Chapter 3 Flashcards
What does prokaryote mean and what are characteristic of them?
- prenucleus
- contain: plasma membrane, cell wall, flagella/cilia, DNA, ribosomes, NO Organelles
What does eukaryote mean and what characteristics represent this group?
- true nucleus
- contain: plasma membrane, cell wall in plants, no cell wall in animals, flagella/cilia, DNA that is self contained, organelles ribosomes.
What are the basic shapes of prokaryotes?
- bacillus (rod)
- coccus (spherical)
- spiral
Can spiral shape of prokaryotes be described in more detail? If so, what are they?
- spirillum (one or more twists)
- vibrio (curved rod) one bend, look like banana
- spirochete (flexible, helical spirals)
Describe what a stella bacteria looks like.
star shaped and is prokaryotic
There are multiple ways to arrange bacteria, what are three common, simple methods?
pair: complete binary fission with incomplete separation
- clusters
- chains
What does the prefix diplo- describe?
pairing of bacteria
What does staphylo describe?
clustering of bacteria
What does strepto describe?
chains of bacteria
Diplo and strepto- divide in how many planes?
1
Sarcinae describes what type of division of bacteria?
into 8ths, with 3 planes of division
What is the benefit of being a smaller cell?
there is a larger surface area to volume ratio, due to infoldings on the PM
Bacterial membranes do not contain sterols. With this in mind what do they use to stabilize their membrane?
without the presence of sterols (cholesterol) bacterial membranes contain hopanoids
-hopanoid: sterol-like in nature
Where can high amounts of hopanoid be found?
and what does a hopanoid do?
largely found in petroleum
True/False
Bacteria and Eukaryotes have significantly different lipids systems and therefore plasma membranes.
False.
Bacteria and eukaryotes are similar and both differ from the archaea
What do archaeal lipids contain that eukaryotic/bacterial lipids do not?
- ether bonds and not ester bonds.
- branched molecules
- hydrophilic section: is polysaccharide not phosphate group
What components in eukaryotic cytoskeletal is also seen in bacteria?
- actin/microfilaments
- intermediate filaments
- microtubules
FtsZ is a bacterial cytoskeletal protein. What is its function and where can it be largely found?
- forms ring during septum formation during cell division
- large diversity in bacteria and archaea
MreB has what function?
- bacterial cytoskeletal protein found in BACILLI, not in cocci.
- maintains shape by manipulating peptidoglycan synthesis machinery
CreS is a bacterial cytoskeletal protein. What does it do and where is it found?
helpls maintain a curve shape.
- most likely found within bacteria -vibrio
What is a storage inclusion?
-granules of organic or inorganic material that will use the stores in the future
What is generally stored in storage inclusions?
- nutrients, metabolic product, energy, building components
- glycogen
- carbons
- phosphate
- amino acids
- sulfur granules
A magnetosome can be categorized as what?
- storage inclusion
- uses the earth magnetic field to properly orient aquatic bacteria
Where is Rubisco contained?
-contained in a microcompartment (carboxysome)
What is the function of the carboxysome?
-fix carbon dioxide to bacteria with the help of enzyme rubisco
The svedburg unit is a measure of what?
- how quickly a particle will sediment in centrifuge.
- The larger the number, the longer it takes for the particle to sediment and therefore the larger the particle.
What are characteristic features of the nucleoid?
- not membrane bound
- contains chromosomes and associated proteins
- 1 closed circular double-stranded DNA molecule
- participate in folding by supercoiling DNA
1 circular double stranded DNA molecule is generally characteristic of what?
prokaryotic chromosome
What is a plasmid?
extrachromosomal DNA in bacteria, archaea and fungi
-it is classified based on mode of existence, spread, and function
What is the function of a plasmid?
contains and helps transfer non-essential genes, but may help improve survival (AB resistant)
-also exist and replicate independent of chromosomes
Describe the major difference between gram positive and gram negative bacteria.
- gram positive have thick peptidoglycan (cell wall) and thin PM
- gram negative have PM, thin peptidoglycan layer, periplasmic space, and outer membrane layer.
What is the purpose of peptidoglycan layer?
- maintains bacterium shape
- prevents osmotic lysis (when would this occur?)
- protect against toxins
- contributes to pathogenicity
How does the peptidoglycan layer contribute to pathogenicity?
- this layer covers the ‘flags’ presented on the PM that Ab can use to distinguish as hostile or not.
- covering the flag makes the bacterium somewhat invisible to the Abs
What are the components of the peptidoglycan layer?
-alternating strands of NAM, NAGs and an alternating pattern of D- L- amino acids.
What is a common cross-linkage in the peptidoglycan layer of gram negative cells?
cross link between D- Ala and DAP
What is the common cross linkage of the peptidoglycan layer of gram positive cells?
D-Ala to L-Lys with a Gly interbridge
Why do gram positive cells contain teichoic acid, when gram negative do not?
the thicker peptidoglycan layer requires extra support in order to maintain the cell envelope.
