bacterial inclusions?
Storage of carbon, phosphate, and other substances
28
What is the function of the bacterial nucleoid?
localization of gentic material (DNA)
29
What is the function the periplasmic space?
* in typical gram-negative bacteria, contains hydrolytic enzmes and binding protiens for nutrient processing and uptake
* in typical gram-positive bacteria, may be small or absent
30
What is the function the bacterial cell wall?
* protection from osmotic stress
* helps maintain cell shape
31
What are the functions of bacterial capsules and slime layers?
* Resistance tophagocytosis
* adherence to surfaces
32
What are the functions of bacterial fimbriae and pili?
* Attachment to surfaces
* bacterial conjugastion and transformation
* twitching and gliding motility
33
What are the functions of bacterial flagella?
swimming and swarming motility
34
What is the function of the bacterial endospore?
survival under harsh conditions
35
Name the 3 components of the bacterial cell envelope.
1. plasma membrane
2. cell wall
3. layers outside the wall (capsule or slime layer)
36
This structure is a must have for all living organisms.
plasma membrane
37
T/F: All bacteria have internal membrane systems?
False, some do
38
T/F: Bacterial membranes are similar to eukaryotic membranes in that they are lipid bilayers and many of their amphipathic lipids are phospholipids
True
39
Bacterial membranes usually differ from eukaryotic membranes in lacking sterols (steroid-containing lipids). Instead they contain steroid-like molecules called what?
hopanoids
40
What are the functions of the hopanoids in the bacterial membranes?
They help to stabilize the membrane
41
Bacterial membrane lipid composition can vary with environmental changes such as temperature. How does this membrane lipid composition change in respons to temperature changes?
* At lower temperatures, bacteria have more unsaturated FAs in their membrane phospholipids
* At higher temperatures, bacteria have more saturated FAs in their membrane phospholipids
42
Name two ways that archaeal membranes are different from bacterial and eukaryotic membranes.
1. They are composed of lipids that differ chemically from those of bacteria and ukaryotes
2. Some have a monolayer structurs intead of a bilayer structure
43
List 2 defining characteristics of bacterial or eukaryotic membrane lipids.
1. contain ester bonds
2. have 2 hydrocarbons attached to a glycerol
44
List 3 defining characteristics of archaeal membrane lipids.
1. contain ether bonds
2. contain branched molecules
3. some are contain tetraethers
45
List 3 plasma membrnae functions.
1. It encompasses the cytoplasm
2. acts as a selectively permeable barrier
3. interacts with the external environment
* receptors for detection of and response to chemicals in surroundings
* transport systems
* metabolic processes
46
List some characteristics of the cytoplasm of bacteria and archaea.
* substance in which nucleoid, ribosomes, inclusion bodies, plasmids, and cytoskeletal filaments are suspended
* lacks membrane bound organelles
* composed of mostly water
47
T/F: Homologs of all 3 eukaryotic cytoskeletal elements have been identifed in bacteria and their functions are similar as they are in eukaryotes
True
48
FtsZ is a bacterial cytoskeletal protein that is a tubulin homolog of a eukaryotic cytoskeletal protein and it is found in many bacteria. What is it's function?
forms ring septum formation in cell division
49
MreB is a bacterial cytoskeletal protein that is an actin homolog of an eukaryotic cytoskeletal protein and it is found in bacilli, but not in cocci. What is it's function?
Maintians shape by positioning peptidoglycan synthesis machinery
50
CreS is a rare bacterial cytoskeletal protein that is an intermediate filament homolog of an eukaryotic cytoskeletal protein. What is it's function?
Maintains curve shape
51
Plasma membrane infoldings would be observed in bacteria perfoming what types of functions?
* many photosynthetic bacteria
* many bacteria with high repiratory activity
52
What is an anammoxosome and what is its function in *Plantomycetes?*
It is an organelle. It is the site of anearobic ammonia oxidation
53
What are inclusions?
granules of organic or inorganic material that are stockpiled by the cell for future use
54
What are the functions of storage inclusions?
storage of nutrients, metabolic end products, energy, and building blocks
55
List some molecules storage inclusions are responsible for.
* glycogen storage
* carbon storage
* poly-B-hydroxybutyrate (PHB)
* Glycogen
* phosphate- polyphosphate granules (volutin)
* amino acids- cyanophycin granules
* sulfur granules
56
List some characteristics of gas vacuoles.
