Ch. 25 Bacteria And Archaea Flashcards
Almost all prokaryotes have walls that hold them into one of three basic forms:
- Rods (bacilli)
- spheres (cocci)
- long coils (spirilla)
- protoplasm
Bacteria and archaeans are almost invariably unicellular and never have __ or __
Tissues or organs
There is no nuclear envelope; instead, DNA occurs as one or several masses called ___ within the cytoplasm
Nucleoids
DNA is in the form of ___
Closed circles
They have __ ribosomes
70S
In gram-Positive cells, the cell wall consists of a thick layer of a polymer called ___
Peptidoglycan
In gram-negative bacteria, the peptidoglycan layer is present but thin, and a layer of ____ lies exterior to it
Lipopolysaccharide (LPS)
Many bacteria have flagella, composed of just one type of protein, ___
Flagellin
Cell division occurs by ____
Binary fission
Binary fission
Cell simply pinches in two
___ occurs when some bacteria die and their DNA breaks into rather large pieces, each with one or several genes
Transformation
___ is similar to transformation but occurs when a virus invades a cell and reproduces
Transduction
___ involves specific structures and metabolisms that are the result of natural selection favoring genetic exchange
Conjugation
Prokaryotes have numerous alternate methods for metabolic processes:
Several types of photosynthesis, multiple types of respiration, and numerous sources of energy other than sunlight or sugars exist
Prokaryotes are almost all ___, so they have very little anatomy and virtually no morphology
Unicellular
Their systematics and classification have been based almost entirely in their..
- metabolism
- wall chemistry
- ability to carry out photosynthesis and use various substrates
- sensitivity to oxygen
___ is now the most powerful and reliable technique for analyzing prokaryote evolution
Nucleotide sequencing
Archaeans are distinct ___, but they remember other prokaryotes ___
Metabolically; structurally
Archaean cell walls contain ___, ___, or ___, but they lack a true peptidoglycan component
Protein, glycoprotein, or polysaccharide
The overall metabolism of archaeans is exotic in that most thrive in certain ___ environments
Rare
Domain ____ contains many more species than does domain archaea
Bacteria
Gliding bacteria
Move only when in contact with a solid surface; they have no flagella
Cytophaga
- gliding bacteria
- digest celluloid and chitin
Nitrogen-metabolizing becteria
Affect the amount of nitrogen available to all other life forms
Nitrogen-fixing bacteria
Convert atmospheric N2 into nitrites, nitrates, and ammonium
Nitrifying bacteria
Oxidize ammonia in the environment to nitrate or nitrite
Denitrifying bacteria
Convert nitrogen compounds to N2 gas
Mycoplasma
Bacteria that completely lack a cell wall
- many are pathogenic
Until the 1970s, Cyanobacteria were thought to be closely related to true algae and were called ___
Blue-green algae
The walls of Cyanobacteria are like those of other gram-negative bacteria, but they also produce an..
Extra layer of mucilage that binds cells and filaments together into a small, loose aggregation
Cyanobacteria are of special interest because they seem to be most closely related to the organisms that might have given rise to ___
Chloroplasts
The ability of Cyanobacteria to ___ is important ecologically because these are widespread and often more active than other nitrogen-fixing bacteria
Fix nitrogen
Cyanobacteria inhabit numerous extremely harsh environments, withstanding intense ___ and periods of almost complete ___
Insolation; desiccation
Stromatolites
When Cyanobacterial growths become gigantic and so heavily encrusted with calcium carbonate that they appear to be stones
Prokaryotes are composed of three groups:
Bacteria, Cyanobacteria, and archaebacteria
