What is horizontal gene transfer
it is the passing of genetic information between two mature cells. (instead of vertical gene transfer, which is from parent to offspring)
Do prokaryotes have a nucleus
nope, they do have what is called a nucleoid. Which is just where the prokaryote has its genetic material, but it is not confined in a membrane
What are plasmids
small segments of DNA in prokaryotes that Replicate independently of the prokaryotic chromosome
Are plasmids essential for the life of the prokaryote
no they are not essential for normal growth, reproduction, and metabolism
although plasmids aren’t essential, how can they be beneficial to the prokaryote
they contain factors that help it survive
what types of factors can be found on vectors (4)
- Fertility Factors (genes for conjugation)
- Resistance Factors (against antimicrobials and metals)
- Bacteriocin Factors (toxins against similar organisms)
- Virulence factors (virulence factors against host)
Can plasmids integrate themselves into the bacterial chromosomes
yep
What are the three ways in which bacteria can transfer genetic information
- Transformation
- Transduction
- Conjugation
What is transformation (bacterial genetic information transfer)
when a bacterial cell picks up free DNA fragments and incorporates them into their chromosome
What is Transduction (bacterial genetic information transfer)
When an empty viral phage coat gets loaded with bacterial DNA, then injects it into another cell
What is conjugation
When a F+ (fertility plasmid) Cell uses a conjugation pilus to connect to another cell, then it transfers it DNA through the hollow conjugation pili
what was the finding from Griffiths experiment with rough and smooth Streptococcus Pneumoniae cells
that the new, non-virulent strain, would pick up and use the virulent DNA from the dead cells and use it to kill the mice . Proved transformation happens
What happens when an F+ cell successfully conjugates with an F- cell
the Fertility plasmid will be transferred to the F- cell, making it F+
What is an HFR cell
a cell with High Frequency of Recombination, which is a cell which has had the Fertility plasmid become integrated into its chromosome
What happens typically when an HFR conjugates with an F- cell
it only transfers a portion of the fertility plasmid, along with part of its chromosome. so the F- cell has more DNA, but not a complete Fertility plasmid so it is still F-, and is also F’
What are transposons
sequences in the prokaryotic chromosome that can break out, replicate, then reinsert themselves into different places on the chromosome.
can transposons jump to plasmids
yep
What is VRE
vancomycin resistant Enterococcus
what is MRSA
methicilin resistant Staphylococcus aureus
What is a silent mutation
a swapped out base in DNA that doesn’t lead to a change in the corresponding amino acid
What is a missense mutation
a swapped out base in DNA that causes a change in the corresponding amino acid
what is a nonsense mutation
a swapped out base in DNA that leads to an early stop codon
What is a frameshift mutation
either an insertion or deletion of a base pair in DNA, this causes all of the following amino acids to be altered due to the way it causes the reading frame to be shifted
What does UV light do to DNA
causes a thymine dimer, which is the creation of bonds between two thymines on the same strand of DNA, causing a bubble of sorts between the two strands
How is Recombinant DNA technology done
you get your gene of interest, and cut it out of its DNA, and place it into a plasmid, put that plasmid into bacteria, and have the bacteria produce the protein of choice
How does PCR work
you put primers in with the DNA you are running, heat it up so the double stranded DNA separates, then cool it down so the primer attaches to a single strand of DNA, and let the transcription machinery create a copy strand. then repeat over and over again.
What is the end goal of all microbial metabolism
to reproduce the organism
what is microbial growth
an increase in a population of microbes, rather than the microbes increasing in size
What are the necessary elements for microbes
carbon, oxygen, nitrogen, and hydrogen
What is an autotroph
an organism that has the ability to get its carbon from the CO2 in the air (green plants)
What is a heterotroph
an organism that gets it carbon from consuming carbs, proteins, fatty acids, and amino acids.
