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Introduction to Microbiology - Sem2 > Introduction to microbiology - SEM2 > Flashcards

Introduction to microbiology - SEM2 Flashcards

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1
Q

What is microbiology?

A

the study of the biology of microscopic organisms - viruses, bacteria, algae, slime moulds and protozoa

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2
Q

what does micro stand for in microbiology?

A

it can’t be seen with the naked eye

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3
Q

what does ology mean in microbiology?

A

study of

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4
Q

what is acellular?

A

not consisting of or divided into or containing cells:
viruses - non-living cells, a lack of cellular structure

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5
Q

What are living cells - cellular?

A
  • maintain structure by taking up chemicals and energy from the environment
  • respond to stimuli in the external environment
  • reproduce and pass on their organisation to their offspring
  • evolve and adapt to the environment
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6
Q

What do prokaryotic cells not have?

A

a nucleus

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7
Q

What does a eukaryote cell have?

A

a nucleus

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8
Q

What are the 6 kingdoms?

A
  • eubacteria
  • archae
  • protist
  • plant
    *fungi
    *animal
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9
Q

What are the 3 domains?

A

*bacteria
*archae
*eukarya

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10
Q

What does a typical eukaryotic cell include?

A
  • cilia
    *mitochondrion
    *cytoplasm
    *nucleoulus
    *chromatin
    *ribosomes
    *rough endoplasmic reticulum
    *lysosome
    *centrioles
    *microtubules
    *golgi apparatus
    *smooth endoplasmic reticulum
    *nuclear membrane
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11
Q

What does a typical prokaryotic cell include?

A

*outer membrane
*cell wall
*plasma membrane
*cytoplasm
*nucleoid region
*flagella
*fimbriae

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12
Q

What are the differences between a prokaryotic cell and a eukaryotic cell?

A

Prokaryotic cells:
* small cells (<5um>
*always unicellular
*no nucleus or any membrane-bound organelles
*DNA is circular, without proteins
*ribosomes are small (70S)
*no cytoskeleton
*cell division is by binary fission
*reproduction is always asexual

Eukaryotic cells:
*larger cells (>10um)
*often multicellular
*always have a nucleus and other membrane-bound organelles
*DNA is linear and associated with proteins to form chromatin
*ribosomes are large (80S)
*always has a cytoskeleton
*cell division is by mitosis or meiosis
* reproduction is asexual or sexual

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13
Q

What does Gram-positive have and do?

A

*a thicker cell wall
*provides greater protection from environmental stresses
*they are composed of approximately 20 layers of peptidoglycan and teichoic acid

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14
Q

What does Gram negative have and do?

A

*cell wall is multi-layered and complex
*it contains only a thin single layer of peptidoglycan (10% cell wall)
* periplasm and outer membrane

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15
Q

What does the outer layer membrane in the gram negative bacteria do?

A
  • protects them from the environment
  • the bacteria can use this membrane to selectively keep antibiotic drugs from entering
  • germs are to get rid of antibiotics using pumps in their cell walls to remove antibiotic drugs that enter cell
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16
Q

What is the use of antibiotics?

A
  • cell wall synthesis - penicillin
  • protein synthesis - chloramphenicol
  • disrupt membranes; gram negative bacteria - polymyxins
  • DNA synthesis - fluoroquinolones
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17
Q

What does the typical virus Genome (nucleic acid core) contain?

A

the genetic information as ds/ss - RNA or DNA

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18
Q

What is the typical virus Capsid?

A

a protective protein coat during transmission and often target for host immune response

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19
Q

Is the Envelope present in all viruses?

A

no

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20
Q

What is the treatment for viruses?

A

Acyclovir (is an antiviral medication). It is primarily
used for the treatment of herpes simplex virus infections,
chickenpox, and shingles. Other uses include prevention of
cytomegalovirus infections following transplant and severe
complications of Epstein–Barr virus infection.
AZT (Zidovudine): is an antiretroviral medication used to
prevent and treat HIV/AIDS. It is generally recommended for
use in combination with other antiretrovirals.

