Microbio exam 3

transformation

Increasing genetic variability by the uptake of DNA from the environment

integrases

appropriate target(s) for antiviral drugs

What is unique about transduction compared to normal bacteriophage infection?

Transduction transfers DNA from the chromosome of one cell to another.

Lysogeny

confers resistance to infection by viruses of the same type.

Viral replication

independent of the host cell's DNA but dependent on the host cell's enzymes and metabolism

A silent mutation is so named because

it has no effect on the overall amino acid sequence

Double stranded DNA Virus

replicate using DNA polymerase either on its own or from a host replicate, translates, and transcribes similar to prokaryotic or eukaryotic cells

ssingle stranded DNA virus

replication involes a complimentary DN strand replicate using DNA polymerase either on its own or from a host

divergent evolution

when a single species splits into two or more species due to evolutionary change.

The term "phage" is generally reserved for the viruses that infect

Bacteria

Viruses infecting ________ are typically the easiest to grow in the laboratory.

prokaryotes

axenic

pure culture

Which type of transposon would contain a gene for transposase

simple and complex transposons

point mutation

substitution, deletion, or addition of one base-pair

convergent evolution

when organisms share a trait that was NOT inherited from a common ancestor

A new chemotherapeutic agent is developed that alters the structure of all thymines in DNA. These thymines are then misread during the production of mRNA. Which of the following could NOT result from this type of mutation

frameshift mutation

Second Stage of Bacteriophage replication

penetration of viral nucleic acid

How do complex transposons differ from simple transposons

Complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposase gene essential for the tranposon itself.

Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate?

Conjugation does not result in the formation of new offspring.

conjugation

E. coli is the model for bacterial conjugation. After conjugation, each cell involved has a copy of the shared DNA.

How is generalized transduction different from specialized transduction?

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

Reverse transcriptase is

RNA-dependent DNA polymerase.

What are the minimal components needed for a virion?

capsid and genome

double stranded RNA virus

carry their own nucleic acid polymerase to replicate viral genome

fifth stage of bacteriophage replication

cell lysis and release of new virons

Competent cells

cells that can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.

Transduction

genetic exchange using a bacteriophage

RNA viruses

genomes that are so small that they may have as few as two genes

When a transducing phage interacts with a new host cell,

the DNA from the previous host can recombine with the new host chromosome.

What must occur for bacterial conjugation to take place?

the cells must touch

what is transferred during bacterial conjugation

A bacterial plasmid

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.

Mutations

changes in the DNA sequence that are inherited through vertical gene transfer

Horizontal gene transfer

complicates the construction of phylogenetic trees and the interpretation of specific traits in relation to evolution.

retrovirus

contain and RNA-dependent DNA polymerase called reverse transcriptase to generate a new DNA intermediate

A transducing phage

contains fragments of the host chromosome instead of the viral genome.

single stranded RNA virus

genome configurations are either (+) or (-) sense carry their own nucleic acid polymerase to replicate viral genome

What is the benefit, for a virus, to be a temperate or lysogenic virus?

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

When determining the number of bacterial 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.

First step of bacteriophage replication

Attachment

When solutions of host cells and infectious virions are mixed and spread on an agar plate, ________ form where viruses lyse the host cells.

plaques

Third stage of Bacteriophage replication

synthesis of viral nucleic acids and proteins

viruses are different from living things because:

1.) Viruses are acellular and all living things are made up of cells 2.)Viruses depend on their host to synthesize the essential components of new viruses (e.g., genetic material and proteins), while living organisms are capable of synthesizing these components even if they require a host for food, shelter, or other necessities 3.)Viruses have DNA or RNA, not both

evolution

A change in allele frequencies in a set of organisms over time

Viruses rely on the host cell machinery to make new viruses, but they sometimes provide their own enzymes (such as reverse transcriptase, which is an RNA-dependent DNA polymerase). Which of the following types of enzymes would a virus need to provide in order to replicate within a cell? In other words, which of these enzymes would not normally be found in a cell unless a virus provided it?

RNA replicases (RNA-dependent RNA polymerases) for RNA viruses

Some viruses have plus sense RNA genomes. Which of the following could describe one of those viruses?

a virus that contains RNA with the same nucleotide sequence as the functional mRNA that its host cell will translate to produce viral products

viral particles

are metabolically inert

fourth stage of bacteriophage replication

assembly and packaging of new viruses

DNA ligase

attaches the target gene to a desired location

viruses

many contain their own nucleic acid polymerases cannot replicate on their own smaller than Bacteria and Archaea as old as Bacteria and Archaea genetic information of a virus can be in the form of RNA or DNA. do not belong to any of the three domains: Bacteria, Archaea, and Eukarya

deletions

may increase fitness of a microorganism by eliminating unneeded genes.