Ch 7

Question 1

What is most of the dry weight of a microbial cell?

Answer 1

• –organic compounds
• proteins
• nucleic acids
• RNA
• DNA
• carbohydrates
• Lipids

Question 2

What is the most prevalent compound in a cell?

Answer 2

• H20

- Water

Question 3

What elements are most common in a cell?

Answer 3

• Carbon
• Oxygen
• Nitrogen
• Hydrogen
• Phosphorus
• Sulfur

Question 4

Define macronutrient

Answer 4

• required in large quantities

- play principle roles in cell structure and metabolism

Question 5

Define trace elements

Answer 5

• micronutrients
• present in smaller amounts
• involved in enzyme function and maintenance of protein structure

Question 6

Define growth factors

Answer 6

• organic compound like an amino acid, nitrogenous base, or vitamin that cannot be synthesized by an organism
• must be provided by the environment

Question 7

Define phototroph

Answer 7

-microbes that photosynthesize

Question 8

Define autotroph

Answer 8

• self-feeder
• organism that uses inorganic CO2 as its carbon source
• have the capacity to convert CO2 into carbon compounds
• not dependent on other living things

Question 9

Define chemotroph

Answer 9

Microbes that gain energy from chemical compounds

Question 10

Define heterotroph

Answer 10

• organism that must obtain carbon in organic form
• dependent on other life forms
• most carbon sources exist in a form that is simple enough for absorption
• many carbon sources must be digested by the cell to be absorbed

Question 11

Define photoautotroph

Answer 11

• captures energy from light rays and transforms it into chemical energy for cell metabolism
• produces organic molecules that can be used by themselves and heterotrophs
• forms the basis for most food webs

Question 12

Define chemoheterotroph

Answer 12

-use organic compounds for energy and inorganic compounds as a carbon source

Question 13

Define diffusion

Answer 13

• the movement of molecules in an area from high to low concentration or density.
• diffusion across a cell membrane is made by the concentration gradient and the permeability of the substance.

Question 14

Define facilitated diffusion

Answer 14

• The movement of substances from higher to lower concentration across a semipermeable membrane
• must have a specific protein carrier but no energy expenditure

Question 15

Define active transport

Answer 15

-transports nutrients against a concentration gradient or with a concentration gradient at a faster rate

Question 16

Define osmosis

Answer 16

-the movement of water across a selectively permeable membrane.

Question 17

Define endocytosis

Answer 17

-The process by which a cell uses ATP to enclose a substance in its membrane, by forming a vacuole and engulfing it

Question 18

Define phagocytosis

Answer 18

-endocytosis by amoebas and certain white blood cells that ingest whole cells or large solid matter

Question 19

Define pinocytosis

Answer 19

-entry of oil or molecules in solution into the cell

Question 20

Define exocytosis

Answer 20

-the transport of material out of a cell by means of a sac or vesicle that first engulfs the material and then is extruded through an opening in the cell membrane

Question 21

What part of the bacteria mediates nutrient absorption?

Answer 21

-cell membrane

Question 22

What is the effect of cells when placed in a hypotonic environments?

Answer 22

The cells will swell and burst.

Question 23

What is the effect of cells when placed in a hypertonic environments?

Answer 23

The cells will shrink and shrivel.

Question 24

Define obligate

Answer 24

Necessary; essential to a particular condition of life

Question 25

Define facultative.

Answer 25

Does not require oxygen for its metabolism; capable of growth in the absence of oxygen

Question 26

Define halophile

Answer 26

Require high concentrations of salt for growth

Question 27

Define mesophile

Answer 27

- majority of medically significant organisms - individual species grow at 10-50 degrees Celsius - optimum growth temp 30-40 degrees Celsius - most human pathogens: 30-40 degrees Celsius

Question 28

Define thermophile

Answer 28

- grows at temp above 45 degrees Celsius to 80 degrees Celsius - lives in soil and water associated with volcanic activity, compost piles, habitats directly exposed to the sun

Question 29

Define psychrophile

Answer 29

-organisms that have an optimum temp below 15 degrees Celsius -capable to grow at 0 degrees Celsius Cannot grow about 20 degrees Celsius

Question 30

Define facultative psychrophile (psychrotroph)

Answer 30

- grows slowly in the cold | - have optimum temp between 15-30 degrees Celsius

Question 31

Define extremophile

Answer 31

-An organism that has adapted to extreme environments

Question 32

Define capnophile

Answer 32

- grow best at a higher CO2 tension than is normally present in the atmosphere - important in the isolation of some pathogens - incubation is carried out in a CO2 incubator that provides 3-10% CO2

Question 33

Define aerobes

Answer 33

- can use gaseous oxygen in its metabolism - has the enzymes needs to process toxic oxygen products Obligate aerobe: an organism that cannot grow without oxygen

Question 34

Define anaerobes

Answer 34

- lack metabolic enzyme system for using oxygen in respiration

Question 35

Define facultative anaerobes

Answer 35

- An aerobe that does not require oxygen for metabolism - Capable of growth in the absence of oxygen - Metabolized by aerobic respiration when oxygen is present - Adopts anaerobic metabolism (fermentation)) when oxygen is absent.

Question 36

Define microaerophiles

Answer 36

- does not grow at normal atmospheric conditions of oxygen - requires a small amount of oxygen in its metabolism - usually live in a habitat that provides a small amount of oxygen but not directly exposed to the atmosphere

Question 37

What does it mean if an organism is considered thermoduric?

Answer 37

The organism can survive short exposure to high temperatures such as common contaminants of heated or pasteurized foods.

Question 38

To survive in an oxygen environment, what enzymes would be key to a bacterium? How do they work?

Answer 38

Catalase and superoxide dismutase

Question 39

Define parasitic

Answer 39

Derive nutrients from the cells or living tissues of a host

Question 40

Define saprobic

Answer 40

Free-living microorganisms that feed primarily on organic detritus from dead organisms

Question 41

Define commensal

Answer 41

Receives benefits

Question 42

Define mutualistic relationships

Answer 42

- Obligatory, dependent | - both members benefit

Question 43

Define pathogen

Answer 43

Can damage tissues and cause death

Question 44

What is generation time?

Answer 44

- the time required for complete cycle - each new fission cycle doubles population - environment stays favorable, the doubling effect will stay a constant rate - It's the length of time measured of growth rate of an organism

Question 45

What is the phases of the bacterial growth curve?

Answer 45

- Lag Phase - Exponential growth or log phase - Stationary growth phase - Death phase

Question 46

What is the process for the viable plate count method? What do the results indicate?

Answer 46

- the total number of cells is counted over a given time period - the results indicate growth

Question 47

Know about the environment in which methanogen bacteria are found.

Answer 47

anaerobic, hydrogen-containing microenvironments such as ocean vents and hot springs

Question 48

what occurs in each phase? | Lag phase

Answer 48

- flat period on the graph - population appears not to be growing - newly inoculated cells require a period of adjustment, enlargement, and synthesis

Question 48

what occurs in each phase? | Log Phase

Answer 48

- Growth curve increases dramatically | - phase will continue as long as cells have adequate nutrient and the environment is favorable

Question 49

what occurs in each phase? | Stationary growth phase

Answer 49

- population enters survival mode | - cells stop growing or grow slowly

Question 50

what occurs in each phase? | Death phase

Answer 50

- Limiting factors intensify - cells begin to die at an exponential rate - curve dips downwards