Chp 4 prokaryotic diversity Flashcards
What are the main shapes of prokaryotic cells?
Coccus (spherical), Bacillus (rod-shaped), Vibrio (curved rod), Spirillum (stiff spiral), Spirochete (flexible spiral), Coccobacillus (intermediate between coccus and bacillus), and Pleomorphic (variable shape).
What is the difference between spirillum and spirochete?
Spirillum is a stiff, spiral-shaped bacterium, while spirochete is a flexible, spiral-shaped bacterium.
What is a coccobacillus?
A shape that is intermediate between spherical (coccus) and rod-shaped (bacillus).
Define pleomorphic bacteria.
Bacteria that vary in shape and size.
What are curved rod-shaped bacteria called?
Vibrio.
What bacterial shape is spherical?
Coccus.
What bacterial shape is rod-like?
Bacillus.
What shape do bacteria with rigid spirals have?
Spirillum.
What bacterial morphology involves flexible spirals?
Spirochete.
What term describes bacteria with variable shapes?
Pleomorphic.
What are the three main methods of prokaryotic reproduction?
Binary fission, snapping division, and budding.
What is the most common form of reproduction in prokaryotes?
Binary fission.
What is binary fission?
A form of asexual reproduction where a single cell divides into two identical daughter cells.
Describe the steps of binary fission.
- Chromosome replication 2. Cell elongation 3. Septum formation 4. Cell division 5. Repeat process.
What is snapping division?
A type of binary fission where only the inner portion of the cell wall is synthesized, causing the outer wall to snap.
What bacterial arrangement results from snapping division?
V-shapes and palisades.
What is budding in prokaryotes?
An asymmetric form of cell division where a new cell grows from the parent cell as a bud.
What type of prokaryotes reproduce by budding?
Some Gram-negative bacteria like Planctomycetes.
How does the chromosome replicate in binary fission?
It attaches to the cytoplasmic membrane and replicates before cell elongation.
How does snapping division differ from binary fission?
Only the inner cell wall is synthesized, leading to a snap-like break of the outer wall.
What structural feature forms during budding?
A stalk for attachment.
What is a common outcome if cells remain attached after binary fission?
They form chains.
What are the five types of prokaryotic symbiotic relationships?
Mutualism, commensalism, parasitism, amensalism, and neutralism.
Define mutualism and provide an example.
Both organisms benefit; e.g., gut microbiota providing vitamins to humans.
Define commensalism and provide an example.
One organism benefits while the other is unaffected; e.g., Staphylococcus epidermidis on human skin.
Define parasitism and provide an example.
One organism benefits while harming the other; e.g., pathogenic bacteria infecting a host.
Define amensalism and provide an example.
One organism is harmed while the other is unaffected; e.g., antibiotic-producing fungi killing nearby bacteria.
Define neutralism and provide an example.
Both organisms are unaffected; e.g., dormant endospores next to active bacteria.
What is symbiosis?
Close, long-term interaction between two different species.
What type of relationship do methanogens have in a cow’s gut?
Mutualism; methanogens help reduce acidity and receive nutrients.
How do bacteria contribute to cow digestion?
They break down cellulose into simple sugars for fermentation.
What is microbial ecology?
The study of relationships between microorganisms and their environments.
Name three structural differences between archaea and bacteria.
Archaea lack peptidoglycan, have ether-linked lipids, and unique attachment structures like hami.
What is the main structural difference in cell walls between archaea and bacteria?
Archaea lack peptidoglycan, some have pseudomurein, lipid monolayers rather than bilayers, cytoplasmic mem lipids can be branched or ring form rather than straight chains.
How do archaeal membranes differ from bacterial membranes?
Archaea have ether-linked lipids, while bacteria have ester-linked lipids.
What unique structure do some archaea use for attachment?
Hami (grappling-hook-like appendages).
How do archaeal flagella (archaella) differ from bacterial flagella?
Archaella are powered by ATP hydrolysis, not proton motive force.
What type of genetic material do both archaea and bacteria have?
Circular chromosomes.
Do archaea or bacteria have histones?
Archaea have histones; bacteria do not.
What is the starting amino acid for protein synthesis in archaea?
Methionine (like eukaryotes).
Which domain of life can produce methane?
Archaea (methanogens).
Are archaea or bacteria more likely to live in extreme environments?
Archaea (extremophiles).
What are two types of archaeal cell walls?
S-layer (protein shell) and pseudomurein.
What makes archaeal membranes stronger in extreme environments?
Lipid monolayers (ether linkage)) and branched tails (phytanyl).
What are methanogens?
Archaea that produce methane by reducing CO2 or organic acids.
Where are methanogens commonly found?
Cow guts, wetlands, and ocean sediments.
What are extremophiles?
Organisms that thrive in extreme environments.
What are halophiles?
Archaea that require high salt concentrations.
What are thermophiles?
Archaea that thrive at temperatures above 45°C (DNA, RNA, cytoplasmic membranes, and proteins do not function properly below 45°C). Hyperthermophiles need temp.s over 80°C.
What is the temperature range for hyperthermophiles?
Above 80°C.
What archaeal genera are hyperthermophiles?
Thermococcus (60°C and 80°C in hydrothermal vents) and Pyrodictium (80°C and 105°C in deep sea thermal vents).
What is chemosynthesis?
Using inorganic molecules to produce organic compounds.
How do archaea survive in hydrothermal vents?
By using chemosynthesis of sulfur-rich compounds.
What structural adaptation helps halophiles balance osmotic pressure?
Osmoprotectants (small organic molecules with a neutral charge & low toxicity). Ramp up concentration of things like
amino acids and sugars in their cytoplasm to help balance high salt concentration outside of cells.
