27 Flashcards
Gram -
thin peptidoglycan layer and outer
membrane
structurally more complex
Gram +
thick peptidoglycan layer
stains violet
Three factors contribute genetic diversity:
- Rapid reproduction
- Mutation
- Genetic recombination
Extremophile
an organisms that grows in extreme conditions or habitats
what is peptidoglycan
most bacterial cell walls contain this.
a polymer composed of modified sugars cross linked by short polypeptides
is gram + or gram - more resistant to antibiotics?
gram negative is more resistant to antibiotics because the outer membrane impedes entry of drugs
capsule
cell wall of many prokaryotes is surrounded by a sticky polysaccharide or protein layer, which is a capsule
nucleoid
prokaryotes lack a nucleus. their chromosomes are located in the nucleoid which is a region of cytoplasm that is not enclosed by a membrane
bacteriophages
viruses that infect bacteria
extremophiles
“lovers” of extreme conditions. includes extreme halophiles and thermophiles
first prokaryotes assigned to domain archaea live in extreme environments
extreme halophiles
live in highly saline environments such as the the great salt lake
extreme thermophiles
thrive in very hot environments such as hot water in Yellowstone
decomposers
break down dead organisms
symbiosis
an ecological relationship in which two species live in close contact with each other
parasite
eats cells contents, tissues, or body fluids of its host
pathogen
parasites that cause disease are pathogens, many of which are prokaryotic
key features of prokaryotic reproduction
reproduce via binary fission, short generation times, and can divide every 1 to 3 hours
transformation
a change in genotype and phenotype due to the assimilation of external DNA by a cell
genetic recombination
the recipient cell’s chromosome becomes a combo of DNA derived from 2 cells
conjugation
DNA is transferred between 2 prokaryotic cells that are temporarily joined
nitrogen metabolism
Prokaryotes can metabolize nitrogen in a wide variety of forms (including N2)
example: cyanobacteria
nitrogen fixation
convert atmospheric nitrogen to ammonia (NH3)
metabolic cooperation
metabolic cooperation between different prokaryotic species often occurs between surface coating colonies known as biofilms
obligate aerobes
must use O2 for cellular respiration and can’t grow without it
obligate anaerobes
are poisoned by O2
anaerobic respiration
substances other than O2 such as nitrate ions and sulfate ions accept electrons at the downhill end of electron transport chain
facultative anaerobes
use O2 if it is present but can also carry out fermentation or anaerobic respiration in an anaerobic environment
kinds of extremophiles
Acidophile: optimum pH at or below pH 3
Alkaliphile: optimum pH levels of 9 or above
Halophile: an organism requiring at least 2M of NaCl for growth
Barophile: organism that thrives at high pressures
mesophiles
do best in moderate conditions
many archaea are not ____
extremophiles
many bacteria and eukaryotes are ____
extremophiles
Describe the most common shapes of prokaryotes.
Coccus– spherical
Bacillus– rod-shaped
Spirilum – spiral-shaped.
prokaryotic characteristics
- Their DNA is not enclosed within a membrane and is usually a singular circularly arranged chromosome.
- Their DNA is not associated with histones (special chromosomal proteins found in eukaryotes); other proteins are associated with the DNA.
- They lack membrane-enclosed organelles.
- Their cell walls almost always contain the complex polysaccharide peptidoglycan.
- They usually divide by binary fission. During this process, the DNA is copied, and the cell splits into two cells. Binary fission involves fewer structures and processes than eukaryotic cell division .
How do prokaryotes reproduce?
Bacteria reproduce by binary fission. In this process the bacterium, which is a single cell, divides into two identical daughter cells. Binary fission begins when the DNA of the bacterium divides into two (replicates).
List and describe the three factors that contribute to the vast genetic diversity of prokaryotes.
- Rapid reproduction
- mutation
- genetic recombination
promote genetic diversity in prokaryotes
photoautotroph
energy source = light
carbon source = CO2
types of organisms = cyanobacteria, algae
chemoautotroph
energy source = inorganic chemicals (H2S, NH3, Fe2)
Carbon source = CO2
photoheterotroph
energy source = light
carbon source = organic compounds
types of organisms = aquatic and salt loving prokaryotes
chemoheterotroph
energy source = organic compounds
carbon source = organic compounds
types of organisms = protists, fungi, animals, some plants
What type of extremophile is a barophile?
is an organism which thrives at high pressures, such as deep sea bacteria or archaea
Acidophile
thrive under highly acidic conditions. These organisms can be found in different branches of the tree of life, including Archaea, Bacteria, and Eukarya
Alkaliphile
extremophilic microbes capable of survival in alkaline (pH roughly 8.5–11) environments, growing optimally around a pH of 10
Psychrophile
extremophilic organisms that are capable of growth and reproduction in low temperatures, ranging from −20 °C to +10 °C.
True or False: All extremophiles are Archaea, and all Archaea are extremophiles. Explain your answer.
False. Not all extremophiles are archaea.
Extremophiles include members of all three domains of life, i.e., bacteria, archaea, and eukarya. Most extremophiles are microorganisms (and a high proportion of these are archaea), but this group also includes eukaryotes such as protists
Genetic variation in bacterial populations cannot result from ____
meiosis.
but can result from mutation!
Photoautotrophs use ____
light as an energy source and CO2 as a carbon source.
_____ involves metabolic cooperation among prokaryotic cells?
biofilms
Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?
decomposer
Plantlike photosynthesis that releases O2 occurs in
cyanobacteria
what are the shapes of bacteria ?
spirillum- twists like a spiral
coccus- sphere shaped
bacillus- rod shaped
bacteria cell walls contain ____
peptidoglycan
Prokaryotes are not “primitive” but are _______
highly evolved!
barophile
organism that thrives at high pressures
halophile
an organism requiring at least 2M of NaCl for growth
Many bacteria (and eukaryotes!) are ______
extremophiles
Use universal _____ to amplify specific genes
primers
phototroph
obtain energy from light
chemotroph
obtain energy from chemicals
autotroph
need only CO2 or related compounds
heterotrophs
Organisms that get fixed carbon from organic compounds made by other organisms (by eating the organisms or their by-products)
require at least one organic nutrient such as glucose
chemolithotroph
uses inorganic reduced compounds such as hydrogen sulfide
chemolithoheterotrophs
using an inorganic chemical for their energy and electron needs, but relying on organic chemicals in the environment for their carbon needs. These organisms are also called mixotrophs, since they require both inorganic and chemical compounds for their growth and reproduction.
what do prokaryotes do for the ecosystem?
chemical recycling, decomposers
help the nitrogen cycle and decomposition
whats an example of bacterial mutualism?
bioluminescence
how do prokaryotes interact with humans?
used for PCR- polymerase chain reaction
bioremediation- use of organisms to remove pollutants from air, water and soil