* they are found in aquatic, photosynthetic bacteria and archaea
* they are aggregates of hollow cylindrical structures called gas vesicles
* they provide buoyancy in gas vesicles
57
List some characteristics of magnetosomes (inclusions).
* they ar efound in aquatic bacteria
* contain magnetit particles (iron) for orientation in Earth's magnetic field
* contain the cytoskeletal rotein MamK
* helps to form magnetosome chain
58
What are microcompartments?
bacterial inclusions not bound by membrane but are compartmentalized for specific functions other than storing substances
59
What are carboxysomes?
* microcompartments within many cyanobacteria and other CO2- fixing bacteria
* contian the enzyme ribulose-1,5-bisphosphate carboxylase (Rubisco). An enzyme used for CO2 fixation
60
What are the functions of ribosomes?
Protein synthesis
61
Bacterial ribosmes are know are called 70s ribosomes and are composed of what two subunits?
1. small- 30s
2. large 50s
62
Eukaryotic ribsomes are are also known as _____ ribosomes?
80s
63
Bacterial ribosomes are made up of primarily ribosomal RNA (rRNA). What types of rRNA makes up the small and large subunits?
* 16s rRNA- small subunit
* 23s rRNA and 5s rRNA- large subunit
64
If we want to treat a bacterial induced disease in humans what types of ribosomes should we target?
70s
65
What is the nucleoid?
an irregularly hsaped region that contains the cell's chromosome and associated proteins
66
List a few characteristics of the the nucleoid (4).
* It is usually not membrane bound (few exceptions)
* location of chromosome and its associated proteins
* usually 1 closed circular double-stranded DNA molecule
* contains supercoiling and nucleoid proteins (deierent from histones) that aid in folding
67
List a few characteristics of the prokaryotic chromosome (3).
1. usually a circular, double-stranded DNA molecule
2. usually only one
3. extensively looped and coiled
68
What are plasmids?
Small, double stranded DNA molecules that exist independently of the chromosome
69
LIst a few characteristics of plasmids (4).
* extrachromosomal DNA
* found in bacteria, archaea, and some fungi
* usually small, closed circular DNA molecules
* they exist and replicate independently of the chromosome
* episomes- may integrate into chromosome
* inherited during cell division
* contain few genes that are non-essential
* confer selective advandtage to host (e.g., drug resistance)
* classification based on mode of existence, spread, and function
70
What is the function of conjugative plasmids?
transfer DNA from one cell to another
71
What is the function of R plasmids?
carry antibiotic-resistance genes
72
What is the function of Col plasmids?
Produce bacteriocins (substances that destroy closely related species)
73
What is the function of virulence plasmids?
carry virulence genes
74
What are the functions of virulence plasmids?
carry genes for enzymes
75
Does being a gram-negative or gram-positive bacteria allow for extra protection to the cell? Why?
Gram negative because of the presence of the outer membrane
76
What is peptidoglycan (murein)?
it is a component of the bacterial cell wall; a rigid structure that lies just outside of the plasma membrane
77
Gram-positive bacteria stain ______ and have _______ peptidoglycan?
purple, thick
78
Gram-negative bacteria stain \_\_\_\_\_\_\_, have _______ peptidogylcan, and have a(n) ______ \_\_\_\_\_\_\_\_
pink, thin, outer membrane
79
List the functions of the cell wall.
* Maintains shape of the bacterium
* almost all bacteria have one
* Helps protect cell from osmotic lysis
* Helps protect from toxic materials
* May contribute to pathogenicity
80
What is characterisitic of the structure of peptidoglycan?
* it is a meshlike polymer of identical subunits forming long strands
* chains of peptidoglycan subunits are joined by cross-links (covalent bonds) between the peptides
81
What are the two alternating sugars that make up the peptidoglycan polymer structure?
* N- acetylglucosamine (NAG)
* N- N- acetylmuramic acid (NAM)
82
T/F: the peptidoglycan structure in addition the two alternating sugars contain alternating D- and L- amino acids?
True
83
Peptidoglycan strands have a _____ shape?
