lecture 2&3 Flashcards
what does Cooci look like? Bacilli? Vibros, spirilla, spirochetes, and pleomorphic?
Vibrios - curved/comma shaped
Spirilla - rigid spiral-shaped
Spirochetes - flexible spiral-shaped
Pleomorphic - organisms that are variable in shape
Cocci - single or arranged spheres
Bacilli - rods
what is the purpose of the different shapes of bacteria?
protective mechanisms or aid infection
what are three common bacterial features, and what does each do?
- Cell envelope - plasma membrane and surrounding layers external to it
- plasma membrane - innermost and selectively permeable membrane and interacts with external environment
- cell wall - maintain shapes, protects cells from toxic materials and osmotic lysis
Bacterial lipids:
- The plasma membrane - made up of amphipathic lipids
- Hopaniods - hydrophobic molecules similar to cholesterol (impacts fluidity and shape and forms functional microdomains for protein assembly)
what does the cross-linking mean for peptidoglycan and what are the two types?
- what does it alternate?
- The stands have a helical shape and are crosslinked for strength
- Direct cross-link - between amino and carboxyl groups
- Indirect cross link - peptide interbridge may form
- NAG and NAM - alternating sugars
what color does gram-positive stain?
- what kind of membrane?
- peptidoglycan?
- may contain?
- purple
- primarily composed of peptidoglycan
- has teichoic acids
- periplasm (between the plasma membrane and cell wall) and a few proteins
what are teichoic acids?
- negatively charged
- These make sure to maintain the cell envelope
- Protect from environmental substances
- May bind to host cells to initiate infection
gram negative
- stain?
- peptidoglycan?
- OM?
- pink or red
- thin layer of peptidoglycan surrounded by an outer-membrane composed of lipids, lipoproteins and lipopolysaccharides
- no teichoic acids
- outer membrane outside thin peptidoglycan, connected to peptidoglycan by brauns liporprotins
LPS - lipospolysaccarides
- contribute to a negative charge on the surface
- Helps stabilize the outer membrane
- Host defense protection
- Acts as endotoxin
what are the the component that make the ooutside of the cell wall?
capsules
slime layers
S layer
bacterial cytoplasm
what are capsules?
- like a jacket
- Are well organized and cannot be easily removed from the cell
- Usually composed of polysaccharides
- Protective function - resistant to phagocytosis, protects from desiccation, and excludes viruses and detergent
what are slime layers?
- Similar to capsules but they diffuse, unorganised, and easily removed
- May facilitate motility
- Cheap version (like vasleine instead of jacket)
S (surface layer)
- Regularly structures self-assembling layers of protein or glycoprotein
- Protect from ion/pH fluctuations, osmotic stress, enzymes, predation, host defense - these are only in cells with extreme environments
- Maintains shape and rigidity
- Promotes adhesion to surface
intracytoplasmic membranes
- plasma membrane in-foldings
- observed in photosynthetic bacteria and high respiratory activity
bacterial cytoskelton
- Protein filaments that participate in cell division, localize proteins, and maintain cell shape
gas vacuoles
Involved in bacterial movement
Provide buoyancy to aquatic bacteria
Made of aggregates of hollow, cylindrical gas vesicles
ribsomes?
Complex protein/RNA structure that have Sites of protein synthesis ( 70s)
Nucleoid
Usually not membrane-bound
- Usually 1 closed circular ds DNA molecule/chromosome
- supercoiling and nucliode proteins aid in folding and structures
plasmid
Small, closed, circular, independent DNA molecules
Carry genes that can confer a selective advantage in some situations
what are the three external structures? purpose?
- fuction in protection, attachment to surfaces , HGT, cell movement
- fimbriae/pili
- sex pilli
- flagella
what are fimbira/pili?
Short thin hair-like, protein appendages
Can mediate attachment to surfaces, motility, and DNA uptake
sex pili?
Longer, thicker, less numerous
Required for conjugation
More defined hollow and produces genetic variation
Flagella
function and what it looks like?
- Threadlike, locomotor appendage extending outward from the plasma membrane and cell wall
- motility, attachment to surface, virulence factor (causes disease)
what are the three parts of the bacterial flagella?
