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Microbiology > Bacteriology > Flashcards

Bacteriology Flashcards

1
Q

What is bacterial physiology

A

This refers to the life processes of bacteria that are needed for its growth and replication

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2
Q

What type of bacteria are mostly found in humans

A

Mesophiles- these bacteria grow best at moderate temperature

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3
Q

Name four groups of bacteria based on their temperature requirements

A

Psychrophiles- cold loving bacteria. (50degrees C and 150degrees C)
Thermophiles-heat loving bacteria
Hyperthermophiles- require very high temperature
Mesophiles- grow best at moderate temperature (25degrees and 45degrees)

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4
Q

What are the types of aerobic bacteria

A

Obligate aerobes- grow only in the presence of oxygen example vibrio cholerae

Facultative anaerobics-aerobes that can grow in the absence of oxygen.

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5
Q

Most bacteria of medical importance belong to which group of bacteria according to oxygen requirements

A

Facultative anaerobics

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6
Q

Name three types of bacteria under anaerobic conditions

A

Obligate anaerobes- these are killed by oxygen and grow in the absence of it
Microaerophilic-grow best in the presence of low oxygen tension
Aerotolerant-can’t use oxygen but can grow in its presence

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7
Q

Majority of pathogenic bacteria grow best under what kind of pH

A

Neutral or slightly alkaline pH

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8
Q

What are acidophiles and give one example

A

Bacteria that do well under acidic pH. Example lactobacilli

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9
Q

Bacteria divides by?

A

Binary fission

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10
Q

What is generation time?

A

This is the time needed for bacteria to double its population

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11
Q

Is generation time practical?

A

No because as bacteria keep dividing they produce more waste and utilize lots of nutrients so they will not always use the stipulated amount of time to double their population.
They will not always have favorable conditions to grow .
Example- E. coli’s generation time is 20 minutes but in reality, if it is faced with unfavorable conditions, it will not double its population in those twenty minutes

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12
Q

Bacteria do not divide exponentially true or false

A

False

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13
Q

Name two ways of measuring bacterial growth

A

Total count- number of cells in the samples.( the living and dead cells together)
Viable count- measures the number of living cells in the sample

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14
Q

State the phases in the bacterial growth curve

A
  1. Lag phase
  2. Log phase
  3. stationary phase
  4. death or decline phase
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15
Q

State what occurs at lag stage of the bacteria growth curve

A

At the lag phase: the bacteria have just been added to the media and it has started taking up nutrients so there is no increase in the number of viable cells although the bacteria already in the cell increase with size. They also adapt to the new environment at this stage

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16
Q

What occurs at the log phase

A

As the name implies, the bacteria numbers increase exponentially as the bacteria are done adapting to the new environment so conditions are favorable for growth

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17
Q

What occurs at the stationary phase

A

The rate at which the bacteria cells divide is equal to the death rate because most of the nutrients have been used up and there is a lot of toxic waste produced.

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18
Q

At what stage do bacteria for spores in the growth curve

A

Stationary stage

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19
Q

What occurs at the death phase

A

The population of the bacteria decreases due to death. There is toxic waste accumulation. There is an exponential decrease in the number of living bacteria cells

20
Q

State five nutritional requirements of a bacteria cell along with their importance to the cell

A
  1. Water- serves as a medium for entry of nutrients into the cell
  2. Nitrogen source- are in the form of ammonium salts and are major components of proteins and nucleic acids. The flagella are formed by proteins
  3. carbon source
  4. Inorganic salts- required for osmoregulation. Phosphate ( forms ATP)
  5. Growth factors- some bacteria require extra materials to make it grow
21
Q

Which media supports the growth of many bacteria

A

Simple media example agar or nutrient broth

22
Q

Which media contains additional nutrient for growth of fastidious bacteria and is solid

A

Enriched media example- blood agar

23
Q

Which media is enriched but is liquid instead of solid

A

Enrichment media

24
Q

Which media allows only certain bacteria to grow and inhibits the growth of other organism

A

Selective media example mannitol salt agar- which has increased salt concentration which is suitable for only staphylococcus species

