Microbiology Chapter 6: Microbial Nutrition and Growth

About 96% of the cell is composed of which elements?

(CHONPS) carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur

Which of the following conditions would cause a bacterial culture in exponential phase to shift to stationary phase?

- Drop in temperature - Loss of a nitrogen source

Which of the following molecules require nitrogen for biosynthesis? - Proteins - Phospholipids - ATP - Glucose - Nucleic Acids

- Proteins - ATP - Nucleic Acid

What factors can affect the doubling time of a bacterial cell?

- Temperature - Moisture - pH - Oxygen levels

Which type of microorganism derives nutrition from organic compounds?

Chemoheterotroph

Which term describes organisms that acquire their nutrients from other organisms or their waste products?

Chemotrophs

Which phase of bacterial growth involves more cells dying than reproducing?

Death

In which phase of bacterial growth are far more cells dividing than dying?

Exponential

Which term describes that require or tolerate high concentrations of salt?

Halophile

Which enzyme is NOT involved in DNA replication?

RNA polymerase

Pathogens usually have ____ doubling times.

Short

Identify essential functions of a living membrane.

- Block diffusion of proteins - Block the entrance of larger molecules

Which of the following are essential functions of a living membrane? - Block the entrance of larger molecules - Block the exit of water - Permit the exit of larger molecules - Permit free diffusion of proteins - Permit free diffusion of water

- Block the entrance of large molecules - Permit free diffusion of water

Which methods can be used to estimate the sizes of bacterial populations without culturing on plates?

- Completing a direct cell count - Analyzing the turbidity of a broth - Using a flow cytometer

Which best describes a parasitic relationship between microbe and host? - Wood-processing protozoa living in a termite gut - Flesh-eating bacteria on human skin - Escherichia coli bacteria growing in the human gut - Decomposing fungi living in soil around plants

- Flesh-eating bacteria on human skin

Which of the following are methods that count cells as they pass through a type of automated scanner?

- Flow cytometer - Coulter counter

Which of the following environmental factors are likely to have the greatest influence on microbial growth? - Gases such as carbon dioxide and oxygen - Pressures - pH - Temperature - Gases such as helium and argon - Rock formations

- Gases such as carbon dioxide and oxygen - Pressures - pH - Temperature

Which is FALSE regarding binary fission? - Like meiosis in eukaryotes, it specifically produces daughter cells with genetic variation. - Division involves the formation of a protein band that resembles actin and tubulin of eukaryotes. - Daughter cells are identical to each other. - It is a type of asexual reproduction.

- Like meiosis in eukaryotes, it specifically produces daughter cells with genetic variation.

Which of the following molecules require phosphorous for biosynthesis?

- Nucleic acids - ATP - Phospholipids

Which of the following describes how biofilms become resistant to many antibiotics?

- Some biofilm microbes can produce protective compounds to stop antibiotic activity and thereby protect the entire biofilm. - Peripheral microbes die and protect more internal microbes from harm.

A flow cytometer can provide which of the following types of data?

- The number of cells in a sample - Whether the cells in a sample are alive - Size of the cells in a sample

Which of the following types of radiation can damage microbes?

- Ultraviolet - Ionizing

Identify true statements concerning parasites. - Viruses are considered parasites. - Endoparasites live on the body surface - Obligate parasites can be cultured in the lab on artificial medial - Intracellular parasites live within cells

- Viruses are considered parasites. - Intracellular parasites live within cells

Put the following phases in order for a normal bacterial growth curve, beginning with the first at the top. - Death - Exponential - Lag - Stationary

1. Lag 2. Exponential 3. Stationary 4. Death

Place the following steps in order to demonstrate your understanding of the viable plate count. - Incubate the broth for a set time period. - Place a small number of cells into a sterile broth. - Take a sample from the broth and plate onto solid media. - Incubate all plates and count the colonies that develop.

1. Place a small number of cells into a sterile broth. 2. Incubate the broth for a set time period. 3. Take a sample from the broth and plate onto solid media. 4. Incubate all plates and count the colonies that develop.

Assuming you start with just one microbe and it could divide every 30 minutes, how many microbes would you have after 2 hours?

16

Identify the temperature range of thermophilic microorganisms.

45C to 80C

You ingest 20 cells of Salmonella. This bacterium has a doubling time of 30 minutes. After 4 hours, how many of these bacteria would be present in the body (assuming no immune system responses or other biological activities affect it's growth)?

5,120

Active transport differs from diffusion in that energy in the form of ____ is required.

ATP & proton motive force

Which name is given to microbes that grow in environments where the pH is lower than 7?

Acidophiles

What word is used to describe organisms which can use oxygen in their cellular respiration pathways?

Aerobic

A bacterial pathogen that can grow in pH 10 environments would be best described as a(n) ____.

Alkalinophile

Any microorganism that grows best in the absence of oxygen is a(n) ____.

Anaerobe

What term is used to describe organisms that can generate their own food from inorganic compounds?

Autotrophs

Hydrogen peroxide formed during aerobic respiration is converted to water and oxygen by the enzyme ____.

Catalase

A type of symbiotic relationship between two organisms in which one species derives benefit without harming the other is called ____.

Commensalism

A nutrient that must be obtained by an organism because it cannot be manufactures is called a(n) ____ nutrient.

Essential

Environmental factors control microbial growth through their influence on enzyme activity

False

True or False: Both human and bacterial cells divide by mitosis.

False

True or False: Cells cannot begin a new round of replication until they have completely finished dividing.

False

From which environment would you most likely observe growth of psychrophilic microorganisms? - Outside air in summer months - Frozen food - Water from a hot tub

Frozen Food

Which term describes the length of time a microbial species needs to divide?

Generation time

Which of the following would move across the cell membrane by facilitated diffusion?

