Define microbe

Cellular entity that is not a component of a tissue or similar structure as that which comprises metazoans.

T/F: Microbes are generally only able to be seen with the aid of a microscope

True

T/F: Microbes are visible to the naked eye when they form aggregations such as a biofilm or a colony.

True

T/F: Microbes are found among the domains Eukarya, Bacteria, and Archaea.

True

T/F: Microbes include viruses which are not considered cells.

True

T/F: Microbes and/or microbial activities are involved in the decomposition of organic matter in the soil.

True

T/F: Microbes and/or microbial activities are involved in water treatment plants.

True

T/F: Microbes and/or microbial activities are involved in the production of vaccines and antibiotics.

True

T/F: Microbes and/or microbial activities are involved in many biotechnology applications.

True

You are observing a cell through a light microscope and note that it has no apparent nucleus. You conclude that it most likely...

is either a bacteria or archaea

T/F: Regarding Pasteur's experiments with the S-neck flask, there was air involved

True

T/F: Regarding Pasteur's experiments with the S-neck flask, there was a food source involved

True

T/F: Regarding Pasteur's experiments with the S-neck flask, all microorganisms were killed before the beginning of the experiment

True

T/F: Regarding Pasteur's experiments with the S-neck flask, any possibility of contamination was removed.

True

T/F: In order to establish that a certain bacterium causes disease, it is necessary to obtain a pure culture of the bacterium from an infected animal

True

T/F: In order to establish that a certain bacterium causes disease, it is necessary to inject a healthy animal with a pure culture of the suspected bacterium

True

T/F: In order to establish that a certain bacterium causes disease, it is necessary to show that the bacterium is not present in healthy animals

True

T/F: In order to establish that a certain bacterium causes disease, it is necessary to perform a Gram stain on the bacterial cells

False

T/F: In order to establish that a certain bacterium causes disease, it is necessary to show the same bacterium is isolated from infected animals

True

What are Chemolithotrophs?

Soil bacteria discovered by Winogradsky; capable of using inorganic molecules as energy sources.

T/F: Resolution can be improved by using a longer wavelength of light

False

T/F: Resolution can be improved by using a lens with high value of numerical aperture

True

T/F: Resolution can be improved by using immersion oil and the oil immersion objective lens

True

T/F: Resolution can be improved by improving contrast by use of a stain or other method

True

Which microscope has similar resolution to the light microscope, does not require staining of the sample, allows one to view cells in their living state, and takes advantage of differences in the refractive indexes of cell structures to provide contrast?

Phase-contrast microscope

Total magnification=

(Objective lens magnification) x (ocular lens magnification)

What is the purpose of the parabolic surface of the objective lens?

refracts light that then meets at a focal point

What enables lenses to magnify an image?

Refraction

What enables selective labeling of cellular structures with light emitting dyes?

Fluorescence microscopy

What will typically stain some cells one color and other cells another color?

A differential stain

In comparing light microscopy with electron microscopy, one would employ the:

(Q11)

T/F: Electron microscopy has a resolution about 1000X greater than a light microscope

True

For electron microscopy, ________rather than lenses are used to focus the beam of electrons.

Magnets

T/F: Live specimens are not able to be observed by electron microscopy

True

T/F: For electron microscopy, scanning EM reveals the surface features of a specimen

True

What are prokaryotic cell membranes comprised of?

Phospholipids and proteins

Gram_______ bacteria have two phospholipid-containing membranes

negative

What are Hopanoids?

Small hydrophobic molecules that serve to reinforce the phospholipid bilayer

__________ are prokaryotes whose phospholipid fatty acid structure differs from otherprokaryotes

Mycobacteria and Archaea

List components of peptidoglycan

N-acetylglucosamine,

N-acetylmuramic acid,

amino acids,

peptide cross-links

Lipid inclusions contain_________.

poly-hydroxybutyrate (PHB) or poly-hydroxyalkanoate (PHA)

What do Magnetosomes enable cells to do?

orient themselves directionally, i.e., north/south

Gas vacuoles are a feature of ________.

aquatic bacteria

Carboxysomes are found in __________.

bacteria that utilize carbon dioxide

Fimbriae and Pili are generally used for__________.

attachment, not motility.

