Ch. 1 - Evolution Of Microorganisms And Microbiology Flashcards
What are the beneficial roles of bacteria?
- they have a global impact and maintain human health
- they breakdown dead plant and animal material which cycles elements in the biosphere
- they are used extensively and industry to make bread, cheese, antibiotic’s, vitamins, enzymes, and other products
What does the domain eukarya include?
Microorganisms classified as protists or fungi; animals and plants are also placed in this domain
Microorganisms
Organisms and acellular biological entities too small to be seen clearly by the unaided eye
Viruses
- Acellular entities that must invade a host cell to multiply
- composed only of proteins and a nucleic acid
- can be extremely small
- cause many animal and plant diseases and have caused epidemics that have shaped human history
What are the simplest viruses composed of?
Proteins and a nucleic acid
How do viruses multiply?
They must enter host cells
What group of organisms has the greatest number of taxa?
Microbes
What is the main difference between prokaryotic and eukaryotic cells?
Prokaryotic cells lack a nucleus and membrane-bound organelles
•they also have plasmids which contain their DNA as opposed to chromosomes
What are enzymes?
Catalytic proteins that speed up the myriad of chemical reactions that occur in cells
Bacteria
- usually single celled organisms
- most have cell walls that contain the structural molecule peptidoglycan
- most exhibit typical prokaryotic cell structure (i.e., they lack a membrane-bound nucleus), a few members of the unusual phylum Planctomycetes have their genetic material surrounded by a membrane
- lack a nucleus and membrane bound organelles
What entities in the field of microbiology are considered cellular?
•Fungi -yeast -molds •protists -algae -Protozoa -slime molds •bacteria -escherichia coli •archaea -methanogens
What entities in the field of microbiology are considered acellular?
•viruses -consists of: protein and nucleic acid •virolds - consists of: RNA •satellites -consists of: nucleic acid, often RNA •prions -consists of: protein
How can some microorganisms be macroscopic?
Because they are multicellular
What are the three characteristics of cellular microbes?
- usually smaller than 1 mm in diameter
- often unicellular
- If multicellular, lack differentiated tissues
What is the role of membrane-bound organelles in eukaryotic cells?
Separate some cellular materials and processes from others
What are the five kingdoms of life?
- monera
- protista
- fungi
- animalia
- plantae
LUCA
Last Universal Common Ancestor
3 domains of cellular organisms
- Bacteria
- Archaea
- Eukarya
Bacteria roles
- making of bread and cheese
- cycle elements in biosphere
- break down dead plant material
- produce vitamins and minerals
Archaea features
- distinctive rRNA sequence
- lack peptidoglycans in their cell walls
- unique membrane lipids
- some have unusual metabolic characteristics, such as methanogens, which generate methane (natural) gas
- found in extreme environments, including high temps (thermophiles) and high salt concentrations (extreme halophiles)
Protists
Eukaryotic organisms
What was present in the atmosphere of early Earth?
•water vapor •carbon dioxide •nitrogen •in the oceans: -hydrogen -methane -carboxylic acids
What are the roles of proteins?
•structural
•catalytic
-enzymes
Ribozymes
Catalytic RNA molecules; can do both cellular work and replicate itself
What is the importance of cyanobacteria?
- released oxygen into earths atmosphere
* allowed for aerobic respiration
Endosymbiotic hypothesis
•The origin of three eukaryotic organelles:
-mitochondria
-chloroplasts
-hydrogenesomes
• an interaction between two organisms in which one organism lives inside the other
• has been modified to suggest that the host became dependent on the gas hydrogen produced by the symbiont
How does the Endosymbiotic hypotheses occur?
•overtime a bacterial endosymbiont of an ancestral cell in the eukaryotic linage lost ability to live independently becoming either:
- mitochondrion if aerobic respiration was used
- chloroplast if photosynthesis was used
Hydrogen hypothesis
- modified for mitochondrion
* asserts that endosymbiont was anaerobic bacteria that produced H2 and CO2 as end products of metabolism
How do most eukaryotic species increase diversity?
By reproducing sexually
How do most bacterial and archaeal species increase their diversity?
Horizontal gene transfer
* they do not reproduce sexually
How does horizontal gene transfer occur?
- Genetic information from a donor organism is transferred to a recipient, creating a new genotype
- Thus genetic information can be passed from one generation to the next as well as between individuals of the same generation and even between different microbial species
Strains
- consists of the descendants of a single, pure microbial culture
- strains within a species may be described in a number of different ways
How do microbiologists name microbes?
- by using the binomial system of the 18th century biologist Carl Linnaeus
- The first part of the name which is capitalized is the generic name (i.e., The name of the genus to which the microbe belongs)
- The second part of the name which is uncapitalized is the species epithet
Pure or axenic culture
A distinct feature of microbiology in which microbiologist remove microorganisms from their normal habitats and culture them isolated from other microbes
Who is Robert Hooke?
- He is credited with publishing the first drawings of micro organisms in the scientific literature
- “Micrographia” was his book; One of the designs discussed in this book was probably a prototype for the microscopes built and used by the amateur microscopist Anthony van Leeuwenhoek
Who was Anthony van Leeuwenhoek?
- spent his spare time constructing simple microscope’s composed of double convex glass lenses held between two silver plates
- his microscopes could magnify about 50 to 300 times, and he may have illuminated his liquid specimens by placing them between two pieces of glass and shining light on them at a 45° angle to the specimen plane