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21
Q

What are infectious microbes that consist of a segment of nucleic acid (either DNA or RNA) surrounded by?

A

a protein coat
- not cellular
- very small nm
- visible using EM
- RNA or DNA

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22
Q

Can a virus replicate alone?

A

No, it must infect cells and use components of the host cell to make copies of itself

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23
Q

Are typical viruses affected by antibiotics?

A

no

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24
Q

What are examples of viruses?

A
  • bacteriophage (DNA)
  • tobacco mosaic virus (RNA)
  • adenovirus (DNA)
  • influenza virus (RNA)
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25
Q

What is the lag phase?

A

increased metabolic activity of cells due to the synthesis of enzymes proteins, DNA, and an increase in cell size

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26
Q

What is the log (exponential) phase?

A

doubling of the cell population at regular intervals

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27
Q

What is the stationary phase?

A

there is no net increase or decrease in cell number

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28
Q

What is the death phase?

A

cell viability decreases exponentially

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29
Q

What is the generation time?

A

the time interval required for bacterial cells or population to double

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30
Q

What do generation times vary between?

A

12 minutes to 24 hours for bacteria

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31
Q

What is bacterial division?

A

the genetic material of the prokaryotes (chromosomes) is found in a specific area of the cell inside the cytoplasm, known as the nucleoid

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32
Q

What is binary fission?

A

a type of asexual mode of reproduction

33
Q

When does binary fission begin?

A

when the DNA of the bacterium divides into two (replicates)

34
Q

What is the second step of binary fission?

A

the bacterial cell then elongates and splits into two daughter cells each with identical DNA to the parent cell

35
Q

What is the third step of binary fission?

A

each daughter cell is a clone of the parent cell

36
Q

What are the benefits of binary fission?

A
  • only one parent is needed to reproduce
  • rapid division (escherichia coli division every 20 minutes)
  • daughter cells are clones of their parent cells
37
Q

What is bidirectional replication?

A

replicating DNA in two directions at the same time; from the origin of replication in the circular DNA found in most bacteria

38
Q

What are the two strands?

A

a leading strand (were replication occurs more rapidly) and a lagging strand (with slower replication)

39
Q

What is the semi-conservative replication?

A
  • seperation of the two strands of nucleotides
  • formation of a template from both strands for free nucleotides to bind to and create the two identical daughter strands
  • each daughter strand strand has half of the DNA from the original strand and half newly formed DNA
40
Q

What is the horizontal gene transfer (HGT/ lateral gene transfer (LGT)?

A

the movement of genetic material between unicellular and/or multicellular organisms other than by the transmission of DNA from parent to offspring

41
Q

What is the HGT?

A

the direct transfer of genetic material (DNA) between different genomes

42
Q

What important role does HGT play?

A

in the adaptation and evolution of organisms and is the primary mechanism for the spread of antibiotic resistance in bacteria

43
Q

What is artificial horizontal gene transfer?

A

a form of genetic engineering (designing artificial constructs to cross species barriers and to invade genomes)

44
Q

What is transfection?

A
  • the process of process of introducing nucleic acids into cells by non-viral methods
  • a powerful analytical tool for the study of gene function and regulation and protein
45
Q

What is transduction?

A

the process whereby foreign DNA is introduced into another cell via a viral vector

46
Q

What is conjugation?

A

the process by one bacterium transfers genetic material to another through direct contact

47
Q

What is transformation?

A

the process of DNA uptake by the bacteria from the surrounding environment

48
Q

What is viral transfection?

A

uses genetically modified viruses which are no longer pathogenic and carry the gene to be introduced

49
Q

What is the first bacterial transduction step?

A

the bacteriophage first infects the donor cells and begins the lytic cycle

50
Q

What is the second step of bacterial transduction?

A

the virus then develops its components using the host cell machinery

51
Q

What is the third step of bacterial transduction?

A

the host cell DNA is hydrolysed into small fragments by the viral enzymes

52
Q

What is the fourth step of bacterial transduction?

