MCB 3020 Exam 3 Bacusmo

To carry out Sanger sequencing a mixture is needed containing _________.

single-stranded DNA, DNA polymerase, complementary DNA primer, and four deoxyribonucleotides A,T,C,G

In DNA sequencing. When a dideoxyribonucleotide is added to the daughter strand, replication of the strand ________.

stops

To sequence DNA by the Sanger method, the DNA must first be made in single-stranded form.

DNA sequencing is a technique for determining the complete sequence of bases (i.e., As, Ts, Gs, and Cs) for a particular piece of DNA. Sanger sequencing is the most popular method for DNA sequencing. T/F

True

In the Sanger method, examining the electrophoresis gel and reading from bottom to top, one base at a time, gives the sequence of DNA. T/F

True

Arrange the following events in the proper sequence for gene cloning.

1 = Incorporate gene into bacterial plasmid.

2 = Isolate DNA from organism containing desired gene.

3 = Incorporate cloned gene into bacterial cells.

4 = Fragment DNA with restriction enzyme.

2, 4, 1, 3

The function of the enzyme ligase is to ________.

form covalent bonds between cloned gene and plasmid

"Sticky ends" are ________.

single-stranded DNA sequences that are generated by staggered cuts

Restriction enzymes cut DNA at random sites. T/F

False

Which of the following is not a characteristic of lipid A?

Neurotoxicity

All of the following are components of the mammalian host immune system EXCEPT ________.

leukocytes

phagocytes

antigens

antibodies

antigens

Which of the following is considered to be a biological defense mechanism?

Normal microbiota

Macrophages are phagocytic cells. T/F

True

Which of the following features of a pathogen is not considered to be a virulence factor when establishing infection within a host?

Pigment production

Generally, exotoxins tend to be more heat stable than endotoxins. T/F

False

The lungs are protected from microorganisms by ________.

phagocytic action of alveolar macrophages

All of the choices are correct.

lysozyme in mucus

the mucociliary blanket

All of the choices are correct.

One example of infectious disease transmission by a fomite is _______.

a child developing a cold after playing with a toy that harbored rhinovirus

In a lichen, the fungal partner _________.

All of the choices are correct.

provides a substratum within which the alga grows

protects the alga from excess light intensities

provides water and minerals to the alga

All of the choices are correct.

Blood cell development occurs in the bone marrow of mammals during the process of ________.

hematopoesis

Bacteria within biofilms exchange _________.

nutrients

All of the choices are correct.

quorum-sensing molecules

plasmids

All of the choices are correct.

Methanogens are always engaged in relationships with other microbes because methane production requires _________.

interspecies hydrogen transfer

Cervical mucus has antibacterial activity. T/F

True

The endosymbionts of ruminant animals are useful to their hosts in which of the following ways?

They produce most of the vitamins needed by the ruminant.

They convert glucose to organic acids.

All of the choices are correct.

They digest the cellulose of plant cell walls.

All of the choices are correct.

Why is innate host resistance a type of nonspecific immune response?

Innate resistance is nonspecific because any foreign material, microorganisms, or antigens encountered by the host are targeted.

Which of the following is NOT a virulence factor encoded by a pathogenicity island?

Lysozyme

________ is a predator that bores a hole through the outer membrane of its Gram-negative bacterial prey and then reproduces in the periplasm.

Bdellovibrio

When Nitrobacter utilizes nitrite produced from ammonia by Nitrosomonas to obtain energy by converting the nitrite to nitrate, the relationship between the two organisms is _________.

commensal

An inanimate object that may be contaminated with a pathogen is called a ________.

fomite

rRNA signature sequences can be used to place microorganisms in the correct domain. T/F

True

Which of the following is not part of the lichen association?

Brown algae

The toxic component of lipopolysaccharide is called ________.

lipid A

Lactobacillus contributes to the antimicrobial defenses for the adult female reproductive tract by making lactic acid to lower the pH. T/F

True

Movement of charged molecules in an electrical field, which is used to separate nucleic acid fragments for recombinant DNA work, is called _________.

electrophoresis

Which of the following types of immunity primarily relies on interactions between antigens and antibodies?

Adaptive immunity

In the rumen, food is quickly attacked by cellulase _________.

enzymes produced by microbes

Biofilm formation by Pseudomonas bacteria on the surface of a natural loofa sponge kept in the shower is an example of which type of relationship?

