Part 1 - Microbiology And Microorganisms Flashcards
Microbiology is defined by what techniques
Culture media for isolation and growth of an organism in pure culture
Biochemical to study cell components
Molecular and genetic techniques
Oldest form of life
Microbes
Largest mass of living material on earth
Microbes
Why is microbiology important?
Carry out major processes for biochemical cycles
Can live in places unsuitable for other organisms
Other life forms require microbes to survive
All cells have
Cytoplasmic membrane
Cytoplasm
Ribosomes
Cytoplasmic membrane
Barrier that separates the inside of the cell from the outside
Cytoplasmic
Aqueous mixture of macromolecules, ions, and proteins
Ribosomes
Site of protein synthesis
Genetic material
Stored as DNA
Information is divided into functional units called genes
Genome
A cell’s full complement of genes
Plasmid
Piece of DNA that carries non-essential genes
Eukaryotes have
Membrane bound nucleus
Membrane bound organelles
Complex internal organization
Division by mitosis and meiosis
Protists
Unicellular or multicellular without differentiation into tissues
Types of protists
Protozoa
Algae
Slime molds
Protozoa
Animal-like microorganisms
Algae
Photosynthetic plant-like microorganisms
Slime molds and water molds
Filamentous
Fungi
Unicellular - yeasts
Filamentous- molds
Multicellular- mushrooms
Prokaryotes
No membrane bound nucleus or organelles Generally smaller 1 micrometer Simple internal structure Divide by binary fission Most are unicellular
Bacteria
Genetically diverse
Extremely diverse metabolic styles
Both pathogens and non-pathogens
Archaea
Genetically and biochemically distinct from bacteria
Diverse metabolism
Never pathogenic
Live in extreme environments
Viruses
Acellular infectious particles
Extremely small
Obligate intercellular parasites
Lack independent metabolism- no ribosomes, no ribosomal DNA, not classified with other microbes
First anaerobic life
Between 3.8 and 3.9 billion years ago
Photosynthetic bacteria oxygenated the earth
2 billion years ago
What allowed the evolution of modern eukaryotic microorganisms?
Oxygenation of the earth
First plants and animals appeared
0.5 billion years ago
Prokaryotes ribosomes
70s and 16S ssu rRNA
Eukaryotes ribosomes
80s and 18s ssu rRNA
rRNA
Change slowly over time
Examine genetic differences rather than morphological differences
Basic steps involved in sequencing rRNA genes
Step 1 - DNA is collected from a pure culture
Step 2 - the SSU rRNA is amplified using polymerase chain reaction
Step 3 - gene is sequenced
Step 4 - sequence is aligned with sequences from other organisms
- number of differences is used to calculate evolutionary distance
PCR
A technique used to synthesize many identical copies of a short sequence of DNA
Phylogenetic tree
A graphic representation of the evolutionary distance between organisms
Phylogenetic tree based on
16S or 18S ribosomal DNA sequences
Most genetically diverse
Microorganisms
Phylogenetic species concept
A group of strains that share certain diagnostic traits, are genetically cohesive and have a unique recent common ancestor
Species of bacteria and archaea should have
Most characteristics in common
Greater than 97% sequence similarity in the 16S rRNA gene
High degree of genome similarity
- DNA-DNA hybridization
Hierarchical classification
Groups of organisms are placed in successively larger groups
Species, genus, phylum
Robert Hooke
First to describe microbes
What is microbiology?
Study of organisms too small to be seen with the naked eye
What kind of microscope did Robert Hooke use?
Compound microscope with 2 lenses with up to 30x magnification
What did Robert Hooke observe?
Cells in cork
Bread mold filaments
What was the first microbe observed?
Bread mold filaments
Cell Theory
All living things are composed of cells
Antoni van Leeuwenhoek
Built microscopes that magnified by 50-300x
Observed single called microorganisms, “animalcules” - first discovery of bacteria
Louis Pasteur
Studied wine and beer production
Fermentation
Yeast will convert sugar to alcohol without oxygen
Souring wine is caused by
Bacteria converting alcohol to acid
Pasteurization
Gentle heating to kill unwanted bacteria
Pasteur and Spontaneous Generation
- Prepared meat infusions inside of long swan-necked flasks
- Boiled the infusion to sterilize it
- As long as the flask remains upright, dust, and microbes cannot enter, and the infusion remains sterile
Aseptic technique
Methods for controlling the growth of microorganisms
What did Robert Koch study?
Anthrax - responsible for epidemics in livestock
Koch’s postulates
Established set of criteria for relating a specific microbe to a disease
Broth medium solidified with agar
Polysaccharide derived from marine algae
What temperature does agar melt at?
97c
What temperature does agar solidify at?
43c
Typical Petri plate
Nutrient broth medium + 1.5% agar
Colony
Mass of cells that (ideally( rose from one single cell
Significant and insignificant numbers
300 - inaccurate count
