UF MCB 3020 Exam 1

If the decolorizer is not left on long enough in the Gram-staining procedure, Gram-positive organisms will be stained _________ and Gram-negative organisms will be stained _________.

purple; purple

Which of the following microscopes typically uses dyes or antibodies?

Fluorescence microscope

Cells with a relatively complex morphology that have a true membrane-delimited nucleus are called _________

eukaryotes

Select a harmful effect that can result from bacterial colonization of the human body.

Invasion of host cells

Antiseptic surgery was pioneered by _________

Lister

Which of the following advances best describes the idea that today we may be experiencing a second golden age of microbiology?

Genomic testing

The instrument that produces a bright image of the specimen against a dark background is called a(n) _________

dark-field

Carl Woese distinguished between the members of the Archaea and the Bacteria using studies of their _________

ribosomal RNA

A microbe is discovered living in an extreme environment near a deep sea vent. The microorganism lacks a nucleus and peptidoglycan in its cell wall, but it does have unusual membrane lipids. This species is most likely a member of the Domain _________

Archaea

The concept that living organisms arise from nonliving material is called _________

spontaneous generation

The term used to describe bacteria that have a spherical shape is _________

coccus

Which of the following structures are external to both bacterial and archaeal cells?

Pili

The term used to describe bacteria that are rod-shaped is _________

bacillus

Flexible bacteria with a helical shape are called _________

spirochetes

All of the following statements about the periplasmic space are true except _________

it is found only in Gram-positive bacteria

The term used to describe bacteria that are shaped like curved rods is _________

vibrio

Which of the following is not true about archaeal ribosomes?

They have similar antibiotic sensitivities to those of bacteria.

Rigid bacteria with a helical cell shape are called _________

spirilla

Proteins are synthesized on structures called _________

ribosomes

Which of the following diseases is (are) caused by prions?

Scrapie

Mad cow disease

Kuru and Creutzfeldt-Jakob Disease

All of the choices are correct.

All of the choices are correct.

The liquid component of the cytoplasm is known as the _________

cytosol

Which of the following is a function of the mitochondrion?

Electron transport

All of the choices are correct.

ATP synthesis

Tricarboxylic acid cycle enzyme reactions

All of the choices are correct.

The Golgi apparatus is responsible for the _________

packaging of materials for excretion

The major site of cell membrane synthesis is the _________

endoplasmic reticulum

Which of the following is useful in distinguishing between bacterial, archaeal, and eukaryotic cells?

The use of DNA for the storage of genetic information

The presence of membrane-delimited organelles within the cytoplasm

All of the choices are correct.

The presence of ribosomes for the synthesis of proteins

The presence of membrane-delimited organelles within the cytoplasm

Which of the following organelles is involved in the modification, packaging, and secretion of materials?

Golgi apparatus

The proper sequence of reagents in the Gram stain procedure is _________

crystal violet, iodine, ethanol, safranin

After performing a Gram stain of a mixed culture of Gram-positive and Gram-negative cells, you realize you forgot to apply the iodine in step 2. What would you expect to see if you observed the slide under the microscope after this omission?

Pink Gram-positive and pink Gram-negative cells

The Gram stain of a bacterial cell is based on the chemical properties of its _________

cell wall

Acetone can be used as the decolorizer in the Gram stain procedure. T/F

True

The Gram stain can only be performed on cultures grown in liquid media. T/F

False

In the Gram-staining procedure, the mordant is _________

iodine

In the following list of scientists who provided the evidence needed to discredit the concept of spontaneous generation?

Pasteur

In the Gram-staining procedure, the counterstain is _________

safranin

A newly discovered unicellular microbe has a nucleus containing linear chromosomes and is surrounded by a membrane. It has mitochondria, 80s ribosomes, and is covered by cilia. There is no cell wall external to the plasma membrane. This organism most likely would be a/an _________

protozoan

The nucleolus plays a major role in synthesis of _________

rRNA

Prior to staining, smears of microorganisms must be heat-fixed in order to _________

attach them firmly to the slide

Although developed over 100 years ago, Koch's postulates continue to be used to find the causative organism for all known human infectious diseases. T/F

False

In the following list of scientists, who developed a set of criteria that could be used to establish a causative link between a particular microorganism and a particular disease?

Koch

Viruses are not generally studied by microbiologists because they are not classified as living organisms. T/F

False

A strain of Neisseria gonorrhoeae has undergone a mutation and is no longer able to make pili. Predict the most likely outcome.

The bacteria will become less virulent and will not be able to readily establish infection.

