Micro

Which of the following are terms associated with Okazaki fragments?

Lagging strand, DNA ligase, and discontinuous

Which DNA strand is synthesized continuously?

Leading strand

The Lake of the Ozarks is a human-made lake, so it collects runoff from coal strip-mining, fertilizers, resort wastewaters, and septic drainages. The average lake temperature is between 10∘∘C and 21∘∘C. Consider the physical requirements for growth and multiplication that would allow fecal coliforms to "blossom" in the Lake of the Ozarks. Which of the following would accurately describe these organisms?

Mesophiles and Facultative halophiles

In which stage is the viral DNA introduced into the cell?

Penetration

Why does the structure of plant and bacterial cells illustrate the reason for having few enveloped viruses that infect these cells?

Plant and bacterial cells contain cell walls that limit the virus from budding out and obtaining the envelope.

Why must primase be used before DNA polymerase when replicating DNA?

Primase provides an RNA primer with a 3' end on which DNA polymerase can act.

According to the animation, which of the following makes mRNA from the information stored in a DNA template?

RNA polymerase

Which of the following groups contains some representatives with genomes that are so small that they may have as few as two genes?

RNA viruses

Which of the following is true about viral infection?

Viruses are very specific in which cells they infect. For a virus to be taken up by a cell, it must find a cell with appropriate receptors on the surface; it cannot be taken up by cells without the appropriate receptors.

What is the function of the connector proteins?

They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.

How are viruses different from cells?

They require a host in order to reproduce.

What is the function of the structural elements of a virus?

To package and protect the viral genome

What are the products of semiconservative replication for a double-stranded DNA molecule?

Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.

Which of the following is NOT a way in which viruses are different from living organisms?

Viruses are obligate parasites and no living organisms are obligate parasites.

Why would using nitrogenous fertilizer near a body of water affect the organisms in the body of water?

When runoff enters the body of water, the nitrogen level significantly increases, which increases the activity of the microorganism there and upsets the balance of the ecosystem

Viral genomes can be

1. DNA or RNA 2. single or double stranded 3. positive or negative sense

Decomposition of organic carbon ultimately results in the formation of __________.

CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

According to the animation, ribosomes move along the mRNA in which direction?

5' to 3'

During elongation, how is the RNA synthesized?

5' to 3'

In which direction does DNA polymerase synthesize DNA for the lagging strand?

5' to 3'

Which of the following events occurs during transcription?

A molecule of RNA is formed based on the sequence of nucleotides in DNA.

What results from the process of translation?

A polypeptide

What is the benefit for a bacteriophage to be a temperate (or lysogenic) virus?

A single infection event can produce millions of new viral particles instead of hundreds of viral particles.

Why is DNA replication essential for a cell?

An organism must copy its DNA to pass genetic information to its offspring.

In which stage does formation of mature viruses occur?

Assembly

How is bacterial translation different from eukaryotic translation?

Bacteria can begin translation before transcription has terminated.

The host DNA is usually degraded during which stage?

Biosynthesis

Which one of the following does not play a role in translation?

DNA

What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands?

DNA is flexible.

Which enzyme joins the gaps between synthesized DNA fragments of the lagging strand?

DNA ligase

Which statement about DNA replication is FALSE?

DNA ligase adds nucleotides to the lagging strand.

The molecule that seals the gaps between the pieces of DNA in the lagging strand is

DNA ligase.

Which of the following build(s) new strands of DNA?

DNA polymerases

List the steps of the central dogma of molecular biology in the correct order.

DNA → RNA → protein

Some viruses, especially animal viruses, have an envelope surrounding their nucleocapsid. This envelope may have viral proteins embedded in it. Why are the viral proteins more readily recognized and targeted by the immune system than the envelope?

Enveloped viruses are often coated with animal cell membrane as they leave the cell. This membrane is a major component of the viral envelope. The viral proteins are more readily recognized by the immune system, as they are more distinct from the materials normally found in and on the cells. However, the envelope can contain several types of viral components as well.

Which of the following events might trigger induction of a temperate bacteriophage?

Exposure to UV light

Which strand will require more RNA primers to complete synthesis?

Lagging strand

Differentiate between persistent and latent animal virus infections.

In a persistent infection, the host cell is continually releasing new viral particles slowly. In a latent infection, there are periods of time where the virus is not replicating and creating new viral particles.

How would one increase the concentration of a particular polypeptide in a cell?

Increase the level of transcription

What is the fate of the prophage during the lysogenic stage?

It is copied every time the host DNA replicates.

Retroviruses become proviruses integrated into the host chromosome soon after infecting the host cell, and can remain there indefinitely. The provirus DNA can then be transcribed and translated by the host cell, making new retroviral RNA genomes, enzymes, and structural proteins. New retroviral virions can then assemble and bud through the host cell membrane continuously over long periods of time. What is one implication of this retroviral life cycle?

It is difficult to completely cure an animal host of the virus, since anti-retroviral drugs will only eliminate circulating virions, not proviruses.

What is the function of the parental DNA in replication?

It serves as the template for DNA replication.

During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA?

T

What nucleotides would DNA polymerase add if it encountered the nucleotide sequence: ATTGC?

TAACG

Given the following DNA sequence (5' ( 3'), what would be the DNA sequence on the complementary strand (3' ( 5') of a double-stranded helix molecule? DNA sequence: AGTCCGA

TCAGGCT

How is penetration different in animal viruses as compared to bacterial viruses?

