Bacteriology

Question 1

What is bacterial physiology

Answer 1

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

Question 2

What type of bacteria are mostly found in humans

Answer 2

Mesophiles- these bacteria grow best at moderate temperature

Question 3

Name four groups of bacteria based on their temperature requirements

Answer 3

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)

Question 4

What are the types of aerobic bacteria

Answer 4

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

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

Question 5

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

Answer 5

Facultative anaerobics

Question 6

Name three types of bacteria under anaerobic conditions

Answer 6

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

Question 7

Majority of pathogenic bacteria grow best under what kind of pH

Answer 7

Neutral or slightly alkaline pH

Question 8

What are acidophiles and give one example

Answer 8

Bacteria that do well under acidic pH. Example lactobacilli

Question 9

Bacteria divides by?

Answer 9

Binary fission

Question 10

What is generation time?

Answer 10

This is the time needed for bacteria to double its population

Question 11

Is generation time practical?

Answer 11

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

Question 12

Bacteria do not divide exponentially true or false

Answer 12

False

Question 13

Name two ways of measuring bacterial growth

Answer 13

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

Question 14

State the phases in the bacterial growth curve

Answer 14

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

Question 15

State what occurs at lag stage of the bacteria growth curve

Answer 15

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

Question 16

What occurs at the log phase

Answer 16

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

Question 17

What occurs at the stationary phase

Answer 17

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.

Question 18

At what stage do bacteria for spores in the growth curve

Answer 18

Stationary stage

Question 19

What occurs at the death phase

Answer 19

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

Question 20

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

Answer 20

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

Question 21

Which media supports the growth of many bacteria

Answer 21

Simple media example agar or nutrient broth

Question 22

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

Answer 22

Enriched media example- blood agar

Question 23

Which media is enriched but is liquid instead of solid

Answer 23

Enrichment media

Question 24

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

Answer 24

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

Question 25

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

Answer 25

Indicator media- example, mannitol salt agar and macConkey agar

Question 26

Is the genetic information of bacteria encoded in DNA or RNA

Answer 26

DNA

Question 27

What are the processes that lead to variation in bacteria

Answer 27

Mutation-inversion,duplication | Horizontal gene transfer- Conjugation, transformation, transduction

Question 28

What re the causes of mutation

Answer 28

Copying errors | Mutagens

Question 29

What are the effects of mutation

Answer 29

Virulence Antibiotic resistance Adaption to humans

Question 30

What are plasmids

Answer 30

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

Question 31

Function of pilus

Answer 31

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

Question 32

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

Answer 32

Conjugation

Question 33

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

Answer 33

Transformation

Question 34

What is competency

Answer 34

The ability of a bacteria cell to take up naked DNA

Question 35

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

Answer 35

False

Question 36

What is transduction

Answer 36

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

Question 37

State the two types of transduction

Answer 37

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

Question 38

What is the difference between pathogenicity and virulence

Answer 38

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

Question 39

State five virulence factors

Answer 39

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 4. Immune invasions- ability to evade components of the host defenses

Question 40

How are bacteria able to evade the immune system

Answer 40

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)

Question 41

Differentiate between endotoxins and exotoxins

Answer 41

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

Question 42

What are normal flora

Answer 42

Population found regularly at anatomical sites of healthy individuals

Question 43

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

Answer 43

Internal tissues Blood Brain Musclesu

Question 44

Types of flora

Answer 44

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

Question 45

What shows the dynamic nature of normal | Flora

Answer 45

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

Question 46

Importance of normal flora

Answer 46

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

Question 47

Name three microbes found in the large bowel

Answer 47

E. coli,E. Faecium,enterobacter species