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Microbiology Unit 2 test
Crowder College Micro Unit 2
96
Biology
10/09/2011

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Term
Define metabolism.
Definition
the sum of all the chemical reactions within a living organism.
Term
5 properties of catabolism
Definition

1) break down complex organic compounds to simpler ones

2) Degradation reactions

3) Generally hydrolysis reactions

4) Enzyme regulated chemical reactions

5) Exergonic reactions (energy-releasing)

Term
5 properties of anabolism
Definition

1) building complex organic compounds from simpler ones

2) Biosynthesis reactions

3) Generally dehydration synthesis reactions

4) Enzyme regulated chemical reactions

5) Endergonic reactions (energy-requiring)

Term
What is ATP made of?
Definition
Adenine, ribose, and 3 phosphate groups
Term
What is a metabolic pathway and what is it determined by?
Definition

A sequence of enzymatically catalyzed chemical reactions in a cell.

Enzymes

Term
Enzymes increase the rate of reaction by?
Definition
Decreasing the activation energy needed.
Term
What are the two components of an enzyme?
Definition

Apoenzyme-protein, inactive

Cofactor-non-protein component, activator

Term
List four factors influencing enzyme activity.
Definition

1) Temperature

2) pH

3) Substrate concentration

4) Enzyme inhibitors-prevent the substrate from binding to the active site of the enzyme (competitive and noncompetitive)

Term
What is the best temperature for bacterial enzyme activity?
Definition
37 degrees C
Term
What is the best pH for bacterial growth?
Definition
7
Term
T/F--When all the enzyme molecules are in use, adding more substrate does not increase the enzyme activity.
Definition
True
Term
Define competitive inhibition.
Definition
Competitive inhibitor binds to the active site of the enzyme and prevents the substrate from binding.
Term
Define noncompetitive inhibition.
Definition
Inhibitor binds to allosteric site and alters the shape of the active site.  This prevents the substrate from binding to the active site.
Term
Oxidation is?
Definition
The removal of electrons
Term
Reduction is?
Definition
The gain of electrons.
Term
Redox reaction is?
Definition
An oxidation reaction paired with a reduction reaction.
Term
What is phosphorylation?
Definition
The addition of a phosphate group to a chemical compound.  ATP is generated by the phosphorylation of ADP.
Term
What is chemiosmosis?
Definition
when energy released from the transfer of electrons (oxidation) of one compound to another (reduction) is used to generate ATP from ADP.
Term
What are the three cycles of carbohydate metabolism?
Definition

1) glycolysis

2) Kreb's cycle

3) Electron transport chain

Term
Define glycolysis.
Definition
the oxidation of glucose to pyruvic acid, produces ATP and NADH
Term

What is the net gain and the end product from glycolysis?

 

Definition

Net gain: 2 ATP molecules

End product: pyruvic acid

Term
What is another name for glycolysis?
Definition
Embden-Meyerhof pathway
Term
What are the two alternative pathways to glycolysis?
Definition

1) Pentose phosphate pathway

2) Entner-Doudoroff pathway

Term
Describe the Pentose phosphate pathway.
Definition

1) operates with glycolysis

2) net gain: 1 ATP

3) uses pentoses and produces NADPH

examples: Bacillus subtilis; E. coli

Term
List four properties of the Entner-Doudoroff pathway.
Definition

1) Produces NADPH and 1 ATP

2) does not involve glycolysis

3) generally found in gram-negative bacteria, i.e. Pseudomonas, Rhizobium, Agrobacterium

4) generally not found in gram-positive bacteria

Term
Describe the two types of cellular respiration.
Definition

Aerobic respiration-final electron acceptor is oxygen

Anaerobiv respiration-final electron acceptor is an inorganic molecule

Term
Pyruvic acid from glycolysis is converted to?
Definition
Acetyl Coenzyme A
Term
What are two other names for the Kreb's cycle?
Definition

1) Tricarboxylic acid (TCA) cycle

2) Citric acid cycle

Acetyl coenzyme A enters the Kreb's cycle

NADH and 2 molecules of ATP are produced

Term
Describe an electron transport chain.
Definition

A series of carrier molecules are, in turn, oxidized and reduced as electrons are passed down the chain.  

First step: transfer electron from NADH

Oxygen: last electron acceptor

Energy released can be used to produce ATP by chemiosmosis.

