BIOL-3303, EXAM 2

What is Microbial Growth:

The increase in CELL NUMBERS and NOT the increase in size

How does the microbial growth works:

First: cells grow to a critical mass

Second: cells divide

Third: they repeat the process

Finally: growth in exponential

What factors regulate microbial growth:

Nutrient availability

Environmental conditions such as temperature, pH, osmotic pressure

Generation time

What is generation time:

The time required by the bacteria to grow

Ex: Speed demon Vibrio natriegans doubles in less than 10 minutes

Without which two factors would bacterium multiply to a volume greater than earth in a day:

Extrinsic and intrinsic checks

What chemicals are required for the growth of microbes:

Water

Elements

Organics

What is the number one chemical requirement for the microbial growth:

Water

What are the seven elements required for the growth of microbes:

Carbon (50% of cell's dry weight)

Hydrogen

Oxygen

Nitrogen

Phosphorous

Sulfur

Trace elements

What organics are required by the microbes for its growth:

Glucose as a source of energy

Vitamins as coenzymes

Amino acids, purines, and pyrimidines

If an organism uses carbon dioxide as a source of carbon, they are considered as a:

Autotroph

If an organism uses Organic carbon as a source of carbon, they are considered as a:

Heterotroph

If an organism uses sunlight as a source of energy, they are considered as a:

Phototroph

If an organism uses Organic materials as a source of energy, they are considered as a:

Chemotrophs

Chemoheterotroph derive both carbon and energy from what

Organic Compounds

Photoheterotrophs derive carbon from ............ and energy from ............

Organic compounds; Sunlight

Photoautotrophs derive carbon from ............ and energy from ............

CO2; sunlight

Chemoautotrophs derive carbon from ............. and energy from .............

CO2; Organic Compunds

Psychrophiles are:

Cold-loving microbes

Mesophiles are:

Moderate temperature-loving microbes

Thermophiles are:

Heat-loving microbes

All psychrophiles, mesophiles, and thermophiles have a:

Minimum, Optimum, and Maximum growth temperature

On a graph, the optimum growth temperature is usually near:

The top of the growth range

What causes the death of microbes above the maximum temperature

Enzyme Inactivation

What macromolecules are unstable at high temperature

Proteins

Psychrophiles, Mesophiles, and Thermophiles are

Extremophiles

What is the most common Extremophile

Mesophiles

At what temperature does most microbes slow or stop its growth

40F (5C)

True or False: Extremophiles are ancient

True

Microbes are divided into three categories based on their oxygen requirements. What are they:

Obligated Aerobes

Facultative Anaerobes

Obligated Anaerobes

Obligated Aerobes:

Require Oxygen

Facultative Anaerobes:

Use Oxygen but can also grow with it

Obligated Anaerobes:

Die in the presence of Oxygen

Mycobacterium tuberculosis is:

An obligated aerobic that colonize the lung and cause Tuberculosis

Lactobacillus crispatus is:

A facultative anaerobe that colonize the vagina and urinary tract

Clostridium difficile is:

An obligated anaerobe that colonize the gut (potentially fatal gastrointestinal pathogen)

Most bacteria grow at what pH range:

pH 6.5 and 7.5

Acid (pH below 4) is good for :

Preservation (pickles, sauerkraut, cheeses)

Acidophiles can live at:

Low pH

Helicobacter pylori can live in your stomach at approximately what pH? what does H. pylori cause:

pH 2, Cause stomach ulcers

Lactobacilli helps maintain a low pH level (

Vagina; To prevent infection

What are the Four phases of microbial growth:

Lag Phase

Log Phase

Stationary Phase

Death Phase

What happens during the LAG phase:

Make new enzymes in response to new medium

What happens during LOG phase:

Exponential Growth

What happens during STATIONARY phase:

Plateaued Growth

What happens during DEATH phase:

Death exceeds division (die)

In Log phase, microbes are desired for:

Production of Products

During Log phase, microbes are sensitive to:

Drugs and Radiation

During stationary phase, nutrients become ............. and waste products become .............