T/F: Specialized pili are used used for DNA transfer between bacterial cells

True

Counterclockwise flagellar movement results in________.

smooth forward motion

T/F: Flagellar motion in a bacterium occurs in a wave-like motion like a eukaryotic flagellum

False

T/F: When a bacterium is tumbling it is not moving in any particular direction and stops.

True

Stalk formation in certain bacteria results in____________.

immobilization of the cells in their environment.

Archaea have cell walls that are not made of peptidoglycan, but rather of a similar structure called___________.

pseudomurein

A____________ is a polysaccharide layer that is only loosely associated with the exterior of the cell

slime layer

T/F: The periplasmic space is an area that lies outside of the LPS layer of Gram-negative cells

False

_____________ follows DNA replication in bacteria and is where new cell wall synthesis occurs.

Septum formation

What are specific nutrients that a cell cannot make and must obtain from its environment?

(Q20)

If you prepared a liquid (aqueous) growth media containing mineral salts, trace elements, no organic carbon source, and light you would be selecting for________.

Photoautotrophs

The formation of a mother cell, the production of dipicolinic acid, asymmetric septation are all part of which process?

endospore formation

T/F: A fed batch culture will grow indefinitely

False

T/F: The best method for determining viable cell numbers in a sample is to ____________.

dilute the sample and do the spread plate method.

T/F: Differential media allows one to visualize different biochemical properties among bacteria.

True

The____________ transports molecules into the cell then phosphorylates the molecule, thereby maintaining the gradient to allow more molecules to move inside

phosphotransferase system (PTS)

___________ are the prominent flora beneath icebergs in the arctic and antarctic.

Pyschrophilic bacteria

Exposure to temperatures above 40-45C will trigger the heat shock response in___________.

mesophilic bacteria

The fastest growth rate for a species occurs at temperatures where___________.

a cell's proteins work most efficiently

____________ possess features that allow their proteins and cell membranes to function at high temperature.

Thermophiles

T/F: Eukaryotic cells are generally as heat tolerant as bacteria

True

(Q29)

List enzymes that help protect cells from damage caused by reactive oxygen species (superoxide radical, hydroxyl radical)

Catalase, SOD, and peroxidase enzymes

Concerning catalase, SOD, and peroxidase enzymes, __________ have only some, or none of these protective enzymes.

Anaerobic bacteria

Concerning catalase, SOD, and peroxidase enzymes, an __________ typically has all of these enzymes.

obligate aerobe

T/F: Antiseptics are of higher strength since they are used for cleaning of inanimate objects; disinfectants are used on living tissue such wound cleaning or surgical preparation.

False

Gases like ethylene oxide are effective in sterilizing_____________.

areas that are difficult to penetrate with liquid antimicrobials

T/F: Probiotics are antibiotics used to eliminate certain groups of bacteria from the gut.

False

Organisms adapted to grow at overwhelmingly high pressures are called___________.

barophiles

By themselves, heterorophs would deplete the world of__________ sources and starve to death.

organic carbon

During respiration, electrons (originating from cytoplasmic reductions) are______________.

passed through carriers of increasing reduction potential

Anaerobic respiration is the use of______________.

an alternative electron acceptor in respiration (i.e., anything other than oxygen)

Define nitrification.

the complete reduction of nitrate to N₂ during anaerobic respiration

This atmospheric gas is produced from the reduction of an alternative terminal electron acceptor in microbial respiration.

