CH19 and 31 Flashcards
Haeckel placed bacteria in the kingdom
Protista
An infection thread
is formed by the plant root hair cell
A classification system based on mutual similarity that involves comparing as many characteristics as possible is called a __________ system.
phenetic
A classification system based on evolutionary relationships is called a __________ system.
phylogenetic
All of the following are true of Mycoplasmas EXCEPT
they may reproduce by budding
they have a thin layer of peptidoglycan in their walls
they are pleomorphic
they are chemoorganotrophs
they have a thin layer of peptidoglycan in their walls
The reason coral reefs are among the most productive and successful ecosystems is due to
the coral-dinoflagellate mutualistic relationship.
Which of the following is NOT a legume?
lentils
peas
soybeans
wheat
clover
wheat
The region of soil in the immediate vicinity of the roots of plants is called the
rhizosphere.
A population descending from a single organism or pure culture isolate is called a
strain
Which of the following is an example of the use of the binomial system devised by Linnaeus?
Escherichia coli
Stable annealing due to hydrogen bonding between DNAs of similar nucleotide sequence from different organisms is referred to as
hybridization.
Which of the following is true about Bergey’s Manual?
The first and second editions are both largely phenetic.
The first edition is mostly phenetic while the second edition is more phylogenetic.
The first edition is largely phylogenetic while the second edition is more phenetic.
The first and second editions are both largely phylogenetic.
The first edition is mostly phenetic while the second edition is more phylogenetic.
All the following are true of bacteroids EXCEPT
they tend to vary in shape due to the loss of a cell wall
they are the site of nitrogen fixation
they respond to a flavonoid signal
they are surrounded by a plant derived membrane
they respond to a flavonoid signal
In the Whittaker classification, bacteria were placed in kingdom ____
Monera
Rhizobium and Bradyrhizobium are significant contributors to which process when engaged in a symbiotic relationship with leguminous plants?
nitrogen fixation
Which of the following is true regarding Whittaker’s classification of viruses
he did not include them in his classification system
The determination of the taxon to which an organism belongs is called
identification.
In a mycorrhizal relationship, the fungal component can assist in providing phosphorus and water to the plant. The plant in turn provides the fungus with
organic carbon.
A rhizobium inoculant
can be applied to seeds prior to planting
contains a highly effective bacterium in a peat carrier
is generally inexpensive
The Haber-Bosch process
is used to produce nitrogen fertilizer.
All the following are true of rhizobia EXCEPT:
they are readily cultivated on yeast mannitol media
they do not fix nitrogen in laboratory cultures
they are motile soil bacteria
they are Gram positive bacilli
they are Gram positive bacilli
Nodules are red inside
because of the presence of leghaemoglobin
Which of the following is NOT a unique characteristic of members of the Archaea?
No thymine in tRNAs
Membrane lipids containing ether-linked glycerol phytanols
70S ribosomes
Methane transformations
70S ribosomes
The temperature at which half of the strands of a double-stranded DNA molecule have separated from each other is called the __________ temperature.
melting
The assignment of names to taxonomic groups is referred to as
nomenclature
order to 10 million + specied
taxonomy
organize/form groups based on similarities or evolutionary relatedness
classification
determine where an isolate belongs based on morphology, physiology, genetics
identification
naming binomial systems of Linnaeus
nomenclature
similar strains
species
closely related species
genus
Linnaeus taxonomy classification
- plantae- plants, algae, fungi (bacteria)
- animalia- microorganisms
Haeckel taxonomy classification
- plantae- plants multicellular algae
- animalia- animals
- protista- microorganisms
Whittaker taxonomy classification
- plantae- multicellular, photosynthetic
- animalia- multicellular, ingest food
- fungi- uni/multi cellular, absorb food
- protista- unicellular, eukaryotes
- monera- prokaryotes
Woese taxonomy classification
- archaea bacteria (archaea)
- eubacteria (bacteria)
- eucaryotes
**domains; higher classification than kingdoms
grouped on overall similarities
phenetic classification
- many characteristics (50-100)
- each given equal weight
- morphology, physiology, biochemical
numerical taxonomy
grouped on probable evolutionary relationships
- difficult with out MO
- little/no fossil record
- AA sequences in proteins
- rRNA nucleotide sequence
phylogenetic classification
characteristics fro identification
morphological
physiological/metabolic
ecological
molecular characteristics
size, shape, colony type, staining traits, cilia, flagella, motility, endospores, color
morphological
