Principles Of Microbiology Flashcards
What are the four classes of cellular molecules?
Proteins, nucleic acids, lipids and polysaccharides.
Six characteristics of living organisms.
Compartmentalization and metabolism, growth and reproduction, differentiation, communication, movement and evolution.
Compare machine and coding functions of microbial cells.
Machines: metabolism and enzymes accelerating it.
Coding devices: store and process DNA.
They dependent on each other and have to be highly coordinated in order to provide growth and reproduction.
What a microbial habitat?
It’s the environment in which the cell population lives.
What differs microbial community from microbial population?
Population: a group of cells originated from the same cell.
Community: populations interacting.
How can microrganisms change the characteristics of their habitats?
They remove and excrete nutrients to their habitats. They are therefore open systems.
Were the earliest life forms cellular?
No, there were small molecules of RNA able to replicate themselves.
Why is it that cellular life is the only form of life we see on Earth today?
They hold the fundamental characteristics of life so they were selected.
How old is Earth and when did cellular life forms first appear?
It’s 4.6 billion years old and the first cellular life (methanogens & other anaerobic organisms) is 3.8 billions years old.
How can we use science to reconstruct the sequence of organisms that appeared of Earth?
Using biomarkers that can be identified in ancient rocks.
Where are most microbial cells located on Earth?
Undergroung in oceans and terrestrial subsurfaces.
In what ways are microorganisms important in the food and agricultural industries?
Fermentation, food preservation, Nitrogen metabolism (nodules in legumes’ roots) and rumen.
List two fuels that are made by microorganisms.
Methane and ethanol.
What is biotechnology?
It’s the genetic modification of microorganisms in order to enable them to produce commercial items such as insulin and other hormones.
What major discovery emerged from Cohn’s study of hear resistance in microorganisms?
Bacteria that form endospores.
Define term sterile.
Sterile is a medium where there are no microorganisms.
How did Pasteur’s swan-neck flask experiment show that the concept of spontaneous generation was invalid?
The fresh air without the microorganisms was unable to create life, which appeared only when the sterile liquid was in touch with microorganisms.
How do Koch’s postulates prove cause and effect for the culture of microorganisms?
By inoculating microorganisms present in sick animals into health animals.
What advantages do solid media offer for the culture of microorganisms?
They enable colonies to grow and make easy to identify then.
What is a pure culture?
It is a culture originated from one single cell.
What is the enrichment culture technique?
It’s a selection of microorganisms by manipulating nutrient and incubation conditions.
What’s chemolithotrophy?
It’s the oxidation of inorganic compounds such as ammonia and CO2 linked to energy conservation. Therefore some microorganisms can produce ATP from them.
How might you distinguish a phototrophic microorganism from a chemotrophic one by simply looking at it under a microscope?
The photrothopic ones are colourful because of their pigments.
What are extremophiles?
Microorganisms that require extreme conditions to survive such as high temperatures and salty environments.
What is the largest phylum of Bacteria?
Proteobacteria.
Why can it be said that the cyanobacteria prepared Earth for the evolution of higher life forms?
Because they oxigenated the Earth.
What is physiologically unique about Deinococcus?
Their resistance to radiation.
What is unusual about Halobacterium?
They can produce ATP from light in a distinct way than other phototrophs.
What group of Archea is responsible for producing the natural gas we use as a fuel? Chemically, what is natural gas?
Methanogens. Methane.
How can we know the microbial diversity of a natural habitat without first isolating and growing the organisms it contains?
By rRNA sequences.
List two ways algae differ from cyanobacteria.
They have chloroplasts and they can inhabit soil.
List two ways algae differ from protozoa.
They have cell wall and they are phototrophs.
How do each of the components of a lichen benefit each other?
Algae or cyanobacteria provide nutrients and fungi provide protection.
Why have rocks dating to the origin of Earth not been found?
Because the materials were condensed due to energy released by nuclear fusion.
What do crystals of the mineral zircon tell us about when the first oceans may have formed?
They have traces of oxygen.
What does the possible presence of liquid water on Earth 4.4 to 4.3 billion years ago suggest about the origin of life?
The conditions were compatible with life already.
What roles did the mounds of mineral-rich materials warm hydrothermal springs play in the origin of life?
They provided stable conditions for life.
What important cell structure was necessary for life to proceed from a possible RNA world to cellular life?
Lipid membranes.
How could cells have obtained energy from Fe + H2S?
Reducing it which is an exergonic process.
Why is the advent of cyanobacteria considered a critical step in evolution?
Because the oxygenated the Earth.
In what form is iron present in banded iron formations?
Ferric iron.
What role did ozone play in biological evolution, and how did cyanobacteria make the production of ozone possible?
It permitted life in sunlight exposed areas. Cyanobacteria produces oxygen, that is converted in ozone when exposed to UV radiation.
What evidence supports the idea that the eukaryotic mitochondrion and chloroplast were once free-living members of the domain Bacteria?
Morphologic, genetic and phylogenic similarities.
In what ways are modern eukaryotes a combination of attributes of Bacteria and Archaea?
They have the type of lipids found in Bacteria as well their energy metabolism mechanisms. They transcription and translation apparatus is similar to Archaea’s.
According to the Darwinian view of life, all organisms are related by…
An ancestor.
What class of mutation is most common?
Neutral.
Why are SSU rRNA genes suitable for phylogenetic analysis?
- universally distributed
- functionally constant;
- sufficiently conserved;
- adequate length.
What information does the RDP-II provide?
rRNA gene sequences.
What value do molecular clocks have in phylogenetic analysis?
It gives an approximated time between mutations.
How are DNA sequences obtained for phylogenetic analysis?
PCR.
What does a phylogenetic tree depict?
The order of descent and the ancestry of the nodes.
Why is sequence alignment critical to phylogenetic analysis?
Because it defines how closely related are the species.
What are signature sequences?
Exclusive rRNA sequences within a domain, genus or single species.
How can oligonucleotide probes be made visible under the microscope? What is this technology called?
By attaching a fluorescent dye to it (FISH).
What kind of questions can be addressed using a microbial community analysis?
What species are in that environment.
How is ribotyping able to distinguish between different bacteria?
By different cuts in DNA.
What is FAME analysis?
Analysis of fatty acids proportions in cell membrane.
What are some of the drawbacks of FAME analysis?
It requires rigid standardization and specific growth conditions.
How do AFLP and MLST differ from ribotyping?
They focus in variations in DNA sequence throughout the genome..
What limits the value of 16S rRNA gene or any gene in taxonomy?
Too conserved.
What is the meant by the term monophyletic?
A group descended from one ancestor.
What’s an ecotype?
A population of cells that compete for the same key nutrients.
