Chapter 1 The Microbial World Flashcards
Microscopy
seeing microbes and their structures
Cultivation and physiology
growing microbes and studying what they do
Molecular Biology and Genetics
studying cell structures and molecules, their function, inheritance, and regulation
Genomics
studying cellular information
Robert Hooke (1635-1703)
first to describe microbes
Antonie Van Leeuwenhoek (1632-1732)
first to describe bacteria
Louis Pasteur (1822-1895)
First to culture microbes, disproved spontaneous generation, proposed germ theory, invented pasteurization, developed rabies vaccination
Spontaneous Generation
The theory that life arises spontaneously from non-living mater
Miasma Theory of Disease
The theory that disease was caused by ‘bad air’ from the unclean conditions
Correlation but not causation
Sterile
free form living organism
Inoculate
to add a biological entity into a system
Medium
a material used to grow microbes
Only when sterile media is inoculated does…..
bacterial growth occur
Pasteur used ____ and/or ______ to sterilize growth media
Heat
porcelain filters
Robert Koch (1843-1910)
developed pure culture techniques, proved germ theory of diseases (using Koch Postulates)
Solid Media
allows for isolation of colonies (Hesse and Petri)
Pure Culture
A growing collection of cells derived from a single type of microorganism
Colonies vs Cells
Colonies made up of millions of cells
Koch’s Postulates
- The suspected pathogen must be present in all cases of the diseases and absent from healthy animals
- The suspected pathogen must be grown in pure culture
- Cells from a pure culture of the suspected pathogen must cause disease in a healthy animal
- The suspected pathogen must be reisolated and shown to be the dame as the original
Golden Age of Microbiology
Increase in non-microbial diseases and decrease in infectious diseases
Martinus Beijerink (1851-1931) and Sergei Winogradsky (1856-1953)
Developed enrichment culture techniques and linked microbial processes to nutrient cycles
Enrichment Culture
uses defined media designed to grow specific microbes
What type of respiration is used by Animals and most fungi?
Aerobic respiration
What type of respiration is used by Plants?
Photosysthesis
What type of respiration is used by Microbes?
Aerobic respiration, anaerobic respiration, fermentation, syntrophy, lithography, diverse forms of photo-trophy, respiration of metals and sulfur and methane
Kluyver (1926)
publishes Unity of Biochemistry; “from elephant to butyric acid bacterium - it is all the same” by 1944 - E coli has become a model organism
Why is E. coli for example a model organism
DNA is fundamental; humans and microbes have it so it can be used for comparison
Escherichia coli (E. coli)
a bacterial species used as model organism to discover the molecular nature of life
easy to grow, versatile, grows fast, and is readily cultivated form human stool
Watson, Crick, and Franklin (1953)
discover structure of DNA
Sanger (1977)
develop a method for sequencing DNA
Woese (1977)
builds the first Tree of Life from rRNA sequences
Ribosomes
Complex macromolecules that make proteins, present in ALL cellular life
Ribosomal RNA (rRNA)
the major component of ribosomes, which contain 16S rRNA, 23S rRNA, and 5S rRNA
Classification Prior to Molecular Phylogeny
- Plantae
- Fungi
-Animalia - Protista
- Monera
Molecular Phylogeny
Using the sequences of molecules to study the evolutionary history of life
Mullis (1985)
invents the Polymerase Chain Reaction (PCR)
Pace (1985)
cultivation independent techniques using rRNA
PCR
a method of obtaining specific DNA segments for study
Genome sequencing
a method for determining the DNA sequence of a genome from one organism
Metagenomic sequencing
a method for determining the DNA sequences of all genomes in a community
Bright field microscopy
has low contrast and so requires staining to see bacteria
Contrast
difference in light intensity between image and background
Resolution
ability to differentiate adjacent objects
Stains
increase contrast (e.g. methylene blue, safranin, and crystal violet)
Simple Stains
stain cells indiscriminately
Compound stains
differentiate structures
Phase-contrast microscopy
increases contrast of live bacteria
Dark-field microscopy
increases contrast of refractile samples
Light Microscopy
- bright-field
-phase-contrast
-dark-field
Fluorescence microscopy
- bright-field
-fluorescence
Electron Microscopy
-TEM
-SEM
Transmission Electron Microscopy (TEM)
pass electrons through sample instead of light; visualize cell structures in sectioned samples, 2D image, thin sample
Scanning Electron Microscopy (SEM)
coat specimen with metal, view electrons that bounce off sample surface, 3D image of surface
Metabolic rates vary _______ in relation to the square of the cell size
inversely
Prokaryotic Cells
bacteria and archea
0.2-700 um
no organelles required, rely on diffusion for intracellular transport
No nucleus, DNA forms “nucleoid”
Eukaryotic Cells
Eukarya
2um-10cm
contains organelles, which facilitate intracellular transport and allow cells to escape diffusional limitation
DNA enclosed in a membrane-bound nucleus
Viruses
0.02um-0.6um
NOT CELLS!!!
- No cytoplasmic membrane, cytoplasm, or ribosomes
- viral genomes can be double or single stranded DNA or RNA
-smaller than cells (generally)
-viral genomes are encased in a capsid shell and/or an envelope
-cannot conserve energy
-obligate parasites
Organelles in a Prokaryotic Cell
Cell wall, cytoplasmic membrane, nucleoid, cytoplasm, plasmid, ribosomes
Organelles in a Eukaryotic Cell
Cell wall, cytoplasmic membrane, mitochondrion, nuclear membrane, nucleus, ribosomes, cytoplasm
ALL Cells share…. (4)
- cytoplasmic (cell) membrane
-cytoplasm
-ribosomes
double stranded DNA genomes
Cytoplasm
aqueous mixture of macromolecules, ions, and ribosomes
Coccus (cocci)
round, sperical
Rod (bacilli)
rod shaped
Spirillum (spirilla)
looks like a small bannana
Spirochetes
zig zag
- a shape and a phylum
Budding and appendaged
Stalk and hypha
-big center with projections coming out of center
Filamentous
thin filaments
Sheathed bacteria
filament surrounding with bulk center
- some sheaths/stalks are made of polysaccharides; others are made of iron oxides (e.g iron oxidizing bacteria)
