20 Questions
The bacterium does not burst open to release mature T4 particles.
False
The process of DNA injection into the bacterium can be visualized by cryoelectron microscopy in stained samples.
False
Prokaryotes do not have the capacity to take up nonviral DNA molecules from their surroundings.
False
Horizontal gene transfers occur frequently between different species of eukaryotes.
False
The bacterium bursts open to release immature T4 particles.
False
The DNA injection process can be visualized through light microscopy.
False
Prokaryotes do not have the ability to capture genetic information from their surroundings.
False
The heads of new T4 particles are found outside the bacterium.
False
Vibrio cholerae is a bacterium that causes cholera.
True
Escherichia coli is a pathogenic bacterium that can cause disease in humans.
False
Phototrophic species can generate oxygen as a by-product of harvesting light energy.
True
Lithotrophic species obtain their energy from consuming organic compounds.
False
Vibrio cholerae has a single flagellum at one end.
True
Escherichia coli has no flagella.
False
Viruses can infect cells of the same species only.
False
The infected cell is always killed by the massive proliferation of virus particles inside it.
False
Viruses can accidentally pick up fragments of DNA from the genome of one host cell and ferry them into another cell.
True
Horizontal transfers of genes between eukaryotic cells of different species are very common.
False
Viruses always insert their DNA into the cell's regular genome.
False
Massive transfers of genes from bacterial to eukaryotic genomes have not occurred in the evolution of mitochondria and chloroplasts.
False
Study Notes
Bacteriophages
- The large dark objects inside the bacterium are the heads of new T4 particles in the course of assembly
- The bacterium will burst open to release mature T4 particles
- The process of DNA injection into the bacterium can be visualized by cryoelectron microscopy
- Attachment of the virus to the bacterium initiates DNA injection
- The virus head empties its DNA into the bacterium, which then bursts open to release the mature virus particles
Gene Transfer
- Horizontal gene transfers occur frequently between different species of prokaryotes
- Prokaryotes can take up nonviral DNA molecules from their surroundings and capture the genetic information
- Viruses can replicate in one cell, emerge, and infect another cell, potentially of a different species
- Viral DNA can persist in the host cell for many generations as a separate intracellular fragment of DNA (plasmid) or a sequence inserted into the cell's genome
- Horizontal transfers of genes between eukaryotic cells of different species are very rare
Prokaryotes
- Phototrophic species harvest light energy in various ways, some generating oxygen as a by-product
- Lithotrophic species feed on inorganic nutrients, getting their carbon from CO2 and relying on chemicals like H2S, H2, Fe2+, or elemental sulfur for energy
- Bacteria have a simple internal organization, with a flagellum that rotates as a propeller to drive the cell forward
- Examples of bacteria include Vibrio cholerae and Escherichia coli (E. coli), which have flagella distributed over their surface
This quiz covers the process of viral replication and DNA injection into bacteria, including the assembly of new T4 particles and their release from the bacterial cell.
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