Helical
84
Some gram-positive cell wall may also contain teichoic acids (negatively charged). What are some of its functions
* help maintian the cell envelope
* protect from environmental substances
* may bind to host cells
85
T/F: gram-psitive bacteria do not have a layer of proteins on the surface of peptidoglycan?
False. some gram-positive bacteria have a layer of proteins on the surface of peptidoglycan
86
List the characterisitics of the periplasmic space of gram-positive bacteria (3).
1. Lies between the plasma membrane and the cell wall and is smaller than that of gram-negative bacteria
2. Periplasm has relatively few proteins
3. enzymes secreted by gram-positive bacteria are called exoenzymes
* aid in degradation of large subunits
87
Which bacterial cell walls are more complex, gram-positive or gram-negative?
gram-negative cell walls
88
These bacterial cell walls consist of a thin layer of peptidoglycan surrounded by an outer membrane?
gram-negative bacteria cell walls
89
Do the cell walls of gram-negative bacteria contain teichoic acids?
no
90
The outer membrane of gram-negative cell walls have three components, what are they?
1. lipids
2. lipoproteins
3. lipopolysaccharide (LPS)
91
In gram-negative bacteria peptidoglycan composes what percentage of the cell wall weight?
~5-10%
92
How does the periplasmic space of gram-negative cell walls differ from that in gram-positive cells?
* may constitue 20-40% of the cell volume
* many enzymes present in the periplasm
* hydrolytic enzymes, transport proteins and other proteins
93
In gram- negative bacteria the outer membrane lies _______ the thin _______ layer?
outside, peptidoglycan
94
These lipoproteins in gram-negative bacteria connect the outer membrane to the peptidoglycan layer?
Braun's lipoproteins
95
LIst three characteristics of lipopolysaccharide (LPS)
1. consists of three parts
* lipid A
* core polysaccharide
* O side chain (O antigen)
2. Lipid A is embedded in the outer membrane
3. core polysaccharide O side chain extends out from the cell
96
Name 4 of 6 reasons why LPS is important.
1. Contribute to negative charge on the cell surface
2. helps to stabilize outer membrane structures
3. may contribute to attachment to surfaces and biofilm formation
4. creates a permeability barrier
5. protection from host defenses (O antigen)
6. can act as an endotoxin (lipid A)
97
Gram-negative outer membrane is ______ permeable than the plasma membrane due to the presence of ______ proteins and ______ proteins?
more, porin, transporter
98
Which type of environments will cause cell lysis?
Hypotonic environments
99
Which types of environments will cause plasmolysis?
hypertonic environments
100
What is plasmolysis?
When the plasma membrane shrinks but the cell wall maintains its shape
101
What type of environment will cause plasmolysis?
Hypertonic environments
102
T/F: the cell wall helps to prevent osmotic lysis?
True
103
Penicillin inhibits ______ synthesis?
Peptidoglycan
104
Name two characteristics of archaeal cell walls
1. They lack peptidoglycan
* some have pseudopeptidoglycan (pseudomurein)
2. the cell wall varies from species to species
105
Define glycocalyx.
* layer consisting of a network of polysaccharides extending from the surface of the cell.
* can include capsules and slime layers
106
List some characteristics regarding capsules (4).
1. usually composed of polysaccharides
2. well organized and not easily removed from the cell
3. visible in light microscope
4. has protective advantages
* resistant to phagocytosis
* protect from dessication
* exclude viruses and detergents
107
List some characteristics regarding slime layers (2)
1. similar to capsules, except diffuse, unorganize, and easily removed
2. slime may aid in motility
108
What is an S Layer?
regularly structured layers of proteins or glycoproteins that self assemble
109
How do the S layers of gram-negative bacteria and gram-positive bacteria differ?
* Gram-negative bacteria the S layer adheres to the outer membrane
* Gram-positive bacteria the S layer is associated with the peptidoglycan surface
110
List some functions of the S layer (5).
1. protect from ion and pH fluctuations, osmotic stress, ezymes, and predation
2. maintains shape and rigidity
3. promotes adhesion to surfaces
4. protects from host defenses
5. potential use in nanotechnology
* S layer spontaneoulsy associates
111
There are external structures that extend beyond the cell envelope in bacteria that function in protection, attachment to surfaces, horizontal gene transfer, and cell movement. What structures participate in the functions?