N₂

The proteins of the electron transport systems are usually_____________.

located within a membrane where they can produce a transmembrane ion gradient

Why is a large amount of energy is released when oxygen accepts electrons?

because oxygen is a strong electron acceptor/oxidizing agent

Define cofactors

Small molecules that associate with the protein

Many of the redox centers that comprise the electron transport system (ETS) are integral components of larger protein complexes, whereas others, such as_______, freely diffuse within the membrane as they ferry electrons between other ETS components.

quinones

During___________redox reactions happen in the cytoplasm and ATP is generated via substrate-level phosphorylation.

fermentation

What is the most likely explanation for the high numbers of sulfate reducers present in marine environments?

Sulfate is a very abundant anion in seawater, second only to chloride

Arrange the following items in the order in which they receive electrons from glycolysis and TCA oxidations and harness the energy to establish a transmembrane proton gradient.

1. NAD⁺

2. Oxidoreductase

3. Quinone

4. Terminal oxidase

5. Oxygen

The relationship between the reduction potential, E, and the change in free energy, ΔG is such that if E is __________, then ΔG is __________ and the reaction is __________.

positive; negative; favorable

For what process are the electrons from glycolytic reactions returned to the partially oxidized food source instead of being passed through an ETS system to a terminal electron acceptor.

fermentation

What processes contribute to the proton motive force during aerobic respiration?

TCA cycle, glycolysis, electron transport system

What determines which electron donor and electron acceptor a given microbe uses in its anaerobic ETS?

The available donors and acceptors will induce gene expression of their redox enzymes, thereby allowing their use.

The earliest life forms on our planet may have used which electron acceptor?

Fe³⁺

T/F: Autotrophs comprise only those types that can use light energy, i.e. photosynthesize

False

What are the types of autotroph?

photoautotrophs and chemoautotrophs

Though not all members of this kingdom fit into one of the following 3 groups, many can be categorized as being methanogens, halophiles, or thermophiles, including hyperthermophiles

Archaea

An attenuated strain of a pathogenic bacteria or virus provided to a person__________.

may prevent disease in the individual by later exposure too a more virulent form of the strain

Pasteur's work with the french wine industry proved what?

• That microbes are responsible for the chemical processes that produce wine
• Microbial growth and metabolism can occur in the absence of air
• The formation of acetic acid during wine production was due to the presence of contaminating microbes

T/F: Pasteur's work with the french wine industry proved that microbes can cause disease

False

T/F: Viruses are considered cells

False

Though changes were made later, the__________was originally formed to contain all microorganisms

Kingdom Protista

The evolution of_________allowed for later evolution of cells with an aerobic metabolism

Cyanobacteria

The__________contains the peptidoglycan layer of gram-negative bacteria

periplasmic space

Crystization of membrane phospholipid fatty acids (like cyclopropane) would confer_____________.

more rigid straighter hydrocarbon chains

Polysome formation in bacteria is able to occur because_____________.

They lack a nuclear membrane

What serves to help maintain the shape of the cell?

Bacterial cytoskeleton element MreB

What yields a high quantity of polypeptide in a short time interval?

Polysome formation

What is duplicated in the initial stage of DNA replication?

Ori sequence

What is a loose, unorganized assemblage of polysaccharide-protein material secreted by a bacterium that surrounds the cell.

Slime layer

Who discovered lithotrophic bacteria?

Winogradsky and Beijerinck

Who performed experiments with the swan necked flask?

Louis Pasteur

What did Louis Pasteur use the swan necked flask to show?

Oxygen does not allow spontaneous generation

The most abundant molecule in the cell is___________.

water

A second, outer membrane is found in____________.

Gram-negative bacteria

Aspirin, like many pharmaceutical drugs, can access the cell because it is a weak acid. This occurs because_____________.

As a weak acid it can cross the membrane when in its uncharged form.

Bacteria carry out bidirectional replication of their single chromosome by using_____replisomes that each contain______DNA polymerase enzymes.

2;2

How many different cellular components are in Gram-negative bacterium?

4

What are metachromatic granules?

Energy storage granule

What are sulfur granules a product of?

phototrophic or lithotrophic bacteria

Which of the following specialized structures/inclusion would aquatic photoautotrophic bacteria likely possess?