The entire viral particle can penetrate an animal cell, while only the viral genome can penetrate a bacterial cell.

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?

The host cell dies during the lytic stage.

In addition to physical requirements, bacterial growth and multiplication also entails chemical requirements. Which of the following statements would accurately describe chemical requirements and conditions associated with growth in the Lake of the Ozarks environment?

The lake environment will support the growth of facultative anaerobes. Fecal coliforms will likely contain enzymes to counteract toxic oxygen forms. Fecal coliforms will need to acquire trace elements for growth in the lake environment.

Plaque assays are often used to estimate the number of virions in a sample of a particular volume (the titer). The count is given as plaque-forming units. Which of the following is NOT generally a concern that must be considered in evaluating the results of plaque assays?

The largest problem is that single viruses may create multiple plaques, resulting in overestimates of the number of viruses present.

Which statement about DNA replication is CORRECT?

The leading strand is built continuously, and the lagging strand is built in pieces.

What is the initial target of RNA polymerase?

The promoter

Why is the DNA synthesis of the lagging strand considered discontinuous?

The synthesis is moving in the opposite direction from the replication fork.

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?

The virus would not be able to infect new hosts.

Proofreading of newly-synthesized DNA is important because __________.

a high fidelity in the copying of DNA is necessary for good heredity

Lysogenic viral DNA integrating into the host genome is referred to as

a prophage

When determining the number of virus particles in a suspension, why is the number obtained always less than the actual viral titer?

because all of the virus particles do not infect with 100% efficiency

Bacteria naturally prefer company instead of solitude for growth. Examples of this kind of communal growth pattern can be found everywhere, from surfaces of the teeth and the intestines, to the surface of a slimy rock in the lake, to the thick floc that clogs water pipes. These examples of communal bacterial growth are known by what name?

biofilm

viable methods of release of newly assembled viral particles

budding or lysis of host cell

Increases in atmospheric carbon dioxide concentrations leads to acidification of the oceans as CO2 dissolves in the water and forms carbonic acid. This acidification is predicted to have a major effect on the carbon cycle, as well as the calcium and silica cycles, due to the roles of Ca+ and Si in __________.

building the shells and frustules of microscopic algae and some animals

What component(s) make up the structure of a virion?

capsid and genome

Plasmids function in bacterial cells to __________.

confer to a cell additional genetic traits that are needed only under certain circumstances

Sampling lake water for microscopic organisms is not as easy as it sounds when you want to both count and identify species. In a given water sample, your bacteria of choice can be rare or difficult to culture, particularly given the mixture of bacteria in a biofilm. Which of the following culture media would be best for growing fecal coliforms when they are relatively less abundant than other bacteria in the lake?

enrichment culture medium

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________.

fermentation

Cultures of the Lake of the Ozarks water samples were grown on enrichment media for identification. However, these organisms are present to some degree in all samples. An important question from a clinical perspective is whether or not there is a significant increase in the fecal coliform populations that would put people's health at risk. If you were part of the team investigating this outbreak, how would you best enumerate the fecal coliform threat?

filtration count culture

Human influences on the carbon cycle may cause major upsets in the balance of the ecosystem because __________.

increasing the anthropogenic carbon dioxide released in the atmosphere may significantly decrease the amount of calcium carbonate in the deep ocean

Which of the following does not occur during RNA processing?

mRNA attaches to the small subunit of a ribosome.

Which of the following is a correct statement about mRNA?

mRNA moves from the nucleus to the cytoplasm following RNA processing.

Transcription produces which of the following?

mRNA, tRNA, and rRNA are all produced by transcription.

RNA that has hydrogen bonded to itself forms a

stem loop

Lysozymes and penicillin both disrupt the bacterial cell wall peptidoglycan, leading to cell lysis. However, their mechanisms of action are different, resulting in the fact that __________.

penicillin kills only growing bacterial cells

Bacteria can survive the presence of antibiotics through a variety of mechanisms. Which of the following would NOT be a genetically inherited form of antibiotic resistance?

persistence

Genetic information in the cell is held by information molecules, including all EXCEPT which of the following?

phospholipids

Match the bacterial genetic element with the correct characteristic.

plasmid -- nonessential genes

As nutrients cycle in the biosphere, __________ can participate in every transformation from one chemical form of a nutrient to another.

prokaryotes

Ribosomes contain which of the following?

rRNA

The site of translation is

ribosomes in the cell cytoplasm.

Which statement best describes an operon?

several genes, next to each other in prokaryotic DNA, that are transcribed as a single piece of mRNA

A plasmid differs from the bacterial chromosome in that it is __________.

significantly smaller

A retrovirus has a genome that consists of __________.

ssRNA

The process of synthesizing proteins involves translating one "language," nucleic acid sequences, into another "language," amino acid sequences. The cellular component that does the actual translating from codons to amino acids is the __________.

tRNA

Which of the following is involved in bringing amino acids to the ribosomes?

tRNA

RNA polymerase is guided by the

template strand of DNA.

Antibiotics are produced by bacteria and fungi as a defense mechanism against other organisms. Which of the antibiotic targets listed would be LEAST useful in a clinical setting due to possible toxicity?

the DNA major groove