MacConkey agar- used to grow only enteric bacteria

25
Q

What media determines which colony of bacteria is growing and changes colors

A

Indicator media- example, mannitol salt agar and macConkey agar

26
Q

Is the genetic information of bacteria encoded in DNA or RNA

A

DNA

27
Q

What are the processes that lead to variation in bacteria

A

Mutation-inversion,duplication

Horizontal gene transfer- Conjugation, transformation, transduction

28
Q

What re the causes of mutation

A

Copying errors

Mutagens

29
Q

What are the effects of mutation

A

Virulence
Antibiotic resistance
Adaption to humans

30
Q

What are plasmids

A

Circular DNA molecules which have extra chromosomes and don’t affect the bacteria life processes but help the bacteria to acquire additional properties on the host bacteria
Examples- formation of pilus , resistance to antibiotics

31
Q

Function of pilus

A

For gene transfer from one bacteria cell to another bacteria cell of similar characteristics

32
Q

In which horizontal gene transfer process is the exchange of genetic information between the two parent bacteria unequal in that one parent gives the genetic information while the other simply receives it but doesn’t give any genetic info

A

Conjugation

33
Q

Which horizontal gene transfer process works by the bacteria taking naked DNA from a lysed bacteria cell?

A

Transformation

34
Q

What is competency

A

The ability of a bacteria cell to take up naked DNA

35
Q

F+ is a fertility gmfactor which shows the bacteria is not fertile true or false

A

False

36
Q

What is transduction

A

Transfer of genetic information from one bacteria cell to another via bacteriophage ( bacteria- viruses)

37
Q

State the two types of transduction

A

Generalized - involves the transfer of a random region of DNA of donor cell
specialized transduction - involves transfer of a specific region of DNA of donor cell

38
Q

What is the difference between pathogenicity and virulence

A

Pathogenicity is the ability of a microbe to cause disease in an infected host while virulence is how pathogenic a bacteria is

39
Q

State five virulence factors

A
  1. Adherence - Ability to stick to the surface of the host. ExMple- pili, flagellum
  2. Invasion- ability of the pathogen to spread to other locations in the host. Enzymes involved-?collagenases
  3. Bacterial toxins
  4. Siderophones- iron binding factors that low the bacteria to compete with the host for iron by being released to find iron and bring it back to the bacteria
  5. Immune invasions- ability to evade components of the host defenses
40
Q

How are bacteria able to evade the immune system

A
  1. Using bacteria capsules
  2. By destroying antibodies
  3. By surviving within the host cells
  4. Antigen variation( they keep changing the antigen so even if vaccines are being produced, the bacteria’s antigen will change so the vaccine will be ineffective)
41
Q

Differentiate between endotoxins and exotoxins

A

Exotoxins are produced in the bacteria cell as a result of metabolic activities and released outside while the bacteria is alive ( Gram negative bacteria Gram positive bacteria) while endotoxins Re part of the outer membrane (specifically the lipid A portion ) of the bacteria cell and are only produced when the bacteria cell dies. Example- Gram negative.
Endotoxins are heat stable and cause fever, shock, death
Exotoxins are hear sensitive and may be carried on plasmids

42
Q

What are normal flora

A

Population found regularly at anatomical sites of healthy individuals

43
Q

Which parts of the body is it abnormal to find microbes at?

A

Internal tissues
Blood
Brain
Musclesu

44
Q

Types of flora

A

Resident flora- always present
Transient flora-present only for a short period of time
Example- skin flora, GIt flora

45
Q

What shows the dynamic nature of normal

Flora

A
  • . Foetus are born sterile
  • microbes encountered at birth take up residence on the newborn
  • antibiotics can alter normal flora
46
Q

Importance of normal flora

A

Helps digest food
Stimulates the immune system
Lowers pH so other bacteria can’t grow
Produced vitamins we are unable to produce such as vitamin B12
Competing with harmful pathogens for space and nutrients

47
Q

Name three microbes found in the large bowel

A

E. coli,E. Faecium,enterobacter species

Microbiology (9 decks)

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