Term
Name and describe the three classes of electron carriers.
Definition

1) flavoproteins (proteins+flavin)

2) cytochromes (proteins+iron)

3) ubiquinones or coenzyme Q (non-protein)

Term
T/F--Anaerobic respiration yields more energy than aerobic respiration because only part of the Kreb's cycle is in operation.
Definition
False
Term
In eukaryotic cells the electron transport chain takes place in the?
Definition
Inner membrane of mitochondria.
Term
In prokaryotic cells, the electron transport chain takes place in the?
Definition
Plasma membrane of the cell.
Term
How much ATP is produced from complete oxidation of one glucose using aerobic respiration in prokaryotes and eukaryotes?
Definition

Prokaryotes: 38 ATP molecules (2+2+34)

Eukaryotes: 36 ATP molecules (2+2+32)

Term
List 5 properties of fermentation.
Definition

1) Releases energy from oxidation of organic molecules

2) Does not require oxygen; can take place in the absence or presence of oxygen

3) Does not use the Kreb's cycle or ETC

4) uses an organic molecule as the final electron acceptor

5) 1 or 2 ATP molecules are made

Term
Alcohol fermentation produces?
Definition
ethyl alcohol+CO2
Term
What are the two types of lactic acid fermentation and what do they produce?
Definition

Homolactic fermentation: lactic acid only

Heterolactic fermentation: lactic acid and other compounds

Term
Define deamination.
Definition
getting rid of an amino group
Term
Define decarboxylation.
Definition
Getting rid of a carboxyl group
Term
Define dehydrogenation.
Definition
Getting rid of hydrogen.
Term
What are the classifications of bacterial nutrition patterns?
Definition

Phototrophs: sun light for energy

Chemotrophs: chemicals for energy

Autotrophs: self-feeders

Heterotrophs: other feeders

Term
Bacteria use polysaccharide biosynthesis for?
Definition
The peptidoglycan cell wall
Term
Bacteria use lipid biosynthesis for?
Definition
waxes, cell wall of acid-fast bacteria, caratinoids: red, orange, yellow pigments
Term
Bacteria use amino acids and protein biosynthesis for?
Definition
Peptidoglycan cell wall
Term
Polysaccharide biosynthesis occurs during?
Definition
Glycolysis
Term
Lipid biosynthesis occurs during?
Definition
Glycolysis and the intermediate step
Term
Amino acid and protein biosynthesis occur during?
Definition
Alternative pathways and the Kreb's cycle
Term
Define transanimation.
Definition
When an amino group comes from an existing amino acid.
Term
Define amination.
Definition
Amino group comes from a molecule other than an amino acid.
Term
Purine and pyrimidine biosynthesis occurs during?
Definition
glycolysis and the Kreb's cycle
Term
Describe amphibolic pathways.
Definition

1) metabolic pathways that have both catabolic and anabolic functions

2) anabolic and metabolic reactions are joined through a group of common intermediates

3) these pathways can be seen in glycolysis and Kreb's cycle

Term
Define microbial growth.
Definition
Increase in number of cells, not cell size.
Term
List three physical requirements for growth.
Definition

1) temperature

2) pH

3) osmotic pressure

Term
What are the chemical requirements for microbial growth?
Definition

1) source of C, N, S, P trace elements

2) oxygen, organic growth factors

Term
What are the five classifications of microbes according to growth due to temperature?
Definition

1) Psychrotrophs: 0-30 degrees C, cause food spoilage

2) Psychrophiles: cold-loving

3) Mesophiles: moderate temperature loving

4) Thermophiles: heat-loving microbes

5) Hyperthermophiles: 70-110 degrees C

Term

Bacteria grow in what pH?

Molds and yeast?

Definition

Bacteria: 6.5-7.5

Molds and yeast: 5-6

Acidophiles: acid-loving bacteria

Term
Hypertonic environments (increase in salt or sugar) cause?
Definition
Plasmolysis (shrinkage of cell's cytoplasm) which will inhibit cell growth
Term
Extreme or obligate halophiles require what?
Definition
High osmotic pressure: Dead sea-30% salt
Term
T/F--Facultative halophiles require high osmotic pressure (2-15% salt).
Definition
False: they tolerate, but do not require high osmotic pressure
Term
Define obligate aerobes.
Definition
organisms that require oxygen to live
Term
Define facultative anaerobes.
Definition
Aerobic bacteria that can continue to grow in the absence of oxygen by using fermentation or anaerobic respiration.
Term
Define obligate anaerobes.
Definition
Unable to use oxygen, most are harmed by it.
Term
Define aerotolerant anaerobes.
Definition
cannot use oxygen, but they tolerate it
Term
Define microaerophiles.
Definition
Require oxygen in low concentrations.
Term
What enzyme is used to convert toxic forms of oxygen to non-toxic forms?
Definition
superoxide dismutase (SOD)-not produced by obligate anaerobes
Term
Define culture medium.
Definition
Nutrients prepared for microbial growth.
Term
Define sterile.
Definition
No living microbes present.
Term
Define inoculum.
Definition
Introduction of microbes into medium.
Term
List five propeties of agar.
Definition

1) complex polysaccharide

2) used as solidifying agent for culture media in petri plates, slants and deeps

3) generally not metabolized by microbes

4) liquefies at 100 degrees C

5) solidifies at about 40 degrees C

 

