Lecture Final Flashcards
Why is the incidences of food poisoning increasing today even though there is more sterile techniques?
More reported cases, stronger bacteria
What is the infective dose?
The number if bacteria required to cause an illness
What is the term for inflammation of the stomach, small intestines, or large intestines?
Gastroenteritis
What is one ya to treat E. Coli?
Clostridium difficile
What is a differential medium?
Allows all growth but causes a color changes where target bacteria is present
What is a selective medium?
Only allows the growth of a specific strain of organisms
What are the properties of MSA (mannitol salt agar)?
Selective and differential medium
Salt only allows halophiles to grow
Some use them manninol to produce acid-changes pH
What strain of E. Coli can cause kidney failure in small children?
E. Coli 0157:H7
What does HAACP do?
Increases food safety in production lines by aiming to prevent contamination rather than detect contamination
Bacteria is ubiquitous, true or false?1
True, it can never be completely eliminated
What does HACCP stand for?
Hazard analysis critical control points
What is the effective dose of E. Coli 0157:H7?
50 organisms
When was the sanitary revolution?
Early 1900s
What are the two types of medium used to identify the presence of a specific pathogen?
Selective medium, and differential medium
What are steps that are crucial to food safety?
Critical control points
What are critical control points?
Steps that are crucial to food safety
What is a DNA probe
Short strands of DNA that are complementary to the genes present in the microbe
What is hybridization?
The annealing of complementary strands
What must be done before probes are added
Microbe cells must be lysed to release their DNA
What is the gene track system used for?
Detecting pathogens in food samples
How long does do gene trak system take to compete?
24-48 hours
What does NaOH do?
Separates the DNA from two strands into one (like helicase)
What is done after probes are added?
A dipstick with a poly T sequence is added
What does the poly T sequence do if bacteria is present?
Removes DNA strands that have hybridized to both probes
What does the ploy T sequence do if no bacteria is present?
Captures unhybridized probes
What are the advantages to the Gene Trak System?
Very specific and reduces The time requires for microbe identification
What are there disadvantages to Th Gene Trak System?
Requires a lot of time for enrichment and can provide false positives
What does real time PCR do?
Combines amplification and probing in one process.
What does the quencher flourophone do .
Reduces flouroscence from the reporter when the two are in close proximity
What are the two types of flouroscence molecules attached to e probes in TaqMan PCR?
Quencher and reporter
What are the problems with PCR?
Does not distinguish between live an d dead cells
What does a microarray do?
A technique that allows for the simultaneous detection of expression of thousands of gene
What is cDNA and how is it made?
DNA with the introns- copied directly from mRNA
How are antibodies produced?
By the immune system
What does IgG stand for?
Immoglobulin
What are antibodies that are obtained from different B cells
Polyclonal antibodies
What are antibodies produced from a cloned hybrid cell?
Monoclonal antibodies
What is a hybridoma?
A B cell fused with a myeloma cell
What happens to the B cells which remain unfused?
They die
The rate of ________________ affects whether or not transcription is completed.
The rate of translation affects whether or not transcription is completed.
What are there three levels of regulation of amino acid production in E. coli?
- Regulation of enzyme activity through feedback inhibition
- Regulation of transcription
- Attenuation
When does attenuation regulate?
During transcription
How many regions does the mRNA transcript contain?
4
What happened if the ribosome incorporates trp at section 1 quickly, what happens?
Sections 3 and 4 form a loop and stop transcription
What happens if the ribosome stalls at section 1?
Section 3 will bind with section 2 and allow transcription to complete
Why can’t LAB be be transformed with a pUC plasmid .
- Because in the pUC plasmid the ampicillin gene cannot be removed and is growing continually in the presence of the ampR gene. This is not allowed by the FDA
- We do not want an ori site
What are stereoisomers?
Molecules that have the same molecular formula and sequence of bonded atoms, but differ in their 3D orientation of atoms.
What happens if an excess of proline is present?
Transcription will shut off
What are some reasons for the overproduction of amino acids?
- Flavor enhancers
- Supplements
- Sweeteners
- Parenteral nutrition
- Industry uses
- Pharmaceuticals
Why don’t researchers synthetically create amino acids?
Stereoisomers
Why don’t microbes produce excess amounts of amino acids?
Waste of energy
what is substantial equvalence?
d
What is the ci region on the pEM76:ci plasmid?
Is it is the gene we are targeting
What does attenuation do?
Controls the rate translation and can either slow it down or speed it up depending on the amount of tRNA
What color does S. Marcescens turn on agar?
Red
How does S. Marsescens regulate amino acid production?
Feedback inhibition
Why does E. Coli need three levels of regulation while S. Marsescens only uses one?
- Where they grow
2. Environments each must adapt to
What are osmoprotectants?
Small molecules that help organisms survive extreme osmotic stress
Why is S. Marsescens grown in the presence of high salt concentrations?
To make the bacteria produce excess proline in reeder to avoid dehydration
What is an isotonic solution?
Equal pressure
What is an hypotonic solution?
Higher pressure outside than inside. Water moves into the cell
What is hydroponic solutions?
Higher pressure inside the cell than outside. Water moves out of the cell
What do the bacteria cells do under conditions of low oxygen?
Produce more glut amine
What type of cycle do many bacteria use under aerobic conditions?