Glucose

A graphical representation of the change in population size over time is called a(n) ____ curve.

Growth

Identify highly reactive, toxic byproducts of oxygen metabolism.

H2O2 (hydrogen peroxide) OH- (hydroxyl radicals) O2- (superoxide ion)

Which organism relies upon organic compounds for its carbon and energy needs?

Heterotroph

A solution what will cause a cell to lose water is termed ____.

Hypertonic

A solution that will cause a cell to swell with water is called ____.

Hypotonic

Where would a thermophilic microorganism be found?

In natural hot springs

Refrigeration will ____ the doubling time of most pathogens.

Increase

Which of the following would describe a solution which is well balanced for a cell?

Isotonic

Which of the following characterizes the lag phase of a normal bacterial growth curve?

Little increase of cell numbers

An aerobic bacterium that requires oxygen at a concentration less than that in the atmosphere is called a(n) ____.

Microaerophile

Identify bacteria that require higher than normal levels of carbon dioxide for isolation.

Neisseria; Streptococcus pneumoniae

Which of the following adjectives is often used to describe the absolute reliance of an organism on the presence of something else?

Obligate

What word describes a microbe that must have oxygen to survive?

Obligate aerobe

What term is used to describe the "best" temperature to support a microbe's growth?

Optimal temperature

A microorganism that thrives in any hypertonic medium is called a(n) ____.

Osmophile

The diffusion of water across a selectively permeable membrane in the direction of lower water concentration is called ____.

Osmosis

Prior to refrigeration, how did salting help preserve foods?

Osmotic pressure prevented growth of microbes

You leave your potato salad out on the table at the company picnic. When you made it, you unknowingly introduced 100 cells of Salmonella. How much time will it take for the population of Salmonella to reach at least one million if it's doubling time is 20 minutes at picnic conditions?

Over 4 hours

What name is given to relationships between organisms where one organism benefits at the expense of another organism?

Parasitism

A noun often used to describe organisms which can cause disease is a ____.

Pathogen

Any microbe that uses photosynthesis to feed is specifically referred to as a(n) _____.

Phototroph

Which term is used to describe organisms that use the sun's light to directly power their metabolic pathways?

Phototrophs

The cell actively engulfs liquids by extension of the cell membrane during the endocytic process of ____.

Pinocytosis

What type of bacteria will grow in the refrigerator, and why is this usually not a concern?

Psychrophiles; very few are pathogenic to humans.

Which term describes a heterotroph that decomposes organic remains from dead organisms?

Saprobe

Match each mineral ion with its role in the bacterial cell.

Sodium - Important for cell transport Magnesium - Component of chlorophyll Calcium - Stabilizes the cell wall Zinc - Component of DNA binding proteins

The phase of bacterial cell growth when the number of cells dividing equals the number of cells that are dying is the ____ phase.

Stationary

Bacterial oxygen tolerance patterns are determined by incubating a pure culture of a microorganism in ____ medium.

Thioglycollate

During binary fission, one bacterial cell becomes ____ cells.

Two genetically identical

A microbe that doesn't use oxygen at any time but is not harmed by it is described as a(n) ____ anaerobe.

aerotolerant

An organism that prefers alkaline pH (pH above 7) is called a(n) ____.

alkalinophile

The process by which one bacterial cell becomes two cells is termed ____.

binary fission

Some microbes live in mixed communities attached to a surface and are fairly resistant to antibiotics. These formations are called ____ and often grow on materials such as catheters.

biofilms

The movement of molecules along a concentration gradient by spontaneous random motion to achieve a uniform distribution is termed ____.

diffusion

When a cell suspension in a chamber is viewed under the microscope, enumeration of bacteria can be achieved by a(n) ____ cell count.

direct

A microbe's nutritional type (such as autotroph or phototroph) is determined by its sources of ______ and ______.

energy; carbon

Chemoautotrophic bacteria that rely on inorganic materials to supply their nutritional needs are known as ____.

lithoautotrophs

The highest temperature at which an organism will grow is called the ____ temperature.

maximum

The structure that regulates the transport of materials into and out of the cell is the cytoplasmic ____.

membrane

Most of the microbiota in the human body are classified as ____.

mesophiles

The largest group of medically important microorganisms are ____ bacteria that have an optimal growth temperature in the rand of human body temperature.

mesophilic

The lowest temperature at which an organism will grow is called the ____ temperate.

minimum

A symbiotic relationship between two organisms in which both species benefit is called ____.

mutualism

A(n) ____ is a microbe which prefers environments near or at a pH of 7.

neutrophile

Growth of a bacterial culture in growth medium in a test tube is defined as a closed culture, meaning that ____.

nutrients are limited and waste products are not removed.

A relationship between two organisms where the host is harmed and the colonizer benefits is called ____.

parasitism

The engulfment of large particles into vesicles within a cell is called ____.

phagocytosis

Microbes that use photosynthesis to derive their energy are classified as ____, while microbes that gain energy from oxidizing chemical compounds are classified as ____.

phototrophs; chemotrophs

Cells must _____ their DNA prior to cell division.

replicate

The FtsZ protein is needed to form the ____.

septum

A close partnership between individuals from two species that may be helpful, harmful, or neither to either member is called ____.

symbiosis

An interrelationship between two or more free-living organisms that benefits them but is not necessary for their survival is ____.

synergism

The coordination action between 2 microorganisms or drugs that results in a heightened response or greater effectiveness is called ____.

synergism

The energy source for contraction of the FtsZ ring during cell division comes from ____.

the hydrolysis of GTP

To obligate anaerobes, oxygen is ____ and ____.

toxic and not used

The term that describes the appearance of a cloudy broth culture is ____.

turbid

Match the data for a bacterial growth curve with the axis on which it is plotted.

x - time y - number of cells