Limited; toxic

During stationary phase, death rate is also know as:

Division Rate

What are the five steps of growing microbes in a lab:

1) Fill flask with growth media

2) Sterilize to kill any contaminating microbes

3) Aseptically add a very small amount of bacteria

4) Place the flask in a shaking incubator at 37C (if aerobic)

5) Return the next day and the culture is cloudy

Turbidity is used as:

A common way to measure bacterial growth

How is optical Density (OD) is measured:

Using a Spectrophotometer

How is Optical Density is measured using a spectrophotometer:

Light (600nm) passes through the sample, and a detector measures how much light passes through

A higher optical density means:

Less light passed through and more bacteria are present

True or False: Optical Density measures both viability and growth rate:

False

Optical density only measure ............, not the ..............:

Growth Rate; Number of Viable Cells

True or False: In stationary phase cells begin to die, but we cannot detect by simple optical density:

True

Colony Forming Unit (CFU) only measures:

Live Bacteria

What are the three steps of Colony Forming Unit:

1) Take samples at each time point and plate on an agar plate

2) Incubate the plates until visible colonies form

3) Count the colonies

Each colony on an agar plate was originally formed by a single bacterium unit or a:

Colony Forming Unit (CFU)

Do live or dead bacteria in a culture form colonies:

Only live bacteria

Counting viable cells can also be done by:

Flow Cytometry

What are the five steps of using a flow cytometry to find viable cells:

1) Treat cells with a live/dead stain

2) Propidium iodide (red) is taken up by dead cells

3) SYTO 9 (green) binds to live cells

4) Samples pass one at a time through a laser beam in the cytometer

5) Wavelength of light emitted reveals in stained green (live) and red (dead)

Is cell growth by Binary Fission is an exponential sequence or logarithmic sequence:

Exponential Sequence

Cell growth by binary fission is an exponential sequence, 2n, where n is:

The number of generations

The number of cells (N) after n generations beginning with N0 cells is calculated by:

N = 2^n(N0)

or

logN = n(log2) + logN0

If you know how many bacteria you started with, the number of generations can be calculated as:

n = (logN - logN0) / 0.301

For example, if you start with 10^3 bacteria (N0) and end with 10^9 (N) bacteria would be:

(9-3) / 0.301, or Approx. 20 generations

How do you calculate generation time:

Doubling time / Growth rate

AKA; g = t/n

(Check the slide #31)

Cells growing quickly increase in size and mass to accommodate what:

All the extra molecules needed to support growth

True or False: Quickly dividing cells are visibly distinguishable from slowly dividing ones:

True

Fast growth requires more protein synthesis, so ............. and .............. increase drastically:

Ribosomes; RNA

What are the four chemical processes distinguish life from non life?

1. Enzyme Catalysis

2. Energy Harvesting from Redox reaction

3. Energetically coupled reactions

4. Transduction of energy from transmembrane ion gradients

Enzyme Catalysis?

Accelerates slow reactions

Energy harvesting from redox reaction?

Oxidation/reduction to generate ATP and NADH

Energetically coupled reactions?

Link favorable and unfavorable reactions

Transduction of energy from transmembrane ion gradients?

Generate ion gradients to perform work or generate ATP

Reproduction of bacteria (Bacterial growth) results in a huge number of?

Chemical reactions

The metabolic framework of bacterial growth occurs through what four sequential processes?

1. Fueling

2. Biosynthesis

3. Polymerization

4. Assembly

All cellular structures are made up of versions (or combinations) of what 4 major building blocks?

1. Nucleic Acids

2. Proteins

3. Carbohydrates

4. Lipids

To understand microbial metabolism, we must first know?

What molecules need to be made

In what order do prokaryotes consume macromolecules for their biosynthesis, from highest to lowest?

1. Protein

2. RNA

3. Phospholipids

4. DNA

5. Glycogen

In prokaryotes, proteins make up ........ of the dry weight of the cell

55%

RNA is the second most abundant macromolecule with a dry weight of?

~20%

Phospholipids comprise ........ of the cell's dry weight, LPS ........., DNA .........

~9%; 3.4%; 3%

In order to divide, microbial metabolism needs to be focused on

Synthesizing macromolecules

Getting precursor metabolites, energy, and reducing power the cell needs for biosynthesis is known as?

Fueling Reaction

Cells need energy for many other processes besides the manufacture of building blocks. What are some examples?

1. Motility

2. Protein secretion

3. Repair

4. Sensing and communication

True/False: Both growing and non growing cells require energy?

True

Strategies to harness energy are diverse but they all converge into?

One Universal mechanism

Energy is conserved intracellularly in the energy-rich phosphate bonds of molecules like?

Adenosine Triphosphate (ATP)

ATP is the primary molecule for energy transfer because?

ATP is a small molecule that can store a lot of energy

Phosphate groups of ATP are highly negative or positive?

Negative

True/False: It takes a lot of energy to hold phosphate groups together?

True

When is energy from phosphate groups released?

When the phosphodiester bond is broken

What cellular activity demands the highest energy investment?

Growth

The process of growth initiates with?

Fueling reactions

What makes precursor metabolites from substrates taken up from the environment?

Fueling reactions

In Fueling reactions, microbes assimilate chemicals containing elements to make

Cell's 13 precursor metabolites

Precursor metabolites form?

The building blocks