A

small pieces of bacteria DNA is now integrated into viral genome

53
Q

What is the last step of bacterial transduction?

A

when the virus infects another bacteria the DNA is transferred into it

54
Q

What occurs during conjugation?

A

one bacterium serves as the donor of the genetic material and the other is to serve as the recipient

55
Q

What does the donor bacterium carry a DNA sequence called?

A

the fertility factor (f factor)

56
Q

What is the drawback for binary fission?

A

the lack of genetic recombination the species can’t survive the changes in their environment and the whole population is wiped out

57
Q

What does DNA replication have?

A

no nucleus - condensed DNA in nucleoid
single circular chromosome
replication - 40 mins at 37 degrees

58
Q

Is replication bidirectional and semi-conservative?

A

they are bidirectional and semi-conservative - so both

59
Q

How is replisome formed?

A

the proteins involved in DNA replication aggregate at the replication forks to form a replication complex - replisome

60
Q

What is the first step of the replication in E. coli initiate?

A

at the single genomic site called oriC (origin of replication), where two multi-protein complexes - replisomes are assembled

61
Q

What is the second step of the replication of E. coli?

A

after replisomes are assembled, they are to replicate the chromosomes bi-directionally away from oriC and then after the entire genome is duplicated they are to meet again and terminate at specific Tus sites 1 & 2 in the ter reigon

62
Q

How many mutations occur every hour?

A

mutation event is very rare but microbial populations are large - 30 mutations per hour
hence rapid adaption - antibiotic resistance

63
Q

In bacterial competence, what is all bacteria not capable of?

A

taking up DNA from the surrounding environment,
an examplle is bacteria are made artifically competent and this is acheived by using chemicals and electrical pulses

64
Q

What occurs in the chemicals in bacterial competence?

A

cell permability using calcium phosphate.
they are to then be incubated with the DNA and provided with a heat shock treatment that causes the DNA to enter the cells

65
Q

What happens in electroportation in bacterial competence?

A

the bacterial cells are subjected to electrical pulses to make them permeable and causes the DNA to enter into cells

66
Q

How to identify transformed cells?

A

the bacteria are grown on an agar medium with antibiotics to check for trasformed cells, the others are non-transformed

67
Q

Give an example of a transgenic microorganism?

A

the bacterial strain that produces human insulin; genetic engineering

68
Q

What is the % of bacteria in human pathogens?

A

1%

69
Q

What % of bacteria are in plant diseases?

A

4%

70
Q

What is the % of bacteria in non-pathogenic?

A

95%

71
Q

What is bacteria known as?

A

primary decomposers - recycle nutrients back into the environment (sweage treatment plants)

72
Q

What do microbes trigger?

A

the immune response that suppresses infections
helpful bacteria does not just aid digestion they also fend off the flu

73
Q

What does our normal microbial flora prevent?

A

potential infections

74
Q

What are probiotics a mixture of?

A

live bacteria and yeast that lives in the body
they are good bacteria that help keep you healthy pathogens from gaining access to the body

75
Q

What can probiotics help with during flu season?

A

can help by preventing the replication of viruses in the body, stimulating the secretion of antibodies that protet against respiratory infections and suppoting a healthy immune system by maintaining a healthy gut microbiome
Lactobacillus rhamnosus, LGG® and Bifidobacterium,
BB-12® probiotic strains (hereafter referred to by use of
the trademarks LGG® and BB-12®) on the incidence,
symptoms and duration of flu-like sickness

76
Q

What is antibiotic production?

A

a substance that is produced by a micro-organism (or a similar substance produced as whole or partly by chemical synthesis) which at low concertrations kill or inhibit the growth of other micro-organisms

77
Q

What does bioremediation do and what is it?

A

decontamination of hazardous waste
microbes used to clean up pollutants and toxic wastes

78
Q

What are microorganisms to include?

A

vast and diverse groups including prokarotes, eukaryotes and acellular viruses
they undertake a variety of functions that can both be beneficial and detrimental

Introduction to Microbiology - Sem2 (1 decks)

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