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Clinical Bacteriology (Laboratory) > Prevent the rise of superbugs! (Labster Lab Manual | M) > Flashcards

Prevent the rise of superbugs! (Labster Lab Manual | M) Flashcards

1
Q

What is vertical gene transfer (bacterial vertical gene transfer)?

A

It refers to the inheritance of the parental gene to the progeny

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2
Q

Provide exs of prokaryotes

A

1) Bacteria

2) Archaea

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3
Q

How do prokaryotes reproduce?

A

Asexually by budding or cell division

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4
Q

What is the product of asexual reproduction of prokaryotes?

A

To generate identical progeny / daughter cells

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5
Q

Is the chromosome of the daughter cells identical to the parent cells?

A

Yes

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6
Q

Is genetic variation possible in vertical gene transfer? How?

A

Yes, through mutation

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7
Q

When is variation vital to a population of bacteria?

A

It becomes vital to a population of bacteria when it was exposed to change, such as new environment or competing microbes

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8
Q

The variation in bacteria genome may lead to what?

A

It may lead to progeny that are more adaptable towards the changes, hence ensuring the survivability of the bacteria spp

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9
Q

True or False

The genetic variation via mutation generally happens faster compared to horizontal gene transfer

A

False, because the genetic variation via mutation happens slowly compared to horizontal gene transfer

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10
Q

What is the process (or steps) of mutation in a population of non-resistant bacteria?

A

1) Non-resistant bacteria
2) Bacteria multiply
- > few bacteria will mutate as they multiply
3) Mutant survive
- > in the presence of antibiotics, only resistant bacteria survives
4) Antibiotic resistant
- > the cycle will repeat upon the exposure of more / new antibiotics

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11
Q

What is a genome?

A

It is the body of genetic information in a cell

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12
Q

What are the components of bacterial genome?

A

It mainly consists of:

1) Chromosome
2) Plasmid

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13
Q

The structure of both chromosome and plasmid are comprised of what?

A

DNA

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14
Q

What is a chromosome?

A

It is the main genetic element of bacteria

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15
Q

What is the characteristic of the chromosome of bacteria?

A

It usually has a circular shape unlike eukaryotic that has a linear shape

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16
Q

What is the component of the bacterial chromosome?

A

It is composed of DNA double helix

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17
Q

True or False

The chromosome is several hundred times longer than the bacterial cell itself

A

True

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18
Q

To fit the chromosomes in the cells, it is being what?

A

Supercoiled

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19
Q

What are mutations?

A

These are variations in the nucleotide sequence of a genome

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20
Q

When can mutations occur?

A

They can occur because of errors during DNA replication or damage to DNA

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21
Q

What are the 2 types of mutations caused by DNA damage?

A

1) Induced

2) Spontaneous

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22
Q

Induced mutations result from what?

A

These mutations result from exposure to mutagenic chemicals, UV rays, x-rays, or some other environmental agent

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23
Q

When do spontaneous mutations occur?

A

These mutations occur w/out any exposure to environmental agents

24
Q

What are spontaneous mutations?

A

They are a result of natural rxns taking place within the body

25
Q

What is the ultimate source of new alleles, or new genetic variation in any population?

A

Mutation

26
Q

What are the only mutations that can be passed onto offspring?

A

Mutations in gametes or gamete-producing cells (germ cells)

27
Q

True or False

There is also emerging evidence that some elements of the lifestyle of an organism can be passed on through epigenetics

A

True

28
Q

What are the outcomes on the phenotype of genetic changes caused by mutation?

A

1) The mutation reduces fitness -> i.e. causes lower likelihood of survival or fewer offspring
2) The mutation increases fitness
3) The mutation has no effect on fitness

29
Q

What are neutral mutations?

A

These are the mutation which has no effect on fitness

30
Q

True or False

Impact on fitness does not depend on the environment the organisms lives in

A

False, because impact on fitness also depends on the environment the organisms lives in

31
Q

Can mutations can also cause diseases in an organism? If yes, give an ex.

A

Yes, such as cancer

32
Q

What is the meaning of HGT?

A

Horizontal gene transfer

33
Q

What is HGT?

A

It is the movement of genetic elements bet cells that are not direct progeny

34
Q

What is the diff of HGT to vertical gene transfer?

A

HGT allows gene transfer bet diff bacteria spp while vertical gene transfer does not

35
Q

What are the ways where HGT may happen?