After the primary stain has been added but before the decolorizer has been used, Gram-positive organisms are stained _________ and Gram-negative organisms are stained _________.

purple; purple

The instrument that produces a bright image of the specimen against a dark background is called a(n) _________ microscope.

dark-field

Scientists study microorganisms on Earth today to search for life forms elsewhere, as well as to explore the origins of life on Earth. These microorganisms that are studied are referred to as _________

extant

Chemotaxis is a process by which bacteria _________

move toward an attractant or away from a repellent

The most important distinguishing feature of eukaryotes that is lacking in bacteria and archaea is _________

the division of the cell into compartments that are bound by membranes

External structures that are found in archaea but not bacteria are _________

hami

The genetic code is expressed differently in bacterial and archaeal cells than in eukaryotic cells. T/F

False

According to the endosymbiosis hypothesis _________

the mitochondrion evolved from the same endosymbiont as the hydrogenosome

the first endosymbiont was a fermentative organism

All of the choices are correct.

the first endosymbiotic event involved an anaerobic bacterium

All of the choices are correct.

A(n) _________blank is a special type of lysosome used by a cell to selectively digest and recycle cytoplasmic contents, such as mitochondria.

autophagosome

Archaeal and bacterial pili are identical in structure and function. T/F

False

Protein filaments with a diameter of 4-7 nm that play a role in cell movement and shape change are called _________

microfilaments

Each of the following provides evidence in support of the primary role of RNA in the evolution of life EXCEPT _________

RNA is less chemically stable than DNA

The organelle responsible for harvesting light as an energy source for photosynthesis is the _________

chloroplast

The endoplasmic reticulum is composed of flattened sacs called _________

cisternae

A fundamental difference between bacterial and archaeal membranes is that _________

bacterial membranes are always comprised of phospholipid bilayers, whereas archaeal membranes can be bilayers or monolayers

RNA is a key intermediate molecule involved in the process that uses the information stored in DNA to ultimately produce _________

proteins

Gram-positive bacteria have a structurally and chemically more complex cell wall than Gram-negative bacteria. T/F

False

Twitching motility involves _________

type IV pili

Which cell type ranges in size from about 10-100 µm, has 80s ribosomes, and has internal compartments bounded by membranes?

Eukarya

Some microorganisms are useful in bioremediation processes that reduce the effects of pollution. T/F

True

If the decolorizer is left on too long in the Gram-staining procedure, Gram-positive organisms will be stained _________ and Gram-negative organisms will be stained _________

pink; pink

You are studying a newly discovered prokaryotic microorganism and are attempting to determine whether it will be classified in the domain Bacteria or in the domain Archaea. All of the following would be helpful in making that distinction except _________

presence or absence of double-stranded circular DNA genome

Select the correct statement about archaeal ribosomes.

The chemical components of archaean ribosomes are more similar to those of eukaryotic ribosomes than to those of bacterial ribosomes.

Which of the processes named here is the least likely to contribute to the evolution of genetic diversity of bacteria and archaea?

Sexual reproduction

After the mordant has been added, Gram-positive organisms are stained _________ and Gram-negative organisms are stained _________.

purple; purple

A newly discovered microorganism has a circular chromosome that is complexed with histones but not enclosed within a membrane. The plasma membrane lipids include glycerol dietethers and diglycerol tetraethers. There are no mitochondria or chloroplasts, but the cells do contain 70s ribosomes. This microbe most likely is _________

an archaeon

In the following list of scientists who was the first to observe and accurately describe microorganisms?

van Leeuwenhoek

A student is observing microorganisms in a sample of pond water. One organism of interest has an obvious nucleus, small oval structures containing a green pigment, and does not appear to be motile. In which of the following groups would this microbe most likely be classified?

Eukaryotes (Algae)

If you remove the peptidoglycan layer from a Gram-positive cell, it would still stain purple with a Gram stain. T/F

False

Lysosomes are membrane-bound vesicles that arise from the _________

Golgi apparatus

The lysosome contains _________ enzymes.

hydrolyticCorrect

Which of the following cells will be expected to contain the most active lysosomes?

Phagocytosing white blood cell

Lysosomes function in the destruction and recycling of old organelles. T/F

True

The enzymes found in lysosomes were synthesized by ribosomes located on the endoplasmic reticulum. T/F

True

The abnormal form of the protein is designated _________.

PrPSc

Prions cause _________ diseases.

neurodegenerative

A harmless PrP is converted into the infective PrP _________.

by an abnormal PrP that binds to the normal protein and causes it to become misfolded

Disease symptoms are believed to be the result of dense aggregates of the abnormal protein. T/F

True

In some inherited cases, the normal prion protein can convert spontaneously to the abnormal form, but at a slow rate. T/F

True