Term
| What is an example of a prokaryote with cells much smaller and more simply organized than those of eukaryotes? |
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Definition
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Term
| What are used frequently by researchers in studies that reveal broad biological principles? |
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Definition
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Term
| What are the infectious particles consisting of nucleic acid enclosed in a protein coat and, in some cases, a membranous envelope? |
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Definition
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Term
| What may consist ofdouble-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA? |
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Definition
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Term
| What is the protein shell enclosing the viral genome called? |
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Definition
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Term
| What are the three shapes a capsid can take? |
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Definition
| Rod-shaped, polyhedral, or more complex in shape. |
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Term
| What are the large numbers of protein subunits that capsids are built from called? |
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Definition
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Term
| What are derived from the membrane of the host cell and contain host cell phospholipids and membrane proteins? |
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Definition
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Term
| What are the viruses with the most complex capsids called? |
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Definition
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Term
| What type of virus has an elongated icosahedral head enclosing their DNA and a protein tail piece with fibers that are used to attach to a bacterium? |
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Definition
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Term
| What are viruses that can reproduce only within a host cell? |
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Definition
| Obligate intercellular parasites. |
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Term
| What is the limited range of host cells that each type of virus can infect? |
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Definition
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Term
| How do viruses identify their host cells? |
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Definition
| Lock-and-key fit between proteins on the outside of the viruse and specific receptor molecules on the surface of cells. |
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Term
| When does a viral infection begin? |
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Definition
| When the genome of a virus makes its way into a host cell. |
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Term
| What occurs once a viral genome has entered a cell? |
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Definition
| It can commandeer its host and reprogram the cell to copy the viral nucleic acid and manufacture viral proteins. |
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Term
| What is the difference between the way DNA viruses replicate and the way RNA viruses replicate? |
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Definition
| DNA viruses use the DNA polymerases of the host cell to synthesize new genomes while RNA viruses use special virus-encoded polymerases that can use RNA as a template. |
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Term
| What are the best understood of all viruses? |
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Definition
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Term
| What is the phage reproductive cycle that culminates in death of the host cell known as? |
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Definition
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Term
| What does the mean when a cell "lyses?" |
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Definition
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Term
| What is a phage that reproduces only by a lytic cycle called? |
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Definition
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Term
| What are the three ways bacteria defend against extinction by viruses? |
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Definition
| Natural selection, DNA is often recognized as foreign and cut up by restriction enzymes, and because many phages coexist with bacteria in a lysogenic cycle. |
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Term
| What is another name for restriction enzymes? |
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Definition
| Restriction endonucleases. |
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Term
| What replicates the phage genome without destroying the host? |
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Definition
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Term
| What are phages capable of using both the lytic cycle and the lysogenic cycle? |
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Definition
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Term
| What is viral DNA that has been incorporated into the bacterial chromosome by genetic recombination known as? |
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Definition
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Term
| How does a prophage gene prevent transcription of most of the other prophage genes? |
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Definition
| It codes for a protein that prevents transcription of most of the other prophage genes. |
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Term
| What occurs when the viral genome exits the bacterial chromosome and initiates a lytic cycle? |
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Definition
| Active phages will lyse their host cells. |
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Term
| What triggers the switchover from the lysogenic to the lytic mode? |
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Definition
| Environmental signal such as radiation or the presence of certain chemicals. |
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Term
| Why is it important that prophages have genes that may be expressed during lysogenic cycles? |
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Definition
| They may alter the host's phenotype. This phenomenon can have important medical significance. |
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Term
| What is the basis for the common classification of viruses? |
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Definition
| Nature of the genome. DNA or RNA? Double-stranded or single-stranded? Presence or absence of a membranous envelope derived from host cell membrane? |
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Term
| What do nearly all animal viruses with RNA genomes have? |
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Definition
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Term
| What are the three classes of single-stranded RNA viruses? |
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Definition
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Term
| What is the acronym for Double-stranded DNA viruses? |
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Definition
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Term
| What is the acronym for single-stranded DNA viruses? |
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Definition
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Term
| What is the acronym for double-stranded RNA viruses? |
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Definition
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|
Term
| What is the acronym for single-stranded RNA viruses? |
