MCB3020 Final Review

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

True

The Gram stain can only be performed on cultures grown in liquid media

False

Eukaryote

An organism characterized by having cells containing DNA in a membrane-bound organelleP

Prokaryote

An organism characterized by having a cell lacking a membrane-bound nucleus

Prion

An infectious agent consisting of only protein

Viroid

An infectious agent consisting of only RNA

Virus

An infectious agent made up of protein, nucleic acids, and sometimes a lipid membrane

Antiseptic surgery was pioneered by

Lister

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

Pasteur

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

A. Mutation

B. Sexual Reproduction

C. Binary fission

D. Horizontal Gene transfer

Sexual Reproduction

Microbiologists study a variety of organisms, but all are considered either Bacteria or Archaea

False

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

vibrio

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

Proteins

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

chloroplast

The nucleolus plays a major role in synthesis of

rRNA

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

False

In the Gram-staining procedure, the mordant is

Iodine

If you forgot to heat fix a smear before doing a Gram stain, which of the following might occur?

The smear may not adhere to the slide

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

purple; purple

Like prokaryotic cells, most eukaryotic cells have an external cell wall

False

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

purple; purple

The concept that living organisms arise from nonliving material is called

Spontaneous generation

The first surgical antiseptic to be used was

Phenol

Negative staining facilitates the visualization of bacterial capsules that are intensely stained by the procedure

False

The endosymbiotic hypothesis is generally accepted as the origin of eukaryotic organelles

True

The Gram-staining procedure is an example of

Differential staining

According to the endosymbiosis hypothesis

A. the first endosymbiont was a fermentative organism

B. the mitochondrion evolved from the same endosymbiont as the hydrogenosome

C. the first endosymbiotic event involved an anaerobic bacterium

D. All of the choices are correct

D. All of the choices are correct

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)

In the Gram-straining procedure, the counterstain is

Safranin

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

pink; pink

BLANK are hollow tube-like structures that hold some archaeal daughter cells together after cell division while BLANK are grappling hook-like structures that appear to attach archaeal cells to surfaces.

Cannulae; Hami

Light rays are refracted (bent) when the cross the interface between materials with different refractive indices.

True

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

Pili

The concept that human and animal diseases are caused by microorganisms is called the

Germ theory

Which of the following is/are true of capsules?

A. They prevent entry of many bacterial viruses

B. They help bacteria escape phagocytosis by host cells

C. They retain water and help prevent desiccation of the bacteria

D. All of the choices are correct

D. All of the choices are correct

The genetic code is expressed differently in bacterial and archaeal cells than in eukarotic cells

False

The major site of cell membrane synthesis is the

endoplasmic reticulum

Confocal microscopes exhibit improved contrast and resolution by

blocking out stray light with an aperture located above the objective lens

What is the most compelling reason why DNA, rather than RNA, evolved to be the storage repository for genetic information in cellular life forms?

DNA molecules are more chemically stable than RNA molecules

Edward Jenner's work in preventing rabies led to the use of the term vaccination to describe a type of procedure used in the prevention of disease.

False

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:
A. sequence of small subunit ribosomal RNA
B. presence or absence of peptidoglycan in cell walls
C. presence of absence of double-stranded circular DNA genome
D. type of membrane lipids

C. presence of absence of double-stranded circular DNA genome

Flexible bacteria with a helical shape are called

spirochetes

External structures that are found in archaea but not bacteria are

hami

The instrument that produces a bright image of the specimen against a dark background is called a BLANK microscope

dark-field

The relationship between specific bacteria and specific diseases was first demonstrated by Koch

True

Although similar in function, the eukaryotic ribosome is generally smaller and more complex than bacterial and archaeal ribosomes

False

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

Each of the following provides evidence in support of the primary role of RNA in the evolution of life EXCEPT A. some RNA molecules are catalytic B. ATP (energy currency of the cell) is a ribonucleotide

C. RNA is less chemically stable than DNA

D. RNA can regulate gene expression

C. RNA is less chemically stable than DNA

The cytoplasmic membrane of bacteria

A. retains the cytoplasm and its contents

B. is the major site of ATP synthesis in aerobes

C. acts as a selectively permeable barrier, allowing some molecules to pass while preventing the movement of others

D. all of the choices are correct

D. all of the choices are correct

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

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.

Old cultures of bacteria that have lost their ability to cause disease are said to be

attenuated

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

microfilaments

Koch's postulates were instrumental in establishing that the intracellular parasite Mycobacterium leprae is the causative organism of leprosy

False

Lysosomes are membrane-bound vesicles that arise from the

Golgi apparatus

The lysosome contains BLANK enzymes

hydrolytic

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

A. Intestinal cell

B. Brain cell

C. Kidney cell

D. Skin cell

E. Phagocytosing white blood cell

E. Phagocytosing white blood cell

Lysosomes function in the destruction and recycling of old organelles

True

The enzymes found in lysosomes were synthesized by ribosomes located on the endoplasmic reticulum

True

Pasteur's Swan Neck Experiment

Disproved spontaneous generation

The abnormal form of the protein is designated

PrPSc

Prions cause BLANK 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

True

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

True

Label the diagram outlining the steps involved in following Koch's postulates

See image

What best describes transcription?

DNA to RNA

What best describes translation?

RNA to Protein

Nucleotides are the building blocks of

both DNA and RNA

A structural gene encodes the information for a specific protein

True

The amino acid sequence of a protein determines its shape and specific function

True

After the initiation step of protein synthesis, transfer RNAs carrying amino acids bind to the ribosome at the

A site

The initiating transfer RNA, carrying formylmethionine, binds to which site?

P site

What type of bond is found connecting amino acids together during protein synthesis?

Peptide bonds

New amino acids (other than the inital f-Met) enter at which site?

AA

At the E site,

transfer RNA is released

After the ribosome moves to the next codon on the mRNA, the growing peptide chain is found in which position?

P

A stop codon codes for an amino acid as well as the signal to stop

False

Select all the differences between cellular DNA and cellular RNA to test your understanding of these nucleic acids.

A. DNA is double-stranded, RNA is single-stranded

B. DNA nucleotides contain deoxyribose whereas RNA nucleotides contain ribose

C. DNA contains the following nitrogenous bases: adenine, cytosine, guanine, and uracil; RNA contains adenine, cytosine, guanine, and thymine

D. There are multiple types of DNA with different functions whereas there is only one type of RNA

A. DNA is double-stranded, RNA is single-stranded

B. DNA nucleotides contain deoxyribose whereas RNA nucleotides contain ribose

Label each part of a generalized amino acid

See picture

Which of these techniques sterilizes on the basis of the size of the microbes to be removed?

A. UV raditation

B. Filtration

C.Bacteriophage therapy

D. Autoclaving

B. Filtration

A mutation that changes the amino acid sequence of the resulting protein by substitution is called a BLANK mutation

missense

Eukaryotic ribosomes differ from bacterial ribosomes in that the eukaryotic ribosomes

are larger in size and require more initiation factors in order to positioned properly on the mRNA

Microorganisms are at their most uniform in terms of chemical and physiological properties during BLANK phase

exponential

DNA in cells can encode thousands of different proteins. Why do cells require mechanisms to regulate expression of the genes that code for these proteins?

Not all proteins are needed at all times, or in equal amounts. Regulating their expression saves energy and time.

Organisms that grow near deep-sea volcanic vents are likely to be

thermophilic

The bacterial initiator tRNA is fMet-tRNAi^Met whereas the eukaryotic initiator tRNA lacks the formyl group on the amino moeity; Met-tRNAi^Met. Archaea, which, like bacteria, lack a nucleus, utilize the same initiator tRNA as bacteria, fMet-tRNAi^Met in the initiation of translation.

False (Archaea use the same initiator tRNA as Eukaryotes)

Which microbial control method best describes the process of pasteurization?

Heat

Nonsense mutation

A mutation that changes a codon encoding an amino acid to a stop codon, resulting in premature termination of polypeptide synthesis

Missense mutation

A mutation that results in changing a codon such that a different amino acid is inserted

Silent mutation

A mutation that changes a codon into a different codon, but both codons specify the same amino acid; this causes no change in the resulting polypeptide

Frameshift mutation

A mutation resulting from an insertion or deletion of bases that causes a change in the reading frame of the mRNA

Genes for antibiotic resistance can be found in antibiotic-producing bacteria as well as in non-antibiotic-producing bacteria

True

Most bacterial and archaeal cells divide by

Binary fission

During replication, the point where separation of the DNA double helix occurs is called the replication fork

True

Arrange the images in their proper order to assess your knowledge of binary fission

1. A young cell at early phase of cycle
2. A parent cell prepares for division by enlarging its cell wall, cell membrane, and overall volume. Chromosome replication begins
3. The septum begins to grow inward as the chromosomes move toward opposite ends of the cell. Other cytoplasmic components are distributed to the two developing cells.
4. The septum is synthesized completely through the cell center, and the cell membrane patches itself so that there are two separate cell chambers
5. Two daughter cells are produced. Some species separate completely as shown here, while others remain attached, forming chains, doublets, or other cellular arrangements.

Which will require a longer time to kill? A. A larger population of microorganisms

B. There is no way to predict which will require a longer kill time

C. Killing will be equally as rapid in a large or small microbial population

D. A smaller population of microorganisms

A. A larger population of microorganisms