Block A Flashcards
what is the carbon cycle
decomposition of organic matter realising CO2 through respiration
what is the nitrogen cycle
converts nitrogen gas into forms that plants and animals can use such as ammonia, nitrite and nitrate
what is the sulphur cycle
some microorganisms can oxidize sulfur compounds, such as hydrogen sulfide (H2S), and convert them into sulfuric acid (H2SO4)
what is the phosphorus cycle
involved in the release of phosphate (PO43-) from minerals, which is an essential nutrient for plants and animals
iron cycle
some microorganisms can oxidize iron compounds, such as ferrous iron (Fe2+), and convert them into ferric iron (Fe3+)
what kind of microorganisms survive at high temperatures
thermophiles and hyperthermophiles can survive and grow at temperatures as high as 176°F (80°C) and even higher such as volcanic hot springs, geysers, and deep-sea hydrothermal vents.
what kind of microorganisms survive at low temperatures
psychrophiles can survive and grow at temperatures as low as -112°F (-80°C) such as polar ice, permafrost, and deep-sea sediments.
what kind of microorganisms survive at high pressures
piezophiles can survive and grow at pressures as high as 1,800 times atmospheric pressure such as deep-sea hydrothermal vents and subsurface oil reservoirs.
what kind of microorganisms survive at high salinities
halophiles can survive and grow in environments with very high salt concentrations, such as salt flats and salt mines.
what kind of microorganisms survive at high radiation
Deinococcus radiodurans can survive and grow in environments with high levels of radiation, such as nuclear waste sites and space.
what kind of microorganisms survive at high acidity
acidophiles can survive and grow in environments with very high acidity, such as acid mine drainage, acid hot springs, and acid soils.
structure of prokaryote
No membrane-enclosed organelles, no nucleus,
generally smaller than eukaryotic cells
structure of eukaryote
DNA enclosed in a membrane-bound nucleus
Cells are generally larger and more complex
Contain organelles
what kind of DNA is found within eukaryotic
linear found within the nucleus
what kind of DNA is found within prokaryotic cells
singular, circular DNA molecules called a chromosome
what is metabolism
chemical transformation of nutrients
what is reproduction
generation of two cells from one
what is differentiation
synthesis of new substances or structures that modify the cell
what is communication
generation of and response to chemical signals
what is evolution
the process of change over time that results in new varieties and species of organisms
what is phylogeny
evolutionary relationships between organisms, rRNA is excellent for determining phylogeny
Comparative rRNA sequencing has defined three distinct lineages of cells called domains:
bacteria (prokaryotic)
archaea (prokaryotic)
eukarya (eukaryote)
positive impacts of microbial activities on agriculture
nitrogen-fixing bacteria, cellulose-degrading microbes in the rumen, regeneration of nutrients in soil
negative impacts of microbial activities on agriculture
diseases in plants and animals
negative impacts of microorganisms on food
can cause food spoilage, many foods require methods of preservation
positive impacts of microorganisms on food
microbial transformations yield dairy products and other food products including sauerkraut, pickles, leavened breads and beer
who was first to describe microbes
Robert hooke (1635-1703)
what are homodimeric proteins
proteins composed of two identical polypeptides
what is the oldest known microorganism
fossilised stromatolites- 3.5 billion years ago
what is the mass of bacteria on earth
5x10^30 grams
what enzyme catalyses DNA supercoiling
DNA Gyrase
what is a chromosome
Large, encodes all essential genes and more
what are plasmids
small, many copies, non essential but advantageous genes (e.g. antibiotic resistance)
what are homedimeric proteins
proteins composed of two identical polypeptides
what are outcomes after DNA binding
DNA-binding protein may catalyze a specific reaction on the DNA molecule (i.e., transcription by RNA polymerase)
The binding event can block transcription
(negative regulation)
The binding event can activate transcription
(positive regulation)
what is an inducer
substance that induces enzyme synthesis
what is a corepressor
substance that represses enzyme synthesis
what are effectors
collective term for inducers and repressors
Effectors affect transcription indirectly by binding to specific DNA-binding proteins
Repressor molecules bind to an allosteric repressor protein
Allosteric repressor becomes active and binds to region of DNA near promoter called the operator
what are operons
cluster of genes arranged in a linear fashion whose expression is under control of a single operator
Operator is located downstream of the promoter
Transcription is physically blocked when repressor binds to operator
what is a repressor
can control enzyme induction, addition of inducer inactivates repressor, and transcription can proceed.
repressor’s role is inhibitory so its called negative control
what is negative control
a regulatory mechanism that stops transcription
what is positive control
regulator protein activates the binding of RNA polymerase to DNA
negative control repression
prevents the synthesis of an enzyme in response to signal, enzymes affected by repression make up small fraction of total proteins, typically effects anabolic enzymes and
negative control induction
production of an enzyme in response to a signal, typically affects catabolic enzymes, enzymes are synthesised only when they are needed
positive control activation
genes for maltose are spread out over the chromosome in several operons. each operon has an activator-binding site
global control systems
regulate expression of many different genes simultaneously
what is quorum sensing
mechanism by which bacteria assess their population density
what shape is coccus
spherical or ovoid
what shape is rod
cylindrical shape
phototrophs energy source
photosynthetic, energy from sunlight
chemotrophs energy source
energy from oxidation of chemicals
what is autotrophic
an organism that can make organic molecules from inorganic nutrients
what is heterotrophic
an organism that cannot make organic molecules from inorganic nutrients, depends on OM for energy generation and precursors for cell material
what are cyanobacteria
type of photoautotrophs that use hydrogen atoms from water to reduce carbon dioxide to form carbohydrates, produce oxygen gas
what are lichens
an association between two partners: an ascomycete (fungus) and a cyanobacterium.
Cyanobacteria provide organic compounds via photosynthesis, and can fix nitrogen
Fungus provides protection, water retention, extracts minerals and nutrients from substrate
what do chemoautotrophs do
fix carbon dioxide to make organic compounds, obtain energy from mainly inorganic chemicals
what are halobacteria
a type of photoheterotrophs, that possess the protein bacteriorhodopsin, light energy is used to transfer protons across the membrane out of the cell, resulting protein gradient is used to generate ATP, cannot fix CO2
what are chemoheterotrophs
the most common nutritional mode, uses organic compounds for both carbon requirement and energy generation. most bacterial pathogens are chemoheterotrophs
what is a regulon
multiple operons controlled by the same regulatory protein
who was first to describe bacteria
Antoni van Leeuwenhoek (1632-1723)
who founded the field of bacterial classification and discovered bacterial endospores
Ferdinand cohn (1828-1898)
