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Final

BIOL240 Study Guide - Final Guide: Replica Plating, Root Nodule, Nonsense Mutation


Department
Biology
Course Code
BIOL240
Professor
Trevor Charles
Study Guide
Final

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Microbiology notes
Why are bacteria important?
Impact almost al bio in the world
Influence the earth’s development
Make up over 50
5 of the earth’s biomass
Microbiology is the science of microorganisms (these are organisms that can only be seen with a
microscope).
Microbes(microorganisms) can be divided in to two
Prokaryotes
Eukaryotes
bacteria
Algae, fungi and protozoa
Achaea
Bacteria interact with different organisms e.g. root nodule in leguminous plants
What makes a cell alive
Cells have metabolism, this metabolism then results in growth, cells differentiate, they communicate,
they are motile and they evolve
Reasons for studying microbiology
Microbes were the first life on earth
Created the biosphere that allows macro organisms to evolve
Multicellular organisms evolved from micro organisms
Over 50% of the earth’s biomass
Helps in the study of life
Machine and coding functions of the cell
Machine functions : energy production, metabolism, enzymes
Coding functions: DNA replication and translation to form proteins
These two functions are interrelated and they both result in growth
Applications of microbiology
Mining : can act on the ore of copper to release pure copper
Agriculture: E.g., root nodules, plants that contain bacteria in their nodules do not need fertilizer
Health and Medicine
In animals cellulose digesting bacteria break down the grass in their bellies
Food industries: production of cheese, wine, etc
Bio fuels: corn to ethanol {good fuel}
Bio remediation: using bacteria to clean up toxic pollutants or oil spills
Biotechnology; production of drugs in pharmaceuticals.
Better sanitation and the production of antibiotics helped reduce death caused by infectious diseases
Where do microorganisms come from? Spontaneous generation was the first theory of
microorganisms because of food spoilage.
Louis Pasteur disproved the theory of spontaneous generation. With his experiment.
Procedure

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Chicken broth was added to a flash with a long neck, the neck was stretched, and the broth was
heated repeatedly and kept for a very long period there was no sign of microbes. Then after some
time the flask is tipped so that the liquid touched the neck of the flask and then after some time the
Broth spoiled
Koch’s postulates (germ theory of disease)
Koch carried out an experiment to find out the causative agent of some diseases. Some diseased rats
were tested and their blood had both red blood cells and bacterial cells this observations lead to:
1. The pathogenic organism should be present in all disease cases and absent from healthy animals
2. It should be able to grow in pure culture
3. The cells from the pure grown culture should be able to infect a healthy animal
4. If the blood is removed from the diseased animals, it should contain the same pathogen
This lead to the following conclusions
Specific organisms cause specific diseases; Koch’s postulates can also be applied to other organisms
Cell structure
Prokaryotes
do not have a nucleus
DNA not surrounded by a nuclear membrane
Eukaryotes
DNA is in a nuclear membrane
Also, have organelles that have their own DNA
Are kimeric organisms and probably arose from an archaeal organism.
Three domains of life
Sequencing of the 16s (prokaryotes) or 18s (eukaryotes) ribosomal rna gene shows how closely
related two organisms are. This is used to create the phylogenetic tree. The three domains of life are
Bacteria
Archaea
Eukarya
Physiological diversity of microorganisms
for a cell to grow it has to take energy and carbon compounds from the environment.
Two main source of energy are chemicals and light
Chemotrophs get their carbon from chemicals e.g. chemorganotroph, chemolithotroph, and photo
trophs
Only archaeal are chemolithotrophs
Heterotroph(humans require an external carbon source) and autotroph(plants make their own
organic compounds)
Most archaeal organisms are extremeophiles
.Bio 140 notes two after mid term

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Terminologies in microbiology: Microbiologists are strict with their terminologies in order to
distinguish between mutants, strains and mutations. The first organisms used to develop a genetic
system were salmonella and e-coli.
A mutant is a strain carrying a mutation
A mutation is the change that occur within a gene to make another gene or allele
This usually involves gain of function, loss of function, or change of function.
Genotype is a description of all alleles within an organism, it is usually related to the wild type( the
non mutated type)
Phenotype of an organisms are the observable properties of the strain that contains the mutation
His-(this is the phenotype) hisC- or hisC- ( and it is the genotype)
The wild type of E-coli is K-12
Selectable phenotype: the bacteria can be placed in a medium so that only that phenotype can grow
in that medium. His+ is a selectable phenotype because they can grow in a medium that does not
have histidine. His- is a screen able phenotype, but it is extraneous. A selectable medium allows
mutation that occurs in low frequency to be detected.
Mutants arise spontaneously, mostly during replication. DNA polymerase is not a perfect enzyme.
Replica plating is used to isolate mutants, this is done by treating the wild type strains with
mutagens, this is plate is diluted and plated for single colonies and then it is grown on a complex
medium; this plate is called the master plate. The master plate is then pressed on a sterile velvet
placed on a wooden cylinder; this allows some cells to be transferred unto it. Some cells are
transferred to a minimal medium and some are transferred to a complex medium. All the cells would
grow in the complex media but not all of them would grow in the minimal media these are possible
auxotrophs.
replica plating
Types of mutation:
Auxotroph: can’t produce a certain nutrient
Non motile can’t make their flagella
Pigmentless: have diff colour from the wild type
Temperature-sensitive: cannot grow at temperatures that usually support growth
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