What are chemotrophs
organisms that get their energy from redox reactions with organic and inorganic material
What are phototrophs
organisms that get their energy from light
What are examples of photoautotrophs
plants, algae, cyanobacteria
what are examples of chemoautotrophs
only prokaryotes
hydrogen, sulfur, and nitrifying bacteria
What are some examples of photoheterotrophs
only prokaryotes
green and purple nonsulfur bacteria
What are chemoheterotrophs
most animals, fungi, protozoa, many bacteria
What are obligate aerobes
organisms that need oxygen to survive
what are obligate anaerobes
organisms that are killed by oxygen
How does oxygen kill obligate anaerobes
O2 isn’t toxic, but the Reactive Oxygen Species are, and obligate anaerobes don’t have the machinery to neutralize the Reactive oxygen species
What are facultative aerobes
organisms that can live without oxygen, but do better with oxygen
What are aerotolerant aerobes
organisms that don’t need oxygen, but aren’t affected by it at all (not for better or for worse)
What are microaerophiles
organisms that require oxygen, but at lower partial pressures. can’t live without it, or with too much of it
What would you expect to see with a strict aerobe in a thioglycollate medium
only growth in the upper oxygen rich area
What would you expect to see with a strict anaerobe in a thioglycollate medium
only growth in the lower oxygen depleted area
What would you expect to see with a facultative aerobe in a thioglycollate medium
growth throughout the medium, but more in the oxygen rich area
What would you expect to see with a microaerophile in a thioglycollate medium
most of the growth, somewhere in the oxygen rich area, but not at the very top
What would you expect to see with a aerotolerant anaerobe in a thioglycollate medium
equal growth throughout the medium
is nitrogen required by microbes
yes, because it is needed in proteins and nucleotides
are bacteria essential for life on earth when it comes to the nitrogen we need
yes, because it is bacteria that fixes the nitrogen gas to ammonia so that we get the nitrogen we can use.
How does temperature affect growth of microbes
there is a Minimum temperature at which membranes gel and no growing can occur, from that point activity increases with increasing temperature until it reaches an Optimum activity point. with any more temperature you begin to destroy the organism.
What do you call an organism that grows best in cold temperatures
psychrophile
what do you call an organism that grows best in moderate temperatures
mesophile
what do you call an organism that grows best in hot temperatures
thermophiles
what do you call an organism that grows in extremely hot temperatures
hyperthermophiles
What pH do most bacteria and protozoa prefer
neutral pH (6.5 to 7.5) neutrophiles
what do you call bacteria that prefer a low pH level
acidophiles
what do you call bacteria that prefer a high pH level
alkalinophiles
do most bacteria need water
yes, most die in the absence of water (endospores and cysts are the exception)
What happens to cells (without walls) when placed in a hypotonic solution
water runs into them, and causes them to lyse
what happens to cells placed in a hypertonic solution
the cells will shrivel up
what are halophiles
organisms that can grow in hypertonic solutions (salty)
what are obligate halophiles
organisms that grow in up to 30% salt
what are facultative halophiles
organisms that can tolerate high salt concentrations
What are oganisms that live under extreme pressure called
barophiles
what do you call organisms that live in high CO2 concentrations
Capnophiles
What is an anatagonistic relationship (parasitism)
one organisms benefits, the other is harmed
what is a synergistic relationship (mutualism)
both organisms benefit
what is a symbiotic relationship
the organisms are interdependent
What is commensalism
one organism benefits, the other is indifferent
What is a biofilm
complex relationships among numerous different organisms
What is the CFU when creating cultures of cells
the CFU is the colony forming unit, or the progenitor (parent) of the entire colony
What are streak plates and pour plates used for?
isolating colonies
How does blood agar work as a differential medium
different specimen perform different types of hemolysis on the blood agar, which results in different looking cultures
what is a-hemolysis
partial RBC destruction
what is b-hemolysis
complete RBC destruction
what is y-hemolysis
no RBC destruction
What are the three ways to preserve cultures
Refrigeration
deep-freezing
lyophilization
is bacterial growth log linear
yes
What are the four phases of microbial growth
- Lag phase (not much growth)
- Log phase (exponential growth)
- stationary phase (no growth, but at max growth level)
- Death Phase (decline)
What is the equation for bacterial growth
N(t) = N(o) (2^n) n=t/g n= number of replications t = time g = generational time
How do bacterial multiply
binary fission
What are the four direct methods for measuring microbial growth
- Viable plate counts
- membrane filtration
- microscopic counts
- electronic counters
how is a viable plate count performed
you make plates with increasing diluted (10x less concentrated each step) samples of the culture, then once you can get to a countable number of colonies you can estimate how many colonies were in the original concentration
how is microscopic counting performed
you spread out colonies on a grid, then choose one specific square, magnify it and count the colonies. Then you can multiply the number of colonies in that square by the total number of squares
What are the three methods for indirect measuring of microbial growth
metabolic activity
dry weight
turbidity
What is turbidity and how does it measure microbial growth
you shoot light through a control tube without growth in it and measure the light that gets through, then you do the same to a tube with growth in it and see how much light has been reflected.
how does turbidity correlate with concentration
the relationship is log linear, the higher the concentration the lower the transmittance