- C, N, energy sources
- fermentation
- nutrient type
- temp, O2, pH,- tolerance changes
- sensitivity to inhibitors/antibodies
physiological/metabolic
- life cycles
- symbiotic relationships
- disease induction- host range
- habitat preferences
ecological
- nucleic acid base composition (G-C content)
- nucleic acid hybridization
- nucleic acid sequencing
- genomic fingerprinting
molecular characteristics
- specific spectrometer that moitors absorbance at 260 nm
- SS absorb more than DS DNA
- as temp increases, DS will separate and melt which increases the absorbance
nucleic acid base composition (G-C content)
High G-G content will have a higher melting temp bc
they have 3 H-bonds holding them together
- melt DNA of two MOs to form SS
- measure how much re-associates
- more annealing (more related to the MOs; complementary and able to hybridize)
- renature DNA below Tm
nucleic acid hybridization
- introduced by Woese
- techniques now widely available
- SSU rRNA
- some essential function, change slowly with time, not effected by horizontal gene transfer
-nucleic acid sequencing
RFLP analysis
-genomic fingerprinting
- phenetic classification
- gram - stain reactions
- sections- shape, O2, motility, energy
- gram +, gram -, mycoplasmas
Bergey’s manual of systematic bacteriology 1st edition
- phylogenetic classification
- rRNA studies, many more species and genera
- significant changes (especially gram -)
- evolutionary classification
Bergey’s manual of systematic bacteriology 2nd edition
mutualistic symbiosis with MOs and animals
-cellulose degradation
-light production
-photosynthesis
-lithography
AA biosynthesis
mutualistic symbiosis with MOs and plants
- phosphorus acquisition
- N2 fixation- extremely stable and unreactive at ambient temps, not usable by members of eukarya, most limiting
two ways to reduce or fix nitrogen gas to ammonia
- Haber Bosch fertilizer fossil fuels (ex: urea)
- symbiosis with N2 fixing bacteria sunlight (Rhizobiaceae)
important grain and pasture crop and have high protein
legumes
- soil bacteria, gram -, motile rods
- ex: Rhizobium, Bradyrhizobium
Rhizobia
culturing yeast mannitol media with indicators
- not very fastidious in nutritional requirements
- do not fix N2 in free living state
- yeast: growth factor, vitamins, fixed N2
- mannitol: carbon and energy
- indicators: congo red (used to differentiate b/t two types of rhizobia
culturing yeast mannitol media with indicators
- not very fastidious in nutritional requirements
- do not fix N2 in free living state
- yeast: growth factor, vitamins, fixed N2
- mannitol: carbon and energy
- indicators: congo red (used to differentiate b/t two types of rhizobia
specificity of symbiosis
- not all legumes form a symbiosis with all rhizobia
- some are very specific (soybeans)
- some are more promiscuous (cowpeas)
not picky about establishment of symbiosis
promiscuous
classification of specific and promiscuous legumes were originally based on
host phage
Root Nodule Formation by infection process
- The plant root releases flavonoids that stimulate the production of Nod gene expression
- Attachment of bacterial cells to root hairs involves rhicadhesins and host plant lectins that affect the pattern of attachment and nod gene expression.
- Structure of a typical Nod factor that promotes root hair curling. Nod factors enter root hairs and migrate to their nuclei.
- A plant root hair with attached rhizobium undergoing curling. Initiation of bacterial penetration into the root hair cell and infection thread growth
- release of rhizobia, formation of bacteroids surrounded by plant-derived peribacteroid membranes and differentiation of bacteroids into nitrogen-fixing symbiosomes.
- vary in size and shape depending on bacteria in legume
- can be determinate or indeterminate
nodules
- circular
- form, function, disintegrate
determinate nodule
- anuals (clover, alfalfa)
- can continually grow
indeterminate nodule
during nodulation:
plants produce-
bacteria produce-
- plants- infection thread, flavenoid process
- bacteria- Nod factors (stimulate growth), initial curling and softening of cell wall
in N2 fixation, ammonia is incorporated in amides and/or ureides. give an example of each
- amides- beans
- ureides- chickpeas
describe nitrogenase
a 2 component enzyme (MOFE and FE) that can reduce other substrates (acetylene to ethylene) and inactivated by O2
active nodules contain
leghemoglobin
oxygen problem in N2 fixation
free oxygen levels are low, but oxygen available for respiration
- for pasture and soil improvement
- mixtures, rotations, protein banks
plant legumes
the symbiosis mutualism between plants and rhizobia
- plant receives fixed N2 from bacterium
- rhizobia receive carbon/energy and protection from the plant
select plant varieties that form an effective symbiosis
plant breeding for improvement
adding highly effective rhizobia to the soil/seed
Rhizobia inoculant production and use
benefits of Rhizobia inoculant
- not expensive ($1-5 per ha)
- well nodulated soybean fixes
