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Lecture Set 5 Flashcards

1
Q

can microbes eat human food?

A

-yes!
-human food are rich in organic matter and contain the needed nutrients for most microbes (CHOPKNSCaFeMg)

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2
Q

what determines which foods are more favourable for microbial growth?

A

-perishable vs non perishable
-perishable has higher moisture which most microbes prefer
-pH
-salt concentration
-storage conditions (temperature)

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3
Q

is food considered sterile?

A

-NO

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4
Q

what is food spoilage?

A

-any change in appearance, smell, or taste of a food product that makes it unacceptable to the consumer
-does not have to be due to microbial growth

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5
Q

what is the temperature class of most food spoilage microbes?

A

-psychotolerant

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6
Q

are there any sole microbial contributors to food spoilage?

A

-no, there is a wide range of microbes responsible

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7
Q

what is the goal of food preservation?

A

-to slow or stop (control) the growth of microbes that spoil food or can cause food borne illness

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8
Q

what are the major methods of food preservation?

A

-temperature (heating or storage temps)
-acidity (pH) (pickling/fermentation)
-moisture level (high moisture = higher microbial concerns, fungi can grow in dryer conditions)
-treatment with radiation or chemicals

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9
Q

what is phage-based biocontrol?

A

-uses of bacteriophages to control bacterial growth in different settings (food safety)
-lyses target bacteria

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10
Q

what are different brands of phage-based biocontrol?

A

-listshield or listex (control of listeria monocytogenes)
-ecoshield (control of E.coli O157:H7)
-salmofresh (control of salmonella)

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11
Q

what is the purpose of canned products?

A

-create an anoxic environment to limit bacteria
-no obligate aerobes or microaerophiles

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12
Q

what is dangerous bacteria that can be a concern with the canning of certain foods?

A

-endospore-forming clostridium bacteria
-it is anaerobic so canning can provide an ideal environment for it
-clostridium botulinum is the cause of botulism

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13
Q

why should you not eat a food with a swelled can?

A

-sign of gas being produced which indicates that microbial growth is occurring

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14
Q

what can botulinum toxins be used for?

A

-to treat chronic pain
-low dose injections of dilute botox (incredibily potent) relaxes affected tissues by causing flaccid paralysis (permanent muscle relaxation)
-does so by blocking the release of acetylcholine which is what induces muscle contraction

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15
Q

what is food poisoning?

A

-also called food intoxication
-caused by ingesting foods containing microbial toxins
-the pathogen itself is not present

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16
Q

what is food infection?

A

-ingesting foods containing sufficient numbers of viable pathogens which results in disease
-no toxin is present

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17
Q

what is food borne illness? how does it distinguish from food infection and food poisoning?

A

-a general term for any illness caused by eating contaminated food
-not specifically tied to microbes
-can include both food infection and food poisoning under the umbrella

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18
Q

what are the 5 major foodborne pathogens in canada?

A

-norovirus (leading cause of illness)
-listeria (leading deaths)
-salmonella
-E.coli O157
-campylobacter

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19
Q

what is listeria monocytogenes?

A

-psychotropic bacterium
-invades cells of the intestinal epithelium
-causes listeriosis (infection)
-enhanced issue because it can grow both in the body and under refrigerated conditions

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20
Q

what is the mechanism (virulence factor) that listeria monocytogenes uses?

A

-phagocytosizes into the cell (phagosome forms around it)
-degrades the phagosome and releases into the cytoplasm
-actin surrounds the listeria and assists in its movement
-actin propels it into the neighbouring cell (called filopods)

21
Q

what happened with the 2008 outbreak of listeriosis?

A

-linked to cold cuts from the maple leaf food plant in toronto
-had a long progression
-february - july there were sporadic positive tests for listeria at the plant (had reduced sodium in the recipe which prevents growth and increased packaging size which meant longer defrosting times)
-early june was the earliest known human illness
-was not confirmed until mid august

22
Q

why was the listeriosis outbreak so drawn out?

A

-listeria monocytogenes has a long incubation period (up to 70 days) meaning symptoms dont appear for over 2 months after exposure making it hard to track back to the source
-similar symptoms to the flu (only known with a lab test)

23
Q

what are different foods fermented by microbes?

A

-tempeh (mold fermented)
-chocolate (cocoa bean fermentation)
-kombucha (fermented drink with a mix of bacteria, mix changes the flavour)
-bread (baker’s yeast fermentation)
-swiss cheese (holes = fermentation)
-wine and beer (alcoholic fermentation of fruit and grain)
-yeast and bacteria are major contributors, but mold as well

24
Q

how can we eat certain microbes by themselves?

