Chap. 27 Book Flashcards
What were the first organisms to inhabit earth?
Prokaryotes
Are most prokaryotes unicellular or multicellular?
Unicellular
What is the difference between the cell wall of prokaryotes and eukaryotes?
Prokaryotes have a cell wall which contains peptidoglycan
A polymer composed of modified sugars cross-linked by short peptides. Why is this term important to know?
Peptidoglycan
…encloses the entire prokaryotic bacterium
Name the three most common shapes of prokaryotes
Cocci, bacilli, Spirilli
What is the purpose of the Gram stain?
To categorize bacterial species according to differences in wall composition
What type of cell wall do gram-positive bacteria have?
Simple walls
Large amounts of peptidoglycan
A bacteria is structurally complex and has an outer membrane that contains lipolysaccharides. A gram stain is done. What will the result be?
Gram-negative
Why are gram-negative bacteria more resistant than gram-positive species to bacteria?
outer membrane impedes entry of drugs
A dense and well-defined and sticky layer of polysaccharide or protein
capsule
The Streptococcus bacterium attaches to cells in the respiratory tract. How does it do this?
capsule
What advantages does a capsule give to a prokaryote?
- adherence to substrate or individuals in a colony
- protect against dehydration
- shield from attacks by host
Certain bacteria develop resistant cells called _____ when they lack an essential nutrient
endospores
ENDOSPORE FORMATION
a. original bacteria cell produces a copy of its ___ and surrounds that copy with a tough multilayered structure = __________.
chromosome, endospore
What is the difference between fimbriae and pili? What is their common function?
Fimbriae are shorter and more numerous, connect two cells together
Fimbriae
a. hairlike appendages that attach cells to surfaces or e/o
b. appendages that pull two cells together prior to DNA transfer
a. hairlike appendages that attach cells to surfaces or e/o
Of the various structure that enable prokaryotes to move, the most common are what?
FLagella
What do structural and molecular comparisons indicate about the flagella of bacteria, archaea and eukaryotes? Would they be analogous or homologous?
they arose independently, analogous
T/F all prokaryotes are capable of taxis
False (50% are)
How could such a complex structure like the flagellum evolve?
bacterial flagellum originated as simpler structures that were modified in a. stepwise fashion over time
The bacterial flagellum may have evolved as other proteins were added to an ancestral secretory system. What is this process an example of?
Exaptation
The process in which existing structures take on new functions through descent with modification
Exaptation
The cells of prokaryotes are ______ than those of eukaryotes in their internal structure and DNA arrangement
simpler
Unlike eukaryotes, what do prokaryotes lack?
nucleus
a region of cytoplasm that is not enclosed by a membrane
nucleoid
smaller rings of independently replicating DNA molecules
plasmids
What two places carry genes in a prokaryote?
nucleoid, plasmids
What is the process of reproduction for a prokaryote?
binary fission
3 Key Features of Prokaryote Biology
a. they are ____
b. they reproduce by __________
c. they have ______ generation times
small, binary fission, short
Concept Check: rapid _______, _______ and _______ promote genetic diversity in prokaryotes
reproduction, mutation, genetic recombination
What is evidence that prokaryotes are not “primitive” or “inferior” in an evolutionary sense?
they rapidly adapt to new conditions
the combining of DNA from two sources
genetic recombination
How does genetic recombination occur in prokaryotes?
transformation, transduction, conjugation
What brings together prokaryotic DNA from different cells? If the cells are of different species, what is the specific term for this?
genetic recombination (transformation, transduction, conjugation), horizontal gene transfer
The genotype and even phenotype of a prokaryotic cell is altered by the uptake of foreign DNA from its surroundings
Transformation
A harmless strain of Streptococcus pneumonia can be transformed into pneumonia-causing cells if the cells are exposed to DNA from a pathogenic strain. What type of genetic recombination is here?
Transformation
Phages can carry prokaryotic genes from one host cell to another.
Transduction
An E. coli donor cell extends a pilus that attaches to a recipient cell.
Conjugation
DNA is transferred between two prokaryotic cells that are temporarily joined.
Conjugation
Why is the F factor important for conjugation-genetic recombination?
It consists of 25 genes
F plasmid-cells function as DNA donors
F- cells are DNA recipients
Chromosomal genes can be transferred during conjucation when the donor cell’s F factor is integrated into the chromosome
plasmids which carry resistance genes that code for enzymes that specifically destroy or hinder the effectiveness of antibiotics
R plasmids
CC 27.2
“Although rare on a per gene basis, new mutations can add considerable genetic variation to prokaryotic populations in each generation. Explain how this happens.”
“The large number of individuals in prokaryotic populations makes it likely that in each generation there will be many individuals that have new mutations at any particular gene, thereby adding considerable genetic diversity to the population.”
CC 27.2
“Distinguish between the three mechanisms of transferring DNA from one bacterial cell to another.”
a. Transformation - naked, foreign DNA from the environment is taken up by a bacterial cell
b. transduction - phages carry bacterial genes from one bacterial cell to another
c. conjugation - a bacterial cell directly transfers plasmid or chromosomal DNA to another cell via a temporary mating bridge
CC 27.2
“In a rapidly changing environment, which bacterial population would likely be more successful, one that includes individuals capable of conjugation or one that does not?”