Term
Define chemically defined media.
Definition
Exact chemical composition is known.
Term
Complex media contains:
Definition

Extracts and digests of yeasts, meat or plants

Example: nutrient broth, agar

Term
Describe anaerobic media.
Definition
Used to grow anaerobes; contains chemicals that remove oxygen molecules from the media
Term
Describe selective media.
Definition
Selects or allows growth of one type of bacteria and inhibits growth of others
Term
Describe differential media.
Definition
Allows growth of many types of bacteria, but differentiates them by color changes in the media or growth itself
Term
Phenyl Ethyl alcohol agar (PEA agar) is what type of media?
Definition
selective media; prevents growth of gram-negative bacteria by dissolving the outer membrane of the cell wall
Term
Phenol red fermentation tubes are what type of media?
Definition

Differential; if bacteria ferments the carbohydrate to acid while growing, the media will turn yellow

if bacteria cannot ferment the carbohydrate to acid while growing, media will stay red

Term
In blood agar, a differential media, how are hemolytic bacteria differentiated from non-hemolytic bacteria?
Definition
Hemolytic bacteria while have a clear ring or halo around them.
Term
Mannitol salt agar (MSA) and Eosin Methylene Blue agar (EMB) are what type of media?
Definition
Combined: inhibits growth of unwanted bacteria and selects for the desired bacteria to grow; can differentiate the bacteria that are growing using biochemical characteristics
Term
How do bacteria reproduce?
Definition
Binary fission
Term
Define generation time.
Definition
the time that bacteria needs to divide into two or the time between cycles
Term
What do p, m and n stand for in the equation p=mx2n?
Definition

p=# of cells in a population

m=# of cells at the beginning

n=# of generations

Term
List and describe the four phases of bacterial growth.
Definition

Lag phase: little or no growth

Log phase: exponential growth; sensitive to adverse conditions

Stationary phase: slow growth rate; stabilized population

Death phase: decline phase; cells die in a logarithmic scale

Term
What three things can cause exponential growth to stop?
Definition

1) Lack of sufficient nutrients: with time bacteria will use up all the nutrients in the media

2) Accumulation of waste: with time bacteria can produce toxic substances, acids that can inhibit growth

3) Changes in pH

Term
List and describe the three direct methods of measuring bacterial growth.
Definition

1) Plate counts: each colony represents a bacterial cell in the original sample

2) Filtration: useful when the original sample has very small number of bacterial cells

3) Direct microscopic count: count the number of bacterial cells directly using the microscope

Term
List and describe three methods of indirectly estimating bacterial numbers.
Definition

1) Turbidity: indicates the amount of bacteria growing in the medium; more turbid means more bacteria; measured using spectrophotometer

2) Metabolic activity: amount of acid production or CO2 production indicates the amount of bacteria growing in the medium

3) Dry weight: bacteria are removed from the growth medium and dried in a desiccator and weighed

Term
What are four factors affecting antimicrobial treatment?
Definition

1) Number of microbes

2) Environment

3) Time of exposure

4) Microbial characteristics

Term
List and describe three actions of microbial control agents.
Definition

1) Damage to proteins and lipids in the plasma membrane causes cellular contents to leak

2) Damage to the cell wall: denatures the proteins so they can no longer function in the cell wall

3) Damage to nucleic acids: cells can no longer replicate

Term
What are the three types of microbial control using heat?
Definition

Moist heat: denatures proteins

Dry heat: oxidation

Pasteurization: 63 degrees C for 30 min or 72 degrees C for 15 seconds-sterilization (stored without refrigeration) 140 degrees C for <1 second

Term
Effective disinfection depends on what four factors?
Definition

1) the concentration of the disinfectant

2) organic matter contaminations

3) pH of the disinfectant

4) time exposed to disinfectant

Term
 Describe phenols
Definition
Carbolic acid; Lysol denatures proteins
Term
Describe halogens.
Definition
Oxidizing agents; denatures proteins; iodine, chlorine
Term
Describe alcohols as disinfectants.
Definition
Denatures proteins, dissolve lipids; kills bacteria and fungi, but not endospores and noenveloped viruses; 70% alcohol is the most effective
Term
Descibe heavy metals as disinfectants.
Definition
Oligodynamic action; denatures proteins; Ag, Hg, Cu
Term
How do soaps and detergents help in disinfecting?
Definition
Degerming and sanitizing; little value as antiseptics, but help in mechanical removal of microbes
Term
Describe aldehydes.
Definition
Denature proteins; inactivate proteins by cross-linking with functional groups
Term
Describe peroxygens.
Definition
Oxidizing agent; O3 used in disinfection of water; H2O2 used as antiseptic but not for open wounds; peracetic acid