A

-single-cell protein
-certain strains of yeast, fungi, algae, and bacteria
-derived from microbes with high protein and low fat content

25
what is an example of a single-cell protein?
-nutritional yeast -often a strain of inactive saccharomyces cerevisiae
26
why is nucleic acid also low in single-cell protein?
-do not want too many purines -purines get converted to uric acid which can cause gout and kidney stones
27
what is the polymerase chain reaction?
-enables the in vitro production of DNA -first step to editing DNA -assemble all the necessities of DNA replication in a test tube
28
what are the necessities for DNA replication for the polymerase chain reaction?
-DNA polymerase (Taq) -dNTPS (nucleobases) (A, T, C, G) -starting DNA template (short sequence)
29
what is the cycle of polymerase chain reaction?
-denaturation (heating that splits the DNA duplex, highest heat) -primer annealing (attachment of primers, lower heat) -extension (by DNA polymerase, higher heat)
30
how many cycles occurs in a polymerase chain reaction?
-20 - 30 (exponential fashion)
31
what are oligo nucleotide primers?
-custom synthetic sequences of DNA -very short -the starting template for PCR
32
can PCR be done randomly?
-yes -but typically is meant to be customized to amplify a specific sequence of DNA
33
how can primers be designed that allow for genetic engineering later?
-designed with overhangs (sticky ends) -easy to make recombinant DNA (joining of 2 or more molecules to create a hybrid)
34
what is genetic engineering?
-design of custom DNA to satisfy specific goals -delete genes of an organism to figure out their function -add a gene from one organism to another
35
what is the general workflow of genetic engineering?
-design primers to amplify a desired piece of DNA -use PCR to generate the product -purify and open a plasmid vector (creates selective pressure, typically antibiotic reistance) -paste the new DNA into the vector -introduce the vector into the target (transformation = introduction of foreign DNA into a cell)
36
why would the vector be for antibiotic reistance?
-allows for a antibiotic concentration to be added -kills the cells that did not take in the vector so you only have the desired population
37
how are vectors transformed into a cell?
-either with chemicals or electricity -goal is to weaken the cell so it will accept it
38
why is it important to figure out the function of genes?
-show the redundancy of genes -if it is taken away and has no effect on the overall function = redundant -if it is taken away and a function is lost, then you must add it back and see if it regains the function to prove that the gene truly relates to that function
39
what are specific applications of genetic engineering?
-make lots of a protein (ex: insulin) -monitor gene expression (turn genes on or off OR upregulate them using promotor sequences) -monitor protein localization -design a new synthetic gene regulation circuit (biosensors)
40
how is biotechnology used in cows to increase milk yields?
-bacterial expression of proteins is of interest -the genetic code is universal -bovine somatotropin is used to increase milk yields
41
what is the process of using biotechnology to induce bacterial expression of proteins?
-reverse transcriptase is used to convert mRNA to cDNA -the cDNA is added onto an expression vector with a bacterial promoter -it is then transformed into bacterial cells (specific) -it then goes through commercial production before it can be injected into an organism -done with human insulin and growth hormone commonly
42
how is biotechnology used in plants?
-essentially all plants we eat look nothing like their ancestors (genetically modified organisms) -ex: intentional radioactive mutagenesis is used to create ruby red grapefruit
43
what is Bt corn and how does it reduce the use of pesticides?
-a toxin gene that comes from bacillus thuringiensis is moved into a corn plant -this toxin gene allows for the corn to kill most insect pests (corn borer worms) -pesticides no longer need to be used
44
what is 'SunUp' papaya and how does it reduce the use of pesticides?
-papaya that is genetically modified to include the ringspot virus coat protein -there is now no need to kill the virus spreading aphids as the papaya does it on its own -a gene gun is used to introduce the DNA into the papaya germ plasm(carries hereditary information that gets passed down)
45
what is golden rice?
-rice that has phytoene synthase and desaturase genes engineered to express in endosperm -helps with vitamin A deficiency to prevent child blindness and death
46
what are biosensors?
-detect environmental contamination -genetically engineered bacteria detect environmental contaminants and produce a signal that is detected by the hardware -can be adapted to many pollutants (metals, PFAS) -rapid screening can be done
47
how is biotechnology used for medical diagonostics?
-used for PCR diagnostics -cancer gene screening -paternity testing -pathogen detection -antibiotic resistance testing
48
how does rapid antigen testing work?
-the test strip is loaded with antibodies that bind the nucleocapsid protein (SARS-CoV2) -the swab sample is loaded with buffer and when dropped onto the strip, it flows up through capillary action (chromatography) -if the nucleocapsid is present, then antibodies bind and the red line becomes visible

MBIO1010 (28 decks)

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