Lecture 1 Flashcards
Three places bacteria is found?
Oceans, soils, deep surface sediments
How many bacteria are there on the earth?
4-6E30 (more than the number of stars in the sky)
Prochlorococcus Marinus
- Responsible of Carbon and O2 production!
- Most numerous organism on earth.
- Found in the ocean
- Uses photosynthesis
How many bacteria are on/in humans?
10 bacteria for every one human cell!
Why is it hard to estimate how many bacteria are on earth and the diversity of the bacteria?
Because it is difficult to colonize the bacteria and then it is hard to see what type of bacteria it is when we do colonize it
What is the microbiome?
Collection of all the microbial species in a particular location
What do the core genes represent in the DNA of a bacteria?
The genes which define the species and relatedness
What do the other genes in the genome of a bacteria represent?
Defining properties of a particular strain of bacteria
How does genetic diversity exceed species diversity?
Because the “other genes” make each strain within a SPECIES unique. This is how we get different strains of all bacteria (like the different strains of E.Coli we used in lab–differ in their “other genes” same in their “core genes”
What kind of genetic diversity to specialized bacteria have?
Very low genetic diversity meaning they have a large number of core genes and few “other genes”
What is a symbiotic relationship?
A relationship in which two organisms live together (example is humans and bacteria)
Clostridium difficile infections:
An infection caused by prolonged use of antibiotics. It involves diarrhea, abdominal pain, dehydration, and fever. Treated with antibiotics
How does early exposure to germs affect humans?
Allows for resistance to germs leading to prevention of infection later in life
What does exposure to house dust (from dogs) do for you?
Protects against allergens by reducing cytokine Th2, producing fewer activated T cells against allergens
What is the deal with the obese twin/lean twin microbiome study?
Put microbiome of each twin into different mice and saw that the mouse that got the microbiome from the obese twin also became obese!
How can bacteria be used to help against autism?
Treating with bacillus fragilis has been shown to decrease anxiety and increase sociability. It works by improving the epithiliat barrier and reducing the leakage of GI metabolites so that serum metabolites can be restored!
What are the TWO main problems with working with bacteria?
1) enormous number of bacteria in each sample
2) Enormous diversity (no two samples the same)
What is a pure culture?
A culture in which all the bacteria are the same
What are the four koch’s postulates associated with identifying infectious organisms?
1) Org should always be present in animals with disease
2) Should be grown in pure culture
3) When injected into healthy animal, should cause disease
4) should be reisolated from experimentally infected animal
What do we use serial dilution for?
To get a small amount of cells/ml so that when plated, you can isolate a pure colony
what is a colony?
clones of a single cell (all bacteria in colony are identical)
How is morphology used?
To estimate the diversity in a sample by looking at colony appearance
What is the problem with serial dilutions?
They take forever and it is hard to get the right number of colonies on a plate (usually too many or too few)
What is streaking out used for?
To get isolated colonies quickly
What is the problem with using colonies as a source of pure cultures?
we can’t plate all bacteria and some bacteria don’t form colonies, colonies also spread and overlap eachother
Bacillus Subtillis
Does not form colonies but instead a spider web effect known as dendritic growth
Proteus Mirabillis
A bacteria which swarms outward as nutrients become scarce
What is the problem with pure culture?
1) It leads to domestication
2) Bacteria communicate and interact with friends so isolation makes it difficult to see the true nature of said bactera
What is domestication
The loss of phenotypes valuable in natural environment because the bacteria is being grown in controlled enviroment
What is planktonical growth?
Bacteria grown in broth similar to the content of the ocean
Periodontal Disease:
Infection of gums cause by porphyromonas gingivalis caused by interaction with normal flora
What does the normal flora in mouth do?
Keeps gums inflammed so that infectious bacteria can not get in
P. Gingivalis: how does it work against the normal flora?
It alters the inflammatory response of normal flora so it can infect the gums
What two components do all bacteria need to grow?
1 source of energy
2 source of reduced carbon
How is energy derived in all organisms?
Through the release of energy via an electron gradient
3 sources of electrons for energy?
1) Organic compounds (glucose)
2) Inorganic compounds (nitrites)
3) Light activated compounds (chlorophylls)
Which 2 ways do organisms get reduced carbon?
From inorganic carbon or from reduced carbon
Heterotrophs
Get carbon from organic
Autotrophs
From inorganic compounds
Chemoheterotrophs
use organic compounds for energy and for carbon source
Photoautotrophs
energy-light
carbon-CO2
What type of bacteria are cyanobacteria?
photoautotrophs(obligate aerobes)
What are animals?
Chemoheterotrophs which use organic compounds for energy and organic compounds for carbon
What are plants?
Photoautotrophs
