Lecture 2- Bacterial cell structure Flashcards
In regards to shape most bacteria can be termed?
Monomorphic
T/F: Most bacteria are pleomorphic?
False, most bacteria are monomorphic
Define pleomorphic.
Being variable in shape and lacking a single, characteristic form
These are responsible for the characteristics of bacteria size and shape.
Genes
T/F: As bacteria age they can change shape?
True
List the 3 basic shapes of bacteria.
- bacillus
- coccus
- spiral
Name the 3 subtypes of spiral shaped bacteria.
- spirillum
- vibrio
- spirochete
These spiral shaped bacteria can have one or more twists.
Spirillum
These spiral shaped bacteria look like like a curved rod
Vibrio
These spiral shaped bacteria are flexible, helical spirals.
Spirochete
List two shape types that are unusual for prokaryotes.
- Star-shaped bacteria
- rectangular bacteria
Bacteria shape arrangement can fall under 3 categories, what are they?
- Pairs
- Clusters
- Chains
Pairs of cocci or bacilli would be called what, respectively?
Diplococci and diplobacilli
Clusters of cocci would be called what?
Staphylococci
Chains of cocci or bacilli would be called what, respectively?
Streptococci and streptobacilli
Diplococci, streptococci, diplobacilli, and streptobacilli bacteria have how many planes of division?
1
Tetrad bacteria have how many planes of divisions?
2
Sarcinae bacteria have how many planes of divisions?
3
What are branched networks of long mulitnucleate filaments?
Mycelium
Do smaller or larger bacteria cells have a greater surface area to volulme ratio?
Smaller cells have greater surface area to volume ratio
What is the benefit for bacteria being smaller rather than larger?
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.
Does cell shape affect the Surface area to volume ratio?
Yes
Comparing a rod with a coccus of the same volume, which will have a greater nutrient flux across its plasma membrane?
The rod because it will have a greater surface area to volume ratio than the coccus
Name some functions of the bacterial pplasma membrane.
- 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
What is the function of a bacterial gas vacuole?
An inclusion that provides buoyancy for floating in aquatic environments
What is the function of bacterial ribosomes?
Protein synthesis
What are the functions of bacterial inclusions?
Storage of carbon, phosphate, and other substances
What is the function of the bacterial nucleoid?
localization of gentic material (DNA)
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
What is the function the bacterial cell wall?
- protection from osmotic stress
- helps maintain cell shape
What are the functions of bacterial capsules and slime layers?
- Resistance tophagocytosis
- adherence to surfaces
What are the functions of bacterial fimbriae and pili?
- Attachment to surfaces
- bacterial conjugastion and transformation
- twitching and gliding motility
What are the functions of bacterial flagella?
swimming and swarming motility
What is the function of the bacterial endospore?
survival under harsh conditions
Name the 3 components of the bacterial cell envelope.
- plasma membrane
- cell wall
- layers outside the wall (capsule or slime layer)
This structure is a must have for all living organisms.
plasma membrane
T/F: All bacteria have internal membrane systems?
False, some do
T/F: Bacterial membranes are similar to eukaryotic membranes in that they are lipid bilayers and many of their amphipathic lipids are phospholipids
True
Bacterial membranes usually differ from eukaryotic membranes in lacking sterols (steroid-containing lipids). Instead they contain steroid-like molecules called what?
hopanoids
What are the functions of the hopanoids in the bacterial membranes?
They help to stabilize the membrane
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
Name two ways that archaeal membranes are different from bacterial and eukaryotic membranes.
- They are composed of lipids that differ chemically from those of bacteria and ukaryotes
- Some have a monolayer structurs intead of a bilayer structure
List 2 defining characteristics of bacterial or eukaryotic membrane lipids.
- contain ester bonds
- have 2 hydrocarbons attached to a glycerol
List 3 defining characteristics of archaeal membrane lipids.
- contain ether bonds
- contain branched molecules
- some are contain tetraethers
List 3 plasma membrnae functions.
- It encompasses the cytoplasm
- acts as a selectively permeable barrier
- interacts with the external environment
- receptors for detection of and response to chemicals in surroundings
- transport systems
- metabolic processes
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
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
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
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
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
Plasma membrane infoldings would be observed in bacteria perfoming what types of functions?
- many photosynthetic bacteria
- many bacteria with high repiratory activity
What is an anammoxosome and what is its function in Plantomycetes?
It is an organelle. It is the site of anearobic ammonia oxidation
What are inclusions?
granules of organic or inorganic material that are stockpiled by the cell for future use
What are the functions of storage inclusions?
storage of nutrients, metabolic end products, energy, and building blocks
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
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