1.) filament /flagellum - extends from cell surface to top
2.) Hook - short flexible segment
3.) Basal body - embedded in cell envelope
what is the two-part motor-producing technique?
- Rotor - moving parts, C-ring ring interact with stators and connects to the rod
- Stator- stationary parts, capture PMF through the membrane to generate torque and drive rotation
what are two ways that flagella can move?
- rotates like a propeller
CCW rotation = forward movement
CW disrupts run = tumble
how can flagella move?
- chemotaxis: movement towards a chemical attraction or away from chemical repellant
- Chemoreceptors transmit signals throughout the chemosensing system - detect external signals and determine whether it should run or tumble
swarming ?
- long collective run togetehr (lot together)
- Cells move faster than swimmers and have increased resistance to antibiotics
what are the three ways that a bacteria will move without using a flagella?
1.) twitching - short, jerky movement (cells are in contact with each other and surface)
2.) gliding - smooth movement w/o appendage and slime can help with movement
3.) spirochete motility - flagella is on the inside and windling around cell (flexing and spinning movement)
what is a survival stratgey made by a bacteria?
- using endospores in response to nutrient depletion
- which are resistant to envionrmnetal changes
how does archaea cell envelope differ from bacteria?
- some lack cell walls
- The slime layer is used to mediate cell-to-cell interactions
- s-layer is standard used
The common shape of archaea?
-cocci and rod shape
what does an archaea membrane look like?
- unique lipids - that are branched chains of hydrocarbons attached to a glycerol by ether linkage
what is the difference between archea and bacterias cytoplasm?
- A ribosomes have different nuc sequences so which means the protein composition is different (makes them unaffected by antibiotics attacking ribosomes)
- more similar to Euk
what are the two types of pilli? archaea
- cannulae - hollow tube structure (how daughter cells are connected to each other)
- hami - looks like a grappling hook (biofilm)
three characteristics of Archaea flagella?
- thinner than bacteria - not hollow
- powered by ATP hydrolysis
- direction moves the cell forward or backward
what is EUK plasma membrane made up of?
sphingolipids
sterols
phospholipids (hydrophobic fatty acids)
Two types of euk? charachteristics?
- protist and fungi
- common in ecosystems
- adapts
- larger than A and B
- major human pathogen
EUK
cytoskeleton (3 types of filaments)
- helps organize cytoplasm
- cell shape/motor proteins associated with filaments that guide cell movements
1. actin - small (helps shape)
2. microtubules - thin (spindles)
3. intermediate - flexible and structural
EUK flagella and cillia
- long whiplike and move in an undulating fashion
- short hair-like structures and beat with 2 phases
viron?
nucleocapsid
- mature virus particles
- composed of nucleic acid (DNA or RNA) and a protein coat (capsid)
2 broad types of virus?
- non-evloped (naked)
- enveloped - has a lipid membrane
viral envelope?
- a flexible membraneous layer of lipids and carbs
- can have spikes or peplomers on their surface
- can be used to identify a virus
what are the five steps of viral multiplcation?
1.) attachment
2.) entry
3.) synthesis
4.) assembly
5.) viron release
how does a virus attach and enter?
- ligand attaches to host cell receptor (determines host prefrence)
- virus genome enters
three methods used to release DNA?
- fusion of biral envelope with host cells plasma membrane
- endocytosis
- release of nucleic acid
what are the two ways virons can be released?
- host cell lysis (non-enveloped)
- relase by budding (enveloped)
virulent phage vs temperate phage
- v - has one reproductive choice (multiplies upon entering and released from host by lyses)
- T - two reproductive options (reproduces lytically like virulent and will remain in host cell without destroying it)
lysogeny
- relationship between temperate phage and host
- prophage form of the virus that remains within host until unfavorable conditions and will convert into lytic where it will burst out of cell
how can viruses by cultivated?
- viruses can not be cultured
- plaque-forming units (lytic cycle)
one step growth curves
1.) inoculation - virus binds (decrease)
2.) Eclipse - virion penetrates cells (plateau)
3.) Burst - host cell releases many viral particles (increase)
4.) Burst size - number of virions released per bacterium (plateau)
