Lecture 1- what is microbiology? Flashcards
what is microbiology?
the study of organisms too small to be seen with the naked eye
why is microbiology so important? 5
-microbes are the oldest form of life
-largest mass of living material on earth
-biogeochemical cycles
-live in places unsuitable for other organisms
-microbes are an important factor of the ecosystem
what are the 7 things all cells have in common? prokaryotes eukaryotes
cytoplasmic membrane
cytoplasm
genetic material
genome
chromosome
plasmid
ribosomes
genetic material function
all cells store their genetic information as DNA, the information is divided into genes
what is a genome
a cells full complement of genes (the arrangement of genes tells us lots about the cell)
what is a plasmid
a piece of DNA that carries non-essential genes (ex. genes for antibiotic resistance)
ribosome function
site of protein synthesis
what is protein synthesis?
process of creating protein molecules
how does protein synthesis work?
starts in the nucleus:
DNA –> transcription –> RNA –> splicing –> mRNA
mRNA gets exported to the cytoplasm:
mRNA –> translation –> mRNA decoded –> folds up –> protein!!!
what are the 3 main types of “microbes”?
eukaryotes
prokaryotes
viruses (not a microbe)
what are 5 unique things about eukaryotes? what is the internal structure like? how do they divide? what do they use for energy?
membrane bound nucleus
membrane bound organelles
complex internal organization
division by mitosis and meiosis
almost all eukaryotic cells can use glucose for energy and can store some form of glucose for energy
what are 2 examples of eukaryotes?
protists
fungi
what are protists? are they multicellular or unicellular?
unicellular or multicellular without differentiation into tissues
what are 3 examples of protists?
protozoa: animal- like microorganism
algae: photosynthetic plant- like microorganisms
slime molds and water molds: filaments
what are characteristics of fungi?
unicellular (yeasts)
filamentous (molds)
multi- cellular (mushrooms)
what are 5 unique things about prokaryotes? how do they divide? multi or unicellular? what is the internal structure like?
no membrane bound nucleus or organelles
generally smaller
simple internal structure
divide by binary fission
most are unicellular
what are 2 examples of prokaryotes?
bacteria
archaea
what are 4 unique things about viruses?
acellular infectious particles
extremely small (smaller than prokaryotes)
obligate intracellular parasites
lacks independent metabolism, therefore, dependent on the host metabolism
viruses lack an independent metabolism, what does that mean?
no ribosomes or ribosomal RNA
cant be classified with other microbes because they have no cells of their own
what is different about a prokaryotic cell compared to a eukaryotic cell?
no nucleus
no mitochondria
no endoplasmic reticulum
in practice, what should species of bacteria and archaea have? (3)
most characteristics in common
greater than 97% sequence similarity in the 16S RNA gene
high degree of genome similarity (DNA-DNA hybridization)
what are the 3 domains of life that all organisms get classified into?
bacteria
archaea
eukarya
how do we classify what domain an organism goes into?
we look at genetic differences rather than morphological (appearance) differences
what is more diverse; microorganisms or plants and animals?
microorganisms! (some are even visible to the naked eye)
what ribosomes do prokaryotes have?
70S ribosomes and 16S subunit rRNA genes
what ribosomes do eukaryotes have?
80S ribosomes and 18S subunit rRNA genes
rRNA changes slowly overtime, what are the 4 basic steps to sequencing rRNA genes?
- DNA is collected from a pure culture
- the subunit rRNA gene is amplified using the polymerase chain reaction
- the gene is sequenced
- sequence is aligned with sequences from other organisms (the number of differences is used to calculate evolutionary distance)
what is the polymerase chain reaction?
its a technique used to synthesize many identical copies of a short sequence of DNA
what is more closely related to archaea? bacteria or eukarya
eukarya
what does anaerobic mean?
any organism that does not require molecular oxygen for growth
how did anaerobic organisms change the world?
photosynthetic bacteria gave off oxygen and therefore oxygenated the world about 2 billion years ago, this allowed for the evolution of modern eukaryotic microorganisms
robert hooke birth and death year
1635- 1703
what did robert hooke do?
the first to describe microbes
used a compound microscope (magnification up to 30x)to observe cells in cork trees, mold filaments (1st microbe) and the beginning of cell theory
what was the cell theory that robert hooke came up with?
all living things are composed of cells
antoni van leeuwenhoek birth and death year
1632- 1723
what did antoni van leeuwenhoek do?
built microscopes that magnified by 50- 300x
observed single celled microorganisms and called them “animalcules”, this was the first discovery of bacteria
louis pasteur birth and death year
1822- 1895
what did louis pasteur study?
wine and beer production
what did louis pasteur discover about wine and beer?
yeasts convert sugar into alcohol in the absence of oxygen (fermentation)
bacteria can sour wine by converting alcohols to acid
what did louis pasteur do to kill unwanted bacteria?
invented pasteurization and spontaneous generation
how does pasteurization work?
non-sterile liquid poured into flask –> make swan neck on flask with flame –> liquid sterilized
why did pasteur bend the neck of the flask?
so that dust and microbes would get caught in bend and not enter the sterile solution, thus the solution would remain sterile indefinitely
how could the solution become non-sterile using pasteurization?
if the flask tips over and the solution touches the microorganisms
what kind of infusions did pasteur prepare in these swan- necked flasks?
meat infusions
what methods did pasteurization lead to the development of?
methods for controlling the growth of microorganisms (aseptic technique)
robert koch birth and death year
1843- 1910
what did robert koch study?
anthrax disease
what is the process on how koch studied anthrax?
- isolated the bacteria from the diseased animal
- injected healthy animals with the bacterium
- animals became ill with anthrax
- re-isolated B. anthracis from the test subjects
- proved it was identical
- established a set of criteria for relating a specific microbe to a disease
what is meant by kochs postulates?
general guidelines to identify infectious microbes that could be detected with the available methods and that were demonstrably alive
what is normally in a petri dish?
nutrient broth medium solidified with 1.5% agar
why was agar chosen as a substance in a petri dish?
melts at ~97C and solidifies at ~43C
cant be degraded by most microorganisms
what are 3 techniques to isolate pure cultures?
streak plate technique
spread plate technique
pour plate techniques
how does the streak plate technique work? (5)
- heat inoculating loop till its white
- let cool (now its sterile)
- streak sample across the plate (it will get more and more diluted with each)
- plate is incubated
- individual cells grow to form colonies
what are colonies?
a mass of cells (ideally arose from one single cell)
colonies can be used to create a pure culture
how does the spread plate technique work?
- sample is diluted before plating
- diluted sample can be spread over the surface of the plate with a sterile spreader
how does the pour technique work?
- mixed with molten (soft) agar ~45C
- swirl to mix
what is the big difference between the spread plate technique and the pour techniques results?
A spread-plate assay produces a plate with colonies distributed across the agar surface
pour plate assay produces a mixture of colonies embedded within the agar layer and colonies presenting at the agar surface
how many colonies need to be on the petri plate for it to be up to standards?
30- 300 colonies
if we have less than 30 colonies what does that mean?
not statistically significant
if we have more than 300 colonies what does that mean?
colonies grow into each other.. inaccurate counts