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Definition
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Term
| What class of animal viruses serves as mRNA? |
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Definition
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Term
| What class of animal viruses are a template for mRNA synthesis? |
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Definition
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Term
| What class of animal virus is the template for DNA synthesis? |
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Definition
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Term
| What does an animal virus equipped with an outer membrane or viral envelope use it for? |
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Definition
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Term
| What protrudes from the outer surface of the viral envelope? |
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Definition
|
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Term
| What do viral glycoproteins do? |
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Definition
| Bind to specific receptor molecules on the surface of a host cell. |
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Term
| Where are viral glycoproteins for new viral envelopes made? |
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Definition
| By cellular enzymes in the endoplasmic reticulum (ER) of the host cell. |
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Term
| What kind of viruses are some phages and most plant viruses? |
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Definition
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Term
| Where is the broadest variety of RNA genomes found? |
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Definition
| Among the viruses that infect animals. |
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Term
| What are the viruses with the most complicated reproductive cycles? |
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Definition
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Term
| What enzyme are retroviruses equipped with? |
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Definition
|
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Term
| What does reverse transcriptase do? |
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Definition
| Transcribes an RNA template into DNA, the opposite of the usual direction. |
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Term
| What is integrated viral DNA called? |
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Definition
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Term
| What is one of the aspects that the amount of damage a virus causes depends on? |
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Definition
| The ability of the infected tissues to regenerate by cell division. |
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Term
| What are harmless variants or derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the actual pathogen? |
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Definition
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Term
| What are viruses that appear suddenly or that suddenly come to the attention of medical scientists referred to as? |
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Definition
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Term
| What is an often fatal syndrome characterized by fever, vomiting, massive bleeding, and circulatory system collapse? |
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Definition
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Term
| What type of viruses tend to have an unusually high rate of mutation because of errors in replicating their genomes are not corrected by proofreading? |
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Definition
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Term
| Scientists estimate that what percentage of new human viruses originate in other animals?: |
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Definition
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Term
| What are the two major routes that plant viral diseases are spread by? |
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Definition
| Horizontal transmission and vertical transmission. |
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Term
| What it is it called when a plant is infected from an external source of the virus? |
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Definition
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Term
| What is it called when a plant inherits a viral infection from a parent? |
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Definition
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Term
| After a virus enters a plant cell and begins reproducing, how can viral components spread throughout the plant? |
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Definition
| By passing through plasmodesmata. |
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Term
| What are circular RNA molecules, only several hundred nucleotides long, that infect plants? |
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Definition
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Term
| What do not encode proteins but can replicate in host plant cells, apparently using cellular enzymes? |
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Definition
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Term
| What are infectious proteins which appear to cause a number of degenerative brain diseases in various animal species? |
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Definition
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Term
| What are two characteristics of prions that are especially alarming? |
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Definition
| Incubation period before symptoms appear is around ten years. Virtually indestructible. |
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Term
| What is the laboratory rat of molecular biology? |
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Definition
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Term
| What is a double-stranded, circular DNA molecule that is associated with a small amount of protein referred to as? |
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Definition
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Term
| What is the dense region of DNA in a prokaryote not bounded by membrane? |
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Definition
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Term
| How does bacteria reproduce? |
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Definition
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Term
| What are the three processes that bring together bacterial DNA from different individuals? |
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Definition
| Transformation, transduction, and conjugation. |
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Term
| What is the alteration of a bacterial cell's genotype and phenotype by the uptake of naked, foreign DNA from the surrounding environment? |
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Definition
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Term
| In what process do phages carry bacterial genes from one host cell to another as a result of aberrations in the phage reproductive cycle? |
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Definition
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Term
| What is a process by which bacterial genes are randomly transferred from one bacterial cell to another? |
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Definition
| Generalized transduction. |
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Term
| What is sometimes referred to as bacterial "sex?" |
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Definition
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Term
| What is the direct transfer of genetic material between two bacterial cells that are temporarily joined? |
