Bio 220: Lecture 07

Front 1

synchronous cultures

Back 1

technique that allows for studying cells that divide at the same moment. Goal is to get cells at the same age.
- Can be accomplished by using step-down and step-up experiments.
- Lowering temperatures will allow for all cells in division phase to complete division and then they will stop replication.
- Raising the temperature will not initiate division simultaneously
- Dilution of the media and then the reconcentration of the media will also achieve synchronous divisions.
- These methodologies allow researchers to assess and study replication

Front 2

What are the physical growth considerations?

Back 2

temperature, pH, and osmotic pressure

Front 3

What are the 3 major ranges associated with bacterial growth?

Back 3

psychrophiles, mesophiles, and thermophiles

Front 4

What are psychrophiles?

Back 4

cold loving optimum @ 15 degrees C

Front 5

What are mesophiles?

Back 5

moderate temperature loving optimum @ 37 degrees C

Front 6

What are thermophiles?

Back 6

heat loving optimum @ 50-60 degrees C

Front 7

What are the psychrotrophs?

Back 7

can grow at refrigerator temperatures and at temperatures beyond (above) the psychrophiles. The psychrotrophs are the most likely to be encountered in low-temperature food spoilage as they grow fairly well at refrigerator temperatures

Front 8

What are the hypertermophiles?

Back 8

(extreme thermophiles) have an optimum temperature of 80 degrees or higher. Members of the Archaea can be extreme thermophiles

Front 9

What is the danger zone temperatures?

Back 9

danger zone temperatures associated with possible food contamination from bacterial growth are 15 degrees C to 53 degrees C (60 degrees F to 130 degrees F). This is range where bacteria grow rapidly and some may produce toxins.

Front 10

pH

Back 10

most bacteria grow best in narrow range around neutrality.
- Some food products are preserved from spoilage due to acids produced from bacterial fermentation (such as sauerkraut, pickles and some cheese)

Front 11

A few bacteria are classified as _____.

Back 11

acidophiles

Front 12

organism: Thiobacillus thiooxidans

Back 12

• forms sulfuric acid as it metabolizes
• type of bacteria found in acidic mine water and can survive in a pH of 1

Front 13

Since bacteria typically produce acids as waste, what are often put into growth media?

Back 13

buffers

Front 14

Molds and yeasts grow over a _____ pH range

Back 14

greater
• Optimum pH (5 to 6) is on the acid side of neutrality

Front 15

How does osmotic pressure affect physical growth considerations?

Back 15

most bacterial organisms survive in a low osmotic environment (0.9% saline). This concentration is generally conductive to cellular life in general. Since 0.9% saline creates an osmotically balanced (isotonic) environment, we can refer to is as physiologic saline. Higher saline concentrations in the surrounding environment create a hyperosmotic (hypertonic) condition. This can cause cell shrinkage and plasmolysis. Lower saline concentrations in the surrounding environment can cause a hypo osmotic (hypotonic) condition. This can cause cell lysis from taking in too much water.

Front 16

High salt concentrations will ____ most microbial growth.

Back 16

inhibit (used as a method for food preservation ex: salt encrusted meats)

Front 17

define: halophilic

Back 17

salt lovers
-bacterial organisms survive the ocean (3.5% salt)
- bacteria survive in the Dead Sea (30% salt)
- members of the genus Halobacterium are halophilic

Front 18

define: saccharophilic

Back 18

sugar lovers (organisms that can survive in high sugar concentrations. Molds can survive in higher sugar environments than bacteria) ex. mold growing on the lid of a bottle of jam or jelly

Front 19

What is the structural backbone of living matter?

Back 19

Carbon

Approx. one half of the dry weight of a typical bacterial cell is carbon

Front 20

What are the major chemicals of life?

Back 20

CHOPKINS CaFe is MgNaCl

Front 21

What is an element in amino acids and proteins can also be found in nucleic acids?

Back 21

nitrogens

Front 22

define: aerobic

Back 22

require oxygen

Front 23

define: microaerophilic

Back 23

need oxygen, but less required (limited tolerance to toxic products associated with oxygen)

Front 24

What are the three types of anaerobes?

Back 24

obligate anaerobes, aerotolerant anaerobes and facultative anaerobes

Front 25

define: obligate anaerobes

Back 25

unable to use molecular oxygen for energy-yielding reactions. Most are harmed by the mere presence of oxygen
-Clostridium are obligate anaerobes.
- Toxic molecules associated with oxygen are oxygen metabolism cannot be broken down as the obligate anaerobes lack the enzymes capable of rendering these by products non-toxic. The enzymes referred to that are lacking are superoxide dismutase, catalase and peroxidase

Front 26

What are the three enzymes that obligate anaerobes will lack when toxic molecules associated with oxygen and oxygen metabolism cannot be broken down?

Back 26

superoxide dismutase, catalase, and peroxidase

Front 27

define: aerotolerant anaerobes

Back 27

cannot use oxygen for growth, but they can tolerate it. These organisms possess the enzyme superoxide dismutase

Front 28

define: faculative anaerobes

Back 28

will use oxygen when it is present. They can posses the enzyme superoxide dismutase and catalase. Can also grown when oxygen is not available. Their ability to produce energy decreases without oxygen. They have dual systems.
E. coli is an example of a facultative anaerobe.

Front 29

define: organic growth factors

Back 29

essential organic compounds that some organisms cannot synthesize and must be obtained from the environment. These include vitamins, coenzymes, nitrogen - containing bases such as the purines (adenine, guanine) and the pyrimidines (thymine, cytosine and uracil)

Front 30

define: trace elements

Back 30

additional elements that organisms might require in very minute amounts. Ex: selenium, cadmium, copper and zinc.
• Often found in water as impurities