* Pilli and fimbriae
* flagella
112
List some characteristics of fimbriae (3).
* Short, thin, hairlike, proteinaceous appendages (1000/cell)
* can mediate attachment to surfaces
* some (type IV fimbria) are required for twitchin motility or gliding motility that occurs in some bacteria
113
List some characterisitics of sex pili (3).
* longer, thicker, and less numerous than fimbriae (1-10/cell)
* genes for formation are found on plsmids
* are required for conjugation (mating)
114
What are flagella and what are their functions?
* Flagella are threadlike, locomotor appendages that extend outward from the plasma membrane and cell wall.
* Functions
* motility and swarming behavior
* attachment to surfaces
* may be virulence factors
115
What are the three parts of a flagella?
1. Filament
2. Hook
3. Basal body
116
What are the functions or properties of the three parts of flagella?
1. Filament
* extends from cell surface to the tip
* hollow, rigid cylinder of flagellin protein
2. Hook
* links filament to basal body
3. Basal body
* series of rings that drive flagellar motion
117
LIst the cahracteristics of flagellar synthesis (3).
* complex process involving many genes and gene products
* new flagellin molecules transported through the hollow filament using typ II-like secretion system
* filament subunits self-assemble with the help of filament cap at tip, not base
118
There are 5 different types of flagella distrubition, what are they?
1. monotrichous
2. polar flagellum
3. amphitrichous
4. lophotrichous
5. peritrichous
119
Cells with monotrichous flagella are characterized by?
one flagellum
120
cells that have polar flagellum are characterized by?
flagellum at end of cell
121
Cells with amphitrichous flagella are characterized by?
one flagellum at each end of cell
122
Cells with lophotrichous flagella are characterized by?
cluster of flagella at one or both ends of the cell
123
Cells with peritrichous flagella are characterized by?
flagella spread over the entire surface of the cell
124
Bacteria and archaea can direct their movement several ways. What are some of those ways?
* flagellar movement
* spirochete motility
* twitching motility
* gliding motility
125
What is chemotaxis?
The movement of cells towards attractants such as nutrients, or away from harmful substances
126
This type of bacterial flagellar movement will cause the cell to move foward (run)?
counterclockwise rotation
127
This type of bacterial flagellar movement will cause a disruption in the forward motion (run) and cause the cell to stop and tumble?
Clockwise rotation
128
The flagellum is a 2 part motor producing torque. What are the 2 components?
* Rotor
* C (FliG protein) ring and MS ring turn and interact with strator
* Stator- Mot A and Mot B proteins
* form channel through plasma membrane
* protons move throught Mot A and Mot B channels using the energy of proton motive force
* torque powers rotation of the basal body and filament
129
What are some characteristics of Spirochete motility (3)?
1. Mutliple flagella from axial fibril which winds around the cells
2. flagella remain in peroplasmic space inside outer sheath
3. corkskrew exhibits flexing and spinning movements
130
Twitching and gliding motility may involve ______ \_\_\_\_ _____ and \_\_\_\_\_\_?
type IV pili, slime
131
This type of movement involves short, intermittent, jerky motions?
Twitching
132
This type of movement involves smooth movements?
gliding
133
In the presence of an attractant tumbling frequency is _______ and the frequency of runs in the direction of the attractant is \_\_\_\_\_\_\_?
Decreased, increased
134
T/F: the behavior of bacterium is not altered by temporal concentration of a chemical?
False. the behavior of bacterium IS altered by temporal concentraion of a chemical
135
What is an endospore?
A complex dormant structure fromed by some bacteria (mother cell)
136
The bacterial endospore is resistanrt to numerous environmentla conditions such as?
* heat
* radiation
* chemicals
* desiccation
137
List the components of the stucture of an endospore.
* spore surrounded by this coverin called exosporium
* thick layers of protein form th epsore coat
* cortex, beneath the coat, composed of thick peptidoglycan
* core has nucleoid and ribosomes
138
What are some reasons that endosores are so resistant?
* calcium (complexed with dipicolinic acid)
* small, acid-soluble, DNA-binding proteins (SASPs)
* dehydrated core
* Spore coat and exosporium provide protection
* DNA repair enzymes
139
What is sporulation?
The process of endospore formation
140
When does sporulation occur?
Normally commences when growth ceases due to a lack of nutrients