Population with individuals capable of conjugation.
Some of its members could form recombinant cells whose new gene combinations might be advantageous in a novel environment
CC 27.2
“If a non-pathogenic bacterium were to acquire resistance to antibiotics, could this strain pose a health risk to people?”
Yes!
- genes for antibiotic resistance could be transferred (transformation, transduction, conjugation) from the nonpathogenic bacterium to a pathogenic bacterium
CC 27..2
“In general, how does DNA transfer among bacteria affect the spread of resistance genes?”
Transformation, transduction and conjugation tend to increase the spread of resistance genes
Which prokaryotes must use O2 for cellular respiration and cannot grow without it?
obligate aerobes
Prokaryotes that are poisoned by O2
obligate anaerobes
Process by which some prokaryotes extract chemical energy
anaerobic respiration
Prokaryotes that use 02 if present but can also carry out fermentation or anaerobic respiration
Facultative anaerobes
nitrogen fixation
some cyanobacteria and methanogens convert atmospheric nitrogen to ammonia
A Cyanobacteria that converts atmospheric nitrogen to ammonia is using what process?
Nitrogen fixation
What is essential for the production of amino acids and nucleic acids in all organisms?
nitrogen
T/F prokaryotes can metabolize nitrogen in many forms, but less so than Eukaryotes.
False
specialized cells that only carry out nitrogen fixation
heterocysts
Intercellular connections allow heterocysts to do what?
transport fixed nitrogen to neighboring cells
receive carbohydrates
Where does metabolic cooperation between different prokaryotic species often occur?
surface-coating colonies
biofilm
What surface-coating colony causes the capsule or slime layer of a prokaryotic cell wall to form?
Biofilm
CC 27.3
“Distinguish between the four major modes of nutrition.”
phototroph - energy from light
chemotroph - energy from chemicals
autotroph - carbon from CO2, HCO3-, etc.
heterotroph - carbon from organic nutrients
CC 27.3
“A bacterium requires only the amino acid methionine as an organic nutrient and lives in lightless caves What mode of nutrition does it employ?”
Chemoheterotrophy (bacterium must rely on chemical sources of energy, not exposed to light, must be heterotroph if it requires a source of carbon other than CO2 or HCO3-).
An aquatic and salt-loving prokaryote will employ what nutritional mode?
photoheterotroph
What type of organisms require at least one organic nutrient to make other organic compounds?
heterotroph
Organisms that only need CO2 or related compounds as a carbon source
autotroph
Which nutritional modes are unique to prokaryotes?
photoheterotrophic, chemoautotrophic
What does prokaryotic phylogeny show us?
genetic diversity in prokaryotes is immense
Prokaryotes that are more closely related to eukaryotes now belong in what domain?
archaea
Which domain of prokaryotes include “extremophiles”?
Archaea
prokaryotic “lovers” of extreme conditions
extremophiles
Orange and yellow colonies of prokaryotes grow in the hot water of Yellowstone National Park. What are they called (domain?)?
extreme thermophiles, Archaea
Archaean prokaryotes which thrive in VERY hot environments
extreme thermophiles
Archaean prokaryotes which thrive in highly saline environments
extreme halophiles
Methanogens
archaea that release methane as a by-product of their unique ways of obtaining energy
- Archea that use CO2 to oxidize H2
- poisoned by O2 (anaerobe)
methanogens
How have molecular systematics and metagenomics contributed to our understanding of the phylogeny and evolution of prokaryotes?
- indicate that organisms once classified as bacteria are more closely related to eukaryotes and belong in a domain of their own = archaea
- horizontal gene transfer is common and plays a role in the evolution of prokaryotes
- shows the immense diversity of previously unknown prokaryotic species
- metagenomic analysis may alter our understanding of phylogenetic analysis
What important role do chemoheterotrophic prokaryotes play in the ecosystem?
decomposers
- break down dead organisms
- unlock supplies of C, N, etc.
What function do autotrophic prokaryotes, like _____, play?
cyanobacteria, use CO2 to make organic compounds
- pass up organic compounds in a food chain
- increase availability of nutrients
Prokaryotes “immobilize nutrients by using them to synthesize molecules the remain within their cells. What is the result?
Prokaryotes decrease the availability of key plant nutrients
an ecological relationship in which two species live in close contact with each other
symbiosis
What is the larger organism in a symbiotic relationship called?
host
The smaller figure in a symbiotic relationship
symbiont
A prokaryote and its host typically participate in mutualism. Is this a positive event?
Yes
mutualism is an ecological interaction between two species in which both benefit
Mutualism is an ecological interaction between _______
two species
Commensalism: an ecological ____ in which one ____ benefits while the other is not ____ or _____ in any significant way
relationship, species, harmed, helped
an ecological relationship in which a parasite eats the cell contents tissues, or body fluids of its host
parasitism
What does a parasite do to its host?
eat the host’s cell contents, tissues, or body fluids
“The glowing oval below the eye of the flashlight fish ins an organ harboring bioluminescent bacteria. The fish uses the light to attract prey and to signal potential mates. The bacteria receive nutrients from the fish. The bacteria receive nutrients from the fish.” This is an example of what?
