Chapter 27 Flashcards
the most common organisms on earth are ___. They are divided into 2 domains which are ___ and ___.
most are very ___ and have a ___.
- prokaryotes
- bacteria, archaea
- small, cell wall
most bacteria have cell walls of ___, which consists of sugars and proteins
peptidoglycan
gram-positive bacteria ___
take violet/purple colored stain
gram-negative bacteria ___
the violet stain washes out of these (pink)
-these bacteria have an outer membrane covering the cell wall
___ pathogenic bacteria are more dangerous than ___ bacteria.
- gram-negative
- gram-positive
___ pathogens often have toxins in their outer membrane and are more resistant to antibiotics than are ___ pathogens.
- gram-negative
- gram-positive
many prokaryotes have a sticky protective coating called a ___
capsule
- cocci (coccus):
- bacilli (bacillus):
- spirochetes and spirilla:
- vibrio:
- spherical shaped
- rod shaped
- helical, corkscrew shaped
- comma shaped
cocci occurring in pairs
diplococci
cocci occurring in chains
streptococci
cocci occurring in clusters
staphylococci
filament shaped and used for locomotion
flagella
rigid cylindrical rods used to anchor prokaryotes to food sources and for conjugation
pili
shorter and more numerous than pili
fimbriae
the genome (the genes) of prokaryotes, on average, have ___ as much DNA as eukaryotes.
one thousandth
the genome of a prokaryote is in the form of a ___, the eukaryote genome is ___.
- ring
- linear
prokaryotes reproduce through ___, a form of cell division
binary fission
binary fission is a type of ___
asexual reproduction
3 forms of prokaryote genetic recombination:
- transformation
- transduction
- conjugation
taking up genes from their surroundings
transformation
transfer of genes between prokaryotes by viruses
transduction
transfer of genes from one prokaryote to another. small rings of DNA called plasmids are transferred during this.
conjugation
some prokaryotes can form into very tough ___ that can allow them to withstand extreme conditions.
endospores
___ are food-filled cells produce by some cyanobacteria. they can withstand stressful conditions such as cold weather.
akinetes
use light as energy
phototrophs
obtain energy from chemicals in their environment
chemotrophs
require only CO2 as a carbon source
autotrophs
require organic molecules as a carbon source
heterotrophs
- use light as an energy source and CO2 as a carbon source
- prokaryotes
- eukaryotes
- photoautotrophs
- cyanobacteria
- plants and algae
use inorganic chemicals as an energy source and CO2 as a source of carbon
-certain prokaryotes only
chemoautotrophs
use light as an energy source and organic molecules as a carbon source
-certain prokaryotes only
photoheterotrophs
use organic molecules as energy source and a source of carbon
- many prokaryotes
- many eukaryotes including animals, fungi, many protists, and a few plants
chemoheterotrophs
obligate aerobes:
facultative anaerobes:
obligate anaerobes:
- require oxygen
- will use oxygen if available but can live without oxygen
- can not live with oxygen present
the ___ tend to inhabit extreme environments, although non-extreme forms have now been found
archaea
most named prokaryotes are ___
bacteria
the three main groups of extremophile archaea are:
methanogens, extreme halophiles, and extreme thermophiles
live in anaerobic conditions such as in marshes and garbage dumps. produce methane
methanogens
live in very salty places
extreme halophiles
live under very high temperatures
extreme thermophiles
many prokaryotes are ___, they live in direct contact with other species. The larger of the two species is called the ___.
symbiotic
host
3 forms of symbiosis:
mutualism, commensalism, and parasitism
both symbionts benefit
mutualism
one symbiont benefits, the other symbiont is neither helped nor harmed
commensalism
the parasite benefits, the host is harmed
parasitism
there would be no other life without prokaryotes. they are very important for ___.
-cycling nutrients through the ecosystem
the prokaryotes are important ___, they can break down organic materials in dead organisms
decomposers
certain species of bacteria can “fix” atmospheric nitrogen into a form that can be used by other organisms
nitrogen fixation
consist of a nucleic acid (DNA or RNA) covered with a coat of protein. they take over a host cell and force the cell to make copies until the host cell bursts open releasing new viruses
virus
viruses that infect bacteria
bacteriophages
tiny strands or circles of RNA with no protein coat
-cause plant diseases
viroids
an alternate form of a protein that can change unaltered forms of the protein in the nervous system of animals -fatal
prions
___ in humans are caused by prions
___ in sheep
- Kuru and Creutzfeld-Jakob disease (CJD)
- Scrapie
- Bovine spongiform encephalopathy (BSE) “Mad Cow Disease”
- BSE and CJD are probably linked