Act like rebar that extend down to the PM surface
What are the functions of the teichoic acids?
- negatively charged
- maintain cell envelope
- protect against environmental factors
- can bind to host cells
Do gram positive bacteria secrete any type of enzymes?
-exoenzymes that work to degrade large nutrients
What is the outer membrane composed of ans where is it located?
- lipids, lipoproteins, lipopolysaccharides
- thin layer that surrounds the peptidoglycan and PM layers of gram negative bacterium
Why are lipopolysaccharides important to bacterium?
- form negative surface charge
- stabilize outer membrane
- attach to surfaces or form biofilm
- protects against O Ag
- acts as endotoxin (lipid A)
Is the outer membrane more or less permeable when compared to the PM?
- more permeable because it contains porin proteins and multiple transporter proteins that can aid in facilitated diffusion
Describe the difference between lysis and plamolysis.
- lysis occurs in a hypotonic environment as fluid will fill the cell and cause it to burst
- plasmalysis occurs in a hypertonic environment as water will leave the cell. resulting in the cell wall to maintain structure while the PM will shrink in size
What breaks the bond between NAG and NAMs?
lysozymes, which contribute to the lysis of the cell.
Which cell types are more susceptible to lysozymes?
-Gram positive lack the thin outer membrane and peptidoglycan layer will be more rapidly attacked.
What effects does penicillin have on bacterium?
- inhibition of the peptidoglycan synthesis
- -reduces the layers that lysozome must penetrate in order to lyse the cell.
What is significant about pseudopeptidoglycan?
- specific to arachaea in that it will differ in chemical structure when compared to peptidoglycan
- is similar to eukaryotic in terms of function, mrphology, and physical structure
Lysozomes are useful in degrading peptidoglycan becasue it has an beta-1, 4-glycosidic linkage. Are lysozomes useful against pseudopeptidoglycans?
-No, pseudopeptidoglycans contain Beta-1, 3-glycosidic linkages and are therefore not affected by lysozomes.
What is contained outside the cell wall?
- outermost layer of cellular envelope
- glycocalyx: capsules, slime layer, S layers
- biofilms that attach to solid surfaces
What is the component of a capsule and how does it benefit the bacterium?
- composed of polysaccharides
- protects against desiccation and phagocytosis
What is a slime layer?
- similar to a capsule but is more diffuse and unorganized.
- will aid in motility and not adhesion
What is an S layer and the differences between the gram positive and gram negative attachment sites?
- a self assembling layer of protein or glycoproteins.
- gram (-) attach to the outer membrane
- gram (+) attach to the peptidoglycan surface
A bacterium is able to maintain its shape, adhere to surfaces, protect itself from host defense, and protects itself from environmental dangers. What is present that allows a bacterium to do so?
- S layer
Fimbriae can do what?
- mediate attachment to surfaces
- - type IV used in twitching or gliding motility
What is the purpose of a sex pili?
allows for the exchange of plasmids and other DNA material during conjugation with other bacterium
What are the three parts of flagella in bacteria?
- filament: extends from cell surface to tip and is a hollwo rigid cylinder
- Hook: links the filament to the basal body
- Basal Body: the series of rings, attached to the different membrane layers that act as the motor unit
Monotrichous
Amphitrichous
- one flagellum
- one flagellum at each end
Polar flagellum
-flagellum at end of cell
Lophotrichous
cluster of flagella at one or both ends of cell
Peritrichous
flagellum spread over the entire surface
What are the different types of directed movement that is seen in bacteria and archaea?
- flagellar: best in liquid
- spirochete: corkscrewing best used in viscous liquid
- twitching/gliding: best used on hard surface, flagella not likely to be present
What is chemotaxis?
movement toward chemical attractants and away from harmful substances
What will cause a bacterium/cell to move, via chemotaxis?
- temperature change
- light
- oxygen
- osmotic pressure
- gravity
In what direction do most flagella rotate in order to produce a forward movement? A tumbling type movement?
- counterclockwise
- clockwise
How does the flagella rotate and produce movement?
- proton gradient flows from periplasmic space into the cytoplasm between MotA and MotB
True/ False
The twitching and gliding motility is used on solid surfaces, and could potentially require help from type IV pili and S layers.
False.
twitching and gliding can have help from type IV pili and slime
What is the best way to describe a bacterial endospore?
- this complex, dormant structure is formed by some bacteria, when growth conditions are not optimal.
Is the bacterial endospore very hardy?
-yes, it is able to resist heat, radiation, chemicals, and desiccation and is formed within the mother cell.
Is endospore formation considered to be replication?
no, one bacterium is being conserved and then one bacterium is being released
Why is the endospore so resistant to a variety of environmental factors?
Presence of:
- calcium
- small acid soluble DNA binding proteins
- dehydrated core
- DNA repair enzymes
- spore coat.
Sporulation
- endospore formation of up to 10 hours.
- begins when nutrients dwindle
- incorporate keratin to improve resistance of the spore coat over time.
