Chapter 6

Question 1

– Thrive in moderate environments:
– Temperature: Around 37°C (human body temperature).
– pH: Neutral to slightly alkaline (around pH 7.4).
– Oxygen: Aerobic, anaerobic, or facultative anaerobic.

Answer 1

Normophiles (Mesophiles):

Question 2

o Escherichia coli (E. coli)
o Staphylococcus aureus
o Salmonella species
o Streptococcus species
are what type of pathogens

Answer 2

Normophiles (Mesophiles):

Question 3

pathogen that need oxygen

Answer 3

aerobic

Question 4

pathogen that lives in the presence of no oxygen

Answer 4

anaerobic

Question 5

pathogen that lives in the presence of both oxygen and no oxygen

Answer 5

facultative anaerobic

Question 6

These bacterias thrive in extreme environments:

Answer 6

▪ Extremophiles

Question 7

pathogen that thrives in high temperatures (e.g., hot springs).

Answer 7

Thermophiles

Question 8

Pathogen that thrives in high salt concentrations

Answer 8

Halophiles

Question 9

pathogen that thrives in very acidic conditions

Answer 9

Acidophiles

Question 10

This type of pathogen is rarely pathogenic!

Answer 10

Extremophiles, as the human body does not provide environment conditions needed for survival

Question 11

Psychrophile

Answer 11

Thrive in cold temperatures

Question 12

Growth in which populatiion size doubles at a fixed rate is called what?
For example: two cells divide to become four cells, then four
cells divide to become eight.

Answer 12

exponential growth.

Question 13

In an environment with few bacteria but plenty of resources, bacteria will divide at a constant interval called?

Answer 13

the generation time (also called doubling time).

Question 14

Bacteria are preparing their call machinery for growth

Answer 14

lag phase

Question 15

growth approximates an exponential curve

Answer 15

log phase

Question 16

cells stop growing and shut down their growth machinery while turning on stress responses to help retain viability

Answer 16

stationary phase

Question 17

cells begin to die at an exponential rate

Answer 17

death phase

Question 18

for detailed laboratory studies, microbes must be grown separately in?

Answer 18

Pure cultures (single species)

Question 19

bacterial culture media can be?

Answer 19

liquid or solid

Question 20

a) … media is useful to separate
mixtures of different organisms.

Answer 20

solid

Question 21

a)… media allows bacteria to move
freely.

Answer 21

liquid

Question 22

allows for separation
of colonies into pure
cultures.

Answer 22

isolation streaking

Question 23

Bacterial cells form a) …. on solid media with agar added to make a firm surface.

Answer 23

colonies

Question 24

Compounds in the media prevent some types of bacteria from growing, favoring the growth of one specific type.

Answer 24

selective media

Question 25

Species grow equally well but compounds in the media are metabolized differently, often distinguished by a color indicator.

Answer 25

Differential media

Question 26

A medium that does both selective and differential agents

Answer 26

MacConkey medium

Question 27

# **MacConkey medium** bile salts and crystal violet, which prevent the growth of bacteria other than Gram-negative enteric bacteria.

Answer 27

Selective agents

Question 28

# **MacConkey medium** is lactose, which some bacteria ferment (pink) and others do not.

Answer 28

differential agent

Question 29

compounds a microbe cannot make itself but must gather from its immediate environment if the cell is to grow and divide.

Answer 29

Essential nutrients

Question 30

In the gut, dietary proteins are broken down into a..., which are further deaminated to release b)...

Answer 30

a) amino acids b) ammonia.

Question 31

is needed by cells to make proteins and nucleic acids.

Answer 31

nitrogen

Question 32

converts nitrogen to various forms.

Answer 32

nitrogen cycle

Question 33

# **happening in bacteria outside of the body** Some bacteria perform a) ... to convert nitrogen gas (N2) to ammonium ions (NH4+), which is a form that can be used for biosynthesis.

Answer 33

a) nitrogen fixation

Question 34

bacteria transform ammonia to nitrate NO3

Answer 34

nitrification

Question 35

bacteria transform ammonia to nitrate NO3 and then convert nitrate to N2, which is called?

Answer 35

denitrification

Question 36

if nitrite is found in the urine we can say what?

Answer 36

That there is a presence of a bacteria because normal human body mechanisms will not reduce nitrate to nitrite

Question 37

look for the metabolites of nitrite reductase, an enzyme generated by a variety of microorganisms.

Answer 37

Nitrite tests

Question 38

nitrite tests have a * sensitivity of: * specificity of:

Answer 38

* sensitivity of: 25% and a * specificity of: 94-100%

Question 39

catch everything (find the disease or true positives).

Answer 39

sensitive test

Question 40

are exclusive (confirm only the healthy or true negatives)

Answer 40

Specific test

Question 41

* Require oxygen for energy metabolism * Successfully detoxify reactive oxygen species (ROS) * Survive only in environments with oxygen

Answer 41

strict aerobes

Question 42

* Do not require oxygen for energy metabolism * Generally unable to detoxify ROS, making oxygen toxic * Survive only in environments without oxygen

Answer 42

Strict anaerobes

Question 43

* Aerobic, but ROS can be toxic * Survive in environments with lower oxygen concentration

Answer 43

Microaerophiles

Question 44

* Anaerobic but less susceptible to ROS, and usually lack catalase * Prefer anaerobic conditions * Cannot use oxygen but tolerates it's presence

Answer 44

Aerotolerant anaerobes

Question 45

* Aerobic AND anaerobic * Can use oxygen if it is present but can grow without it

Answer 45

Facultative anaerobes

Question 46

an enzyme produced by bacteria that catalyzes the decomposition of hydrogen peroxide into oxygen and water.

Answer 46

Catalase

Question 47

▪ In the catalase test, bacteria are exposed to?

Answer 47

hydrogen peroxide

Question 48

Bacteria capable of synthesizing catalase will contain a)... as a result of the reaction

Answer 48

bubbles

Question 49

If **no** bubbles are present in a catalase test =

Answer 49

bacteria is anaerobic

Question 50

if bubbles **are** present in a catalase test =

Answer 50

bacteria is aerobic