TCA cycle
No is aspartame produced?
Fumarate + ammonia + asparate =asparate
why are the benefits to making aspartate chemically?
- Fumarate and ammonia are cheap
- Purification of aspartate is easy
- No growth media
What’s are osmoprotectants and how do thy work?
Overproduce an amino acid in order to equal out osmotic pressure in and out of cell to prevent dehydration
What conditions are required to overproduce glutamine from C. Glutamicium
Low oxygen and low biotin levels while growing colony on molasses
what is epigenetics?
the study of changes in phenotypes or gene expression caused by factors other than the DNA
what is genetic imprinting?
the genetic phenomenon in which certain genes are expressed in a parent-of-origin-specific manner
what is maternal imprinting?
the gene from the mom is inactive
what is paternal imprinting?
the gene derived from the dad is inactive
if is gene is only expressed if inherited from the father, the gene is ___________________
if is gene is only expressed if inherited from the father, the gene is maternally imprinted
what is monoallelic inheritance?
when genes are expressed as if there is only one copy of the gene present even though there are two
what does DNA methylation do?
adds a methyl group to the DNA and reduces gene expression
ICR stands for…
imprinting coding region
what does the ICR site do?
its the binding site for a protein which inhibits imprinting
what is the protein which binds to the ICR site?
CTCF
what happens when CTFC binds to the ICR site in maternal germ cells?
it blocks igf2 leaving H19 on
what happens when CTFC binds to the ICR site in paternal germ cells?
CTFC cannot bind to the ICR site in paternal germ cells
what happens to the ICR site in males?
it becomes methylated, inhibiting CTFC from binding
what does the methylation of the ICR site do to the igf2 and H19 sites?
igf2 is on, H19 is off
what was the difference between the yellow and brown mice in the example?
In yellow mice, the agouti gene is unmethylated and turn on all the time. In brown mice, the agouti gene in completely methylated and shut down.
how did the amount of BPA fed to a pregnant mouse relate to the offspring?
higher increase of yellow mice, DNA methylation was decreased resulting in high health risks.
what is heterochromation?
domains of the chromosome that are bundled to be highly condensed. No expression
what is euchromatin?
domains of the chromosomes that are less condesned. Expression.
what is genetic silencing?
a process which genes are turned off due to a position effect that depends on the neighborhood in which the gene is located
what is position effect variegation (PEV)?
when heterochromatin from the centromere region spreads into the euchromatin region and silences the white eyed gene
how are calico cats made?
through dosage compensation
what is the term used to describe inactive chromosomes?
Barr body
what is a Barr body?
inactive chromosomes
how is dosage compensation achieved in mammals?
through X-inactivation
What can protect bacterial DNA from restriction enzymes?
methylation
What are starter cultures of LAB used for?
inoculating milk
What do calcium chelators do?
suppress the growth of bacteriophages
What are starter cultures sometimes grown in the presence of to prevent the growth of pages?
calcium chelators
what are three methods used to prevent the growth of phages?
Phage resistant strains of LAB Phage inhibitory media Recombinant LAB
How Is there ampicillin resistance gene removed for the pEM76:cl plasmid?
the B-recombinase gene from PEM68
what region is the pEM76:cI plasmid missing and why?
The original site because it is being inserted into a chromosome and we do not want this plasmid to replicate independently.
what are the main differences between the PBR322R plasmid and pUC plasmid?
pUC has better ori site pUC has MCS site instead of BamH1 pUC has lac-z gene instead of tetracycline gene
what does BIM stand for?
Bacteriophage-insensitive mutants
what percentage of our DNA is actually coding?
less than 5%
what are transposable elements (TEs)?
sequences of DNA that move from one location in the genome to another
who discovered transposons?
Barbara McClintock
what were the two factors that McClintock noticed in Indian corn?
the Ds region and Ac region
what are autonomous elements?
segments that require no other elements for their mobility
what are non-autonomous elements?
segments of DNA that do not encode the functions necessary for their own movement
what causes spotted kernels in corn?
autonomous regions, or non-autonomous regions with with an activator
what does transposase do?
allows non-autonomous sequences to move. It is the activator.
what’s a composite transposon?
they contain a variety of genes that reside between two nearly identical IS sequences that are orientated in opposite direction
what is an insertion sequence (IS)?
segments of bacteria DNA that can move from one position on a chromosome to a different position on the same chromosome or a different chromosome.
what are simple transposons?
regions that contain several genes which are flanked by IR sequences.
what are the two mechanisms of transposons?
replicative-makes a copy and stays sending the copy elsewhere
conservative-transposon completely moves from one site to another
what are the two classes of transposons in eukaryotes?
tetrotransposons, and DNA transposons
what are the three genes of retroviruses?
gag, pol, and env
what is hybrid dysgenesis?
refers to the high rate of mutation in germ cells when wild type males are mated with laboratory strain females
m strain females + p strain males = ?
sterile flies with frequent mutations
p strain females + m strain males = ?
normal flies
what is a C-value?
the amount of DNA content in a genome
what are the two transposons in humans?
1) long interspread elements (LINES’s)-move like a retrotransposon
2) short interspersed elements (SINE’s)-non-autonomous LINE’s that do not encode a reverse transcriptase