A

1) Conjugation
2) Transformation
3) Transduction

36
Q

Of the 3 mechanisms of HGT, what is considered to have the most significant influence is the spread of antibiotic resistance genes?

A

Conjugation

37
Q

Do all HGTs produce a cell w/ a new combination of genes (recombinant)?

A

Yes

38
Q

What are the fates of the DNA transferred to a new cell?

A

1) The DNA may be destroyed by DNA restriction enzymes
2) The DNA may replicate by itself; independent of chromosomes’ machinery (e.g. plasmid)
3) The DNA may be incorporated into the chromosome, creating a recombinant

39
Q

What is the product of asexual reproduction of bacteria?

A

Genetically identical progeny

40
Q

In order to survive the harsh environment, what does the bacteria require?

A

The bacteria require a genetic change that leads to a more adapted phenotype. Those genetics are made possible by mutation

41
Q

Who developed the experiment that models the evolution of bacteria toward antibiotic resistance?

A

The scientists from Harvard Medical School and at Technion-Israel Institute of Technology

42
Q

What is the experiment called that models the evolution of bacteria toward antibiotic resistance?

A

Microbial evolution and growth arena (MEGA)-plate

43
Q

The MEGA-plate experiment involves what?

A

1) A culture of non-resistant bacteria
2) A giant dish (120 X 60 cm) that contains a section of growth medium w/ a gradual increase of antibiotic
3) Lab environment that is suitable for 2 wks incubation

44
Q

What is the procedure (or steps) of MEGA-plate experiment?

A

1) The bacteria is grown on the plate section w/ no antibiotic
2) After several hrs, the bacteria colony fills all the sections w/out antibiotics
3) Then the growth becomes slower before the bacteria colony is able to move to the next plate section w/ 10x antibiotic concentration
4) The process repeats until the bacteria colony is able to reach the plate section 1000x antibiotic concentration
* The whole experiment took approx 2 wks

45
Q

What does the MEGA-plate experiment show?

A

It shows us that bacteria are able to mutate and achieve resistance towards high-concentration-antibiotic in a relatively short time

46
Q

What is antibiotic resistance?

A

It is the general process in w/c bacteria (usually infectious) becomes insensitive to a sp drug or a sp class of drugs

47
Q

When does antibiotic resistance usually appear?

A

It usually appears when a microbe is exposed to sub-lethal concentrations of a sp antibiotic: due to the selective pressure, the surviving microbes might develop resistance mechanisms across several generations through mutations in their DNA

48
Q

What are the categories of the resistance mechanisms?

A

1) The modification of the primary target of the antibiotic, such as transpeptidase for ampicillin resistance
2) The inactivation of the antibiotic compound itself, such as the production of B-lactamase enzymes to degrade penicillin G inside the cell
3) Preventing the antibiotic from reaching the target, by reducing the permeability of the membrane or using efflux pumps to keep the drug outside the cell as observed against ciprofloxacin for ex
4) Using alternative metabolic pathways to compensate for the action of the antibiotic and ensure the survival of the organism

49
Q

Provide an ex of the modification of the primary target of the antibiotic

A

Transpeptidase for ampicillin resistance

50
Q

Provide an ex of action of the inactivation of the antibiotic compound itself

A

Production of B-lactamase enzymes to degrade penicillin G inside the cell

51
Q

What is the action in terms of preventing the antibiotic from reaching the target?

A

By reducing the permeability of the membrane or using efflux pumps to keep the drug outside the cell, as observed against ciprofloxacin as ex

52
Q

What are the ways of transfer of the resistance gene by drug-resistant bacterial strain?

A

Can transfer the resistance gene:

1) To other strains of the same spp
2) To individuals of a diff spp altogether
* Both have never been exposed to the drug in the first place
* This way, antibiotic resistance can spread widely and compromise whole antibiotic therapies

53
Q

The accumulation of antibiotic resistance genes leads to what?

A

It leads to the creation of “superbugs”

54
Q

What are superbugs?

A

These are bacterial strains that are immune to all but the most drastic treatments

55
Q

What are the ways of how to overcome antibiotic resistance?

A

The current strategies are:

1) To discover new antibiotics w/ novel modes of actions
2) To use diff antibiotics in “cocktails” - presuming that the bacteria might survive facing 1, but not 2 or 3 antibiotics simultaneously

56
Q

What is the importance of antibiotic resistance genes in the lab?

A

In the lab, these are an important tool for genetic engineering to select for transformed cells

Clinical Bacteriology (Laboratory) (24 decks)

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