Mutualism
T/F As a group, parasites harm, but do not typically kill their host.
True
If a parasite causes a disease, is it a predator?
No, it is a pathogen
T/F Parasites that cause disease–pathogens–are all prokaryotic
False
CC 27.5 Explain how prokaryotes, though small, can be giants in their collective impact on Earth and life.
Because of their large numbers and metabolic abilities:
- decompose wastes
- recycle chemicals
- affects available concentration of nutrients for other plants
T/F Prokaryotic pathogens represent the largest majority of prokaryotic species
False
Many human intestinal prokaryotic species’ digest food that our own intestines cannot break down. What relationship do we have with such prokaryotes?
Mutualism (both species benefit)
T/F all pathogenic prokaryotes known to date are bacteria
True
Diarrheal disease and tuberculosis are examples of what type of prokaryote?
pathogenic prokaryotes (bacteria)
How do pathogenic prokaryotes typically cause illness?
Producing poisons - exotoxins or endotoxins
Pathogenic prokaryotes typically cause illness by producing poison–endotoxins or exotoxins. Difference:
Exotoxins–proteins secreted by bacteria and other organisms
Endotoxins-lipopolysaccharide components of the outer membrane of gram-negative bacteria
A pathogenic prokaryote produces a poison that is released when bacteria dies and the bacteria’s cell walls break down. What poison is this?
Endotoxin
Lipopolysaccharide components of the outer membrane of gram-negative bacteria
Endotoxin
Cholera and botulism is an example of what poison-protein?
Exotoxin
A bacteria is gram-negative. What poison is housed in its outer membrane?
Endotoxins
Name one positive way to harness prokaryotes:
bioremediation
Anaerobic bacteria and archaea decompose the organic matter in sewage —> landfill or fertilizer material. What is this an example of?
Bioremediation :)
Name two reasons why prokaryotes are useful?
They have diverse forms of nutrition and metabolism
CC 27.6
“Identify at least 2 ways that prokaryotes have affected you positively today.”
a. eating fermented foods
b. clean water from sewage treatment
c. medicines prod. by bacteria
CC 27.6
“A pathogenic bacterium’s toxin causes symptoms that increase the bacterium’s chance of spreading from host to host. Does this information indicate whether the poison is an exotoxin or endotoxin?”
No. If the poison is secreted as an exotoxin, live bacteria could be transmitted to another person. But the same is true of the poison is an endotoxin–only in this case, transmitted live bacteria may be descendants of the (now-dead) bacteria that produced the poison.
CC 27. 6
“How might a change in your diet affect the diversity of prokaryotic species that live in your digestive tract?”
“Because different prokaryotic species have different adaptations, a change in diet may alter which species can grow most rapidly, altering species abundance.”
PARTS OF PROKARYOTIC CELL STRUCTURE
a. _____: hairlike appendages that help cells to adhere to other cells or to a substrate
b. _____: sticky layer of polysaccharide or protein that can help cell adherence/evasion
c. internal organization: no ___ or other ____-____organelles
d. _______: structures used by most motile bacteria for propulsion; taxis
e. ______ _____ found in nearly all prokaryotes; structure differs in gram-positive/negative bacteria
f. circular ______: often accompanied by smaller rings of ____ called _______
g. ____: appendage that facilitates conjugation
fimbriae, capsule, nucleus, membrane-bound, flagella, cell wall, chromosome, DNA, plasmids, pilus
CR 27.2
Rapid ______, ______, and ________ can promote genetic diversity in prokaryotes.
- recombination of DNA from two different cells: ___, _____, ______-
reproduction, mutation, genetic recombination, transformation, transduction, conjugation
CR 27.3
___________ is much higher in prokaryotes than in eukaryotes
T/F as a group, prokaryotes form all four modes of nutrition
Among prokaryotes, _________ require O2, _______ are poisoned by O2, _______ can survive with or without O@
nutritional diversity, True, obligate aerobes, obligate anaerobes, facultative aerobes
Unlike eukaryotes, prokaryotes can metabolize _____ in many forms. Some can convert _____ _______ to ____, a process called _____ ______
nitrogen, atmospheric nitrogen, ammonia, nitrogen fixation
Metabolic cooperation occurs in surface-coating ____ that include different species
biofilms
The two largest nutritional types of bacteria
proteobacteria, gram positive bacteria
Some archaea, like ______ and ______, live in extreme environments
extreme thermophiles, extreme halophiles
CR 27.5
“decomposition by ______ prokaryotes and the synthetic activities of _____ and nitrogen-fixing ____ contribute to the recycling of elements in ecosystems”
heterotrophic, autotrophic, prokaryotes
Many prokaryotes have a ____ relationship with a host
symbiotic
People depend on ____ prokaryotes.
mutualistic
Pathogenic bacteria typically cause disease by releasing ____ or _____.
endotoxins, exotoxins
What can spread genes associated with virulence to harmless species or strains?
horizontal gene transfer