Thylakoids, Carboxysomes, and Gas vacuoles

What are thylakoids?

Membrane-bound compartments inside chloroplasts and cyanobacteria. They are the site of the light-dependent reactions of photosynthesis.

The carboxysome is likely found in__________.

an autotroph

What is the H antigen?

The slender threadlike portion of the flagellum

Counterclockwise rotation of flagella/flagellum produces__________.

runs toward an attachment

What can produce a type of motility involving intermittant attachment?

fimbrae/pili

What can the Enter-Douderoff pathway, the Embden-Meyerhof-Parnas pathway, and the Pentose Phosphate shunt all do?

Oxidize glucose to different intermediates and generate NADH and/or NADPH

Are catabolic processes exothermic or endothermic?

Exothermic

What type of process leads to the formation of smaller mmolecules from larger, complex molecules.

Catabolic processes

Food sources for catabolism supply___________; the energy from these is ultimately used to form ATPs.

electrons

Glycolysis inititially requires energy input in the form of_________.

ATP hydrolysis

Glycolysis forms ATP via_____________.

substrate level phosphorylation

What does glycolysis yield?

ATP and NADH

What is an example of anabolism?

DNA replication

What is anabolism?

The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism.

Lactic acid fermentation is so named because lactic acid is which of the following?

end product

During lactic acid fermentation, NADH reduces ________to________.

pyruvate;lactic acid

If a small molecule is found at greater concentration inside the cell than outside, it can be concluded that____________.

energy was required to produce the concentration gradient.

In addition to generating reducing power (i.e., NADPH) for biosynthesis, the pentose phosphate pathway also provides precursors for synthesis of which of the following?

nucleic acids, aromatic amino acids

If one molecule of glucose were fully catabolized via aerobic respiration to CO₂ and H₂O, the ATP yield would be roughly times______that obtained from fermentation.

20

Ethanolic fermentation results in what end product(s)?

alcohol and carbon dioxide

The breakdown of starch is a________process carried out by_________?

catabolic; bacteria

What is important for catabolism of sugars? respiration, fermentation, or both?

Both

What is the main electron carrier for both respiration and fermentation?

NADH

What is a major intermediate for both respiration and fermentation?

Pyruvate

A high ATP yield (most from oxidative phosphorylation) is a characteristic of what?

Respiration

Most carbon being released as CO₂ is a characteristic of what?

Respiration

Electrons reducing an external electron acceptor (e.g., O₂), is a characteristic of what?

Respiration

A low ATP yield (primarily from glycolysis) is a characteristic of what?

Fermentation

Electrons from catabolism ending up back on partially oxidized substrate is a characteristic of what?

Fermentation

Reactions that oxidize the organic materialhave a________H and a________∆S.

negative; positive

Why does the process of acquiring nutrients from a more dilute external environment require expenditure of energy by the cell?

Entropy is decreased.

Fermentation pathways have the __________ in common.

oxidation of NADH to NAD⁺

Bioremediation of certain pollutants (such as aromatic hydrocarbons) may be effectively accomplished via syntrophy, involving__________.

different species of microbes catalyzing sequential reactions.

Define Syntrophy

A relationship involving exchange of nutrients.

What pathway would be fully operational only in respiring bacteria?

TCA cycle

What are Mycoplasma?

Bacterial species that lack a cell wall.

What are mycolic acids?

Unusual cell wall components of mycobacteria species

What bacteria are unable to grow in the complete absence of oxygen?

Microaerophiles

The aggregation of cells, attachment to a surface, and formation of an extracellular polysaccharide miatrix are all part of which process?

biofilm formation

Define generation time

The length of time needed for a cell to divide.

Determining the nutritional requirements of a particular bacterial species is best determined by____________.

the length of time needed for the cell to divide

The reactions that extract energy from molecules like glucose are called____________.

catabolic reactions

____________refers to all of the metabolic reactions that build or assemble more complex molecules from simpler ones.

Anabolism