Chapter 10: Problem 273
A gal \(^{+} /\) gal \(^{-}\) cell is produced by an abortive transduction. Will it grow in a medium in which galactose is the sole carbon source?
Short Answer
Expert verified
A gal+/gal- cell produced by an abortive transduction will not grow in a medium containing galactose as the sole carbon source, as the cell has a non-functional galactose metabolism due to the abortive transduction event.
Step by step solution
01
Understanding abortive transduction
Abortive transduction is the process by which a bacterial cell takes up a piece of DNA from a bacteriophage but is unable to integrate it into its genome. As a result, the DNA is present in the cell, but not functional, and the cell does not inherit the genetic traits carried by the transduced DNA.
02
Understanding gal+ and gal- notations
The gal+ notation represents a bacterial cell strain that is capable of metabolizing galactose, while the gal- notation refers to a cell strain that is unable to metabolize galactose. The formation of a gal+/gal- cell indicates that one part of the cell is capable of metabolizing galactose, and the other is not.
03
Analyzing the growth of a gal+/gal- cell in a galactose medium
Since the bacterial cell is a result of abortive transduction, the piece of DNA responsible for galactose metabolism is most likely present in the cell but not integrated into its genome, rendering it non-functional. This means that, even though the cell is denoted by gal+/gal-, it may not function as a typical gal+ cell.
04
Evaluating the cell's ability to grow in the given medium
A cell must metabolize its carbon source to generate energy and perform biosynthesis for growth. Since galactose is the sole carbon source in the medium, a cell that cannot metabolize galactose will not be able to grow in this environment. As the abortive transduction makes the galactose metabolism non-functional (even though the cell is denoted as gal+/gal-), the cell will not be able to grow in the medium containing galactose as the sole carbon source.
05
Conclusion
A gal+/gal- cell produced by an abortive transduction will not grow in a medium containing galactose as the sole carbon source, as the cell has a non-functional galactose metabolism due to the abortive transduction event.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Bacterial Genetics
Bacterial genetics is the study of how genetic information is transferred, inherited, and expressed within bacterial organisms. It is an essential field that lends insight into fundamental processes such as recombination, mutation, and gene expression. One classical phenomenon explored in bacterial genetics is transduction, a process of horizontal gene transfer facilitated by bacteriophages. Bacteriophages are viruses that infect bacteria and can accidentally package bacterial DNA, transferring it between bacteria.
In particular, abortive transduction is an intriguing concept in bacterial genetics. This occurs when bacterial DNA, delivered by a phage, remains present within a recipient bacterial cell but does not integrate into the bacterial genome. As a consequence