Commensalism

Fever response can be triggered by an endogenous pyrogen called interleukin-1. T/F

True

The mucociliary blanket is found in the digestive system of mammals. T/F

False

The rickettsial parasite Wolbachia pipientis can _________.

sometimes alter the sex of an infected wasp

In which of the following situations did disease develop due to vertical transmission of the pathogen?

A fetus develops listeriosis after unpasteurized cheese infected with Listeria bacteria is consumed by the mother during pregnancy

The reason coral reefs are among the most productive and successful ecosystems is due to _________.

the coral-dinoflagellate mutualistic relationship

When a pathogen is transferred from a water source to an animal before being transferred to a human, the animal is called a(n) ________ agent.

intermediate

Substances that are recognized as foreign and provoke immune responses are called ________.

antigens

The final outcome of most host-pathogen relationships depends on _________.

All of the choices are correct.

the virulence of the organism

the host's defenses

the number of organisms present in or on the host

All of the choices are correct.

The relationship between Trichonympha protozoa and its termite host, and Xenorhabdus bacteria and its nematode host, are both obligatory relationships. T/F

False

In mutualism _________.

the partners will not survive separately in many cases

the mutualist is dependent on the host

All of the choices are correct.

a reciprocal benefit accrues to both partners

All of the choices are correct.

The lower genitourinary tract is usually free of microorganisms. T/F

False

Before bacteria can establish an infection, they must be able to overcome resident microorganisms in direct competition for space and nutrients. T/F

True

A DNA molecule used to carry a foreign gene into a host organism is called a _________.

vector

People with type AB blood have _________.

both type A and type B antigens on their red blood cells

When type B blood is given to a person with type A blood ________.

B antigen from the donor reacts with anti-B antibody in the recipient

A person with type AB blood may receive ________.

types A, B, AB, and O blood

People with type O blood can be universal donors because their red blood cells do not contain either A antigen or B antigen on their surface. T/F

True

A person with type O blood may receive blood from a person with type B blood. T/F

False

The primer used in Sanger sequencing ______

has a nucleotide sequence complementary to the 3’ end of the region to be copied

PCR requires all of the following except

DNA ligase

If you start with one double-stranded DNA molecule and you perform SIX cycles of PCR, how many double-stranded copies of the DNA will you have?

64

The most likely source of the Taq polymerase used in PCR is a bacterium that lives in ______.

Hot vents

T/F. PCR can be used to amplify DNA from any source.

True

T/F. During the PCR, the hydrogen bonds of the double-stranded DNA molecules are broken by the enzyme helicase.

False

Genomics is the study of

-the molecular organization of genomes

-the gene products that genomes encode

-the information content of genomes

All of the above

Study of similarities between nucleotide and amino acid sequences among organisms to infer gene function and evolution is called

Comparative genomics

The proteome

Is the entire collection of proteins that an organism can produce

When observing a microbe in which one gene has been deleted, you often find that the product of the missing gene

Broadly affects gene expression and cellular physiology

When two or more genes from the same genome have nucleotide sequences so alike that they most probably arose from gene duplication those genes are called _______.

Paralogs

T/F. Microorganisms do not generally reproduce sexually; therefore, species are usually defined by phenotypic and genotypic similarities.

True

The binomial system of nomenclature assigns each organism a scientific name consisting of

Genus and species

T/F. Molecular methods are so important to the understanding of microbial evolution and taxonomy because they provide the most robust analysis of microbial evolution.

True

The science dealing with classification is called ______.

Taxonomy

T/F. If Microbe A and Microbe B have whole genome similarity of 68%, as determined by DNA-DNA hybridization, they should be considered the same species.

False

T/F. Conjugation is useful for determining relatedness between bacteria at the species level because it never occurs between organisms of different genera.

False

While inspecting the genome sequence of your newly discovered organism, you note that while the genome overall is 50% G + C, there is a cluster of genes comprising about 20,000 bp that is 64% G + C. The best explanation for this is

the 20,000 bp segment is a recent acquisition via horizontal gene transfer.

Which of the following is an example of the use of the binomial system devised by Linnaeus?

Escherichia coli

T/F. Transformation is not useful in determining relatedness between two organisms because it frequently crosses genera.