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Definition
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Term
| What are the appendages called that are used in bacterial conjugation? |
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Definition
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Term
| What is formed between two cells involved in conjugation that provides an avenue for DNA transfer? |
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Definition
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Term
| What is a DNA segment that confers the ability to form pili for conjugation and associated functions? |
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Definition
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Term
| What does the "F" in F factor refer to? |
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Definition
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Term
| What are the two forms an F factor can exist as? |
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Definition
| Segment of DNA within the bacterial chromosome or as a plasmid. |
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Term
| What is a small, circular self-replicating DNA molecule separate from the bacterial chromosome? |
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Definition
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Term
| What is a genetic element that can replicate either as part of the bacterial chromosome or independently of it called? |
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Definition
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Term
| What is the plasmid form of the F factor referred to as? |
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Definition
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Term
| What is a cell with the F factor built into its chromosome called? |
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Definition
| Hfr cell (High frequency of recombination). |
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Term
| What is a bacterial plasmid carrying genes that confer resistance to certain antibiotics? |
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Definition
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Term
| What is a segment of DNA that can move within the genome of a cell by means of a DNA or RNA intermediate? |
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Definition
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Term
| What is it called when the transposable element moves from one site in a cell's DNA to another site-target site- by a type of recombination process? |
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Definition
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Term
| In a bacterial cell, how can a transposable element move within the chromosome? |
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Definition
| From a plasmid to the chromosome (or vice versa), or from one plasmid to another. |
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|
Term
| What is another name for transposable elements? |
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Definition
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|
Term
| What are the simplest transposable elements called? |
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Definition
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|
Term
| Where do insertion sequences only exist? |
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Definition
|
|
Term
| What is an enzyme that catalyzes movement of the insertion sequence from one site to another within the genome? |
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Definition
|
|
Term
| What are base sequences that bracket the transposase gene called? |
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Definition
| Inverted repeats. The base sequence at one end of the insertion sequence is repeated upside down and backward (inverted) at the other end. |
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|
Term
| What is the purpose of inverted repeats? |
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Definition
| They allow transposase to recognize them as the boundaries of the insertion sequence. |
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|
Term
| What are transposable elements longer and more complex than insertion sequences called? |
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Definition
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|
Term
| Why are transposons beneficial to bacteria? |
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Definition
| They may help bacteria adapt to new environments. |
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Term
| What are the two levels that metabolic control in bacteria occurs? |
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Definition
| Cells can adjust the activity of enzymes already present. Cells can adjust the amount being made of certain enzymes. |
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Term
| In prokaryotic DNA, what is a sequence of nucleotides near the start of an operon to which an active repressor can attach? |
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Definition
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|
Term
| What prevents RNA polymerase from attaching to the promoter and transcribing the genes of the operon? |
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Definition
| The binding of the repressor. |
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|
Term
| What is a unit of genetic function common in bacteria and phages, consisting of coordinately regulated clusters of genes with related functions? |
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Definition
|
|
Term
| What "switches off" the operon? |
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Definition
|
|
Term
|
Definition
| A protein that switches off the operon. |
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|
Term
| When are regulatory genes expressed? |
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Definition
| Continuously (although at a low rate). |
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|
Term
| What is a small molecule that cooperates with a repressor protein to switch an operon off? |
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Definition
|
|
Term
| What is an operon that is usually on but can be inhibited when a specific small molecule binds allosterically to a regulatory protein? |
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Definition
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|
Term
| What is an operon that is usually off but can be stimulated when a specific small molecule interacts with a regulatory protein? |
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Definition
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|
Term
| What is a specific small molecule that inactivates the repressor in an operon? |
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Definition
|
|
Term
| What are enzymes whose synthesis is induced by a chemical signal? |
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Definition
|
|
Term
| Where do repressible enzymes generally function? |
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Definition
| Anabolic pathways which synthesize essential end products from raw materials. |
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|
Term
| Where do inducible enzymes generally function? |
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Definition
| Catabolic pathways which break down a nutrient to simpler molecules. |
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|
Term
| When does cAMP accumulate? |
|
Definition
|
|
Term
| What is catabolite activator protein (CAP)? |
|
Definition
| An activator of transcription. |
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|
Term
| What happens when cAMP binds to CAP? |
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Definition
| CAP assumes its active shape and can bind to a specific site. |
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