False

Which of the following facts support the endosymbiotic hypothesis? Select all that apply.

- Mitochondria and chloroplasts have a single circular chromosome.

- Mitochondria and chloroplasts have 70S ribosomes.

Patients who take antibiotics sometimes experience overgrowth of the fungus Candida albicans in their mouths and throats (a condition called thrush). C. albicans is considered part of the normal flora of the gastrointestinal tract but its population is typically limited by the presence of other microorganisms. Based on this evidence, which of the following types of symbiotic relationship do you think occurs between members of the normal flora and C. albicans?

Competition

Several cases of an emerging infectious disease are reported in workers at a research station that borders a tropical rainforest region. The pathogen is identified as a species of bacteria carried by nematodes that infect mosquitos, and disease transmission occurs in a human host following a mosquito bite. Which organisms should be targeted in the treatment of infected patients?

Nematode and bacteria

The chytrid fungus Batrachochytrium dendrobatidis is colonizing frogs across the globe causing massive mortality and even pushing some amphibian species to the brink of extinction. The Batrachochytrium dendrobatidis-frog relationship can be considered which of the following?

Parasitic

Because you have always been fascinated by spiders and bacteria, you decide to study the microbiome of a species of spider that is locally abundant. You are able to cultivate many bacteria from the spiders gut in the lab, and the spiders do not appear to be negatively affected by treatment with antibiotics that you know will inhibit the growth of these bacteria. Based on this evidence, which of the following types of symbiotic relationships do you suspect might be occurring between the spider and the bacteria?

Commensalistic

You have isolated a soil protozoan, which you are now trying to grow in pure culture. You have tried many different types of media but find you can only grow the protozoan if bacteria are also present in the medium. You note that the bacterial population declines as the protozoan population increases. Based on this evidence, which of the following types of symbiotic relationships do you suspect might be occurring between the protozoan and the bacteria?

Predatation

When Alexander Fleming discovered what was to become penicillin, he noticed that wherever mold was growing on plates of Staphylococus sp., there was a zone of inhibition of bacterial growth around the fungi. What type of symbiotic relationship does this describe?

Ammensalistic

Microbes that normally colonize the mouth must be resistant to

mechanical removal through adhesion

The relationship between the bacterium Xenorhabdus nematophila and its nematode host, Steinernema carpocapsae, is classified as cooperation because both organisms benefit and

X. nematophila and S. carpocapsae can be grown separately

Due to the very acidic environment of the gastric contents, the stomach ______.

Contain few viable bacteria per milliliter

The inhalation of cigarette smoke and similar pollutants has a gradual effect on cilia lining the respiratory tract, first causing the beating to slow and eventually stop. How does this change in cilia most directly impact the resistance mechanisms of the host?

Innate host immunity due to mechanical barrier protection would be lost

Which is a primary reason that females are at greater risk of a urinary tract infection than are males?

The urethra is shorter in women, therefore bacteria are closer in proximity to the bladder.

Which of the following is not normally present in the acidic gastric juice

acetic acid

In which of the following areas of the human body do secretions play the greatest role in preventing microbial colonization?

Stomach

The lungs are protected from microorganisms by _________

-Mucociliary blanket

-Lysozyme in mucus

-Phagocytic action in alveolar macrophages

All of the above

Tears protect the eyes by

flushing and lysozyme

Which of the following is a physical barrier in the nonspecific defense of a mammalian host?

Mucous membranes

Lysozyme is an enzyme that lyses _________.

bacteria

T/F. The skin surface is a very favorable environment for colonization by most microorganisms.

False

The human microbiome _______

evolves with humans over time

On which of the following surfaces can biofilms form?

Biotic or abiotic surface

Initial attachment of microorganisms often involves ______.

flagella and is reversible

Which of the following gradients can form in a biofilm?

Oxygen, nutrient, and/or pH gradient

T/F. Colonization specifically refers to the multiplication of a pathogen on or within a host, and includes the resulting tissue invasion and damage.

False

Why are pathogens that are transmitted person-to-person often less virulent than those transmitted by arthropod vectors?

Person-to-person transmission requires the infected host to remain alive long enough to transmit the organism to another susceptible host.

This type of pathogen cannot grow outside a host cell

Obligate intracellular pathogen

Pathogens produce virulence factors primarily to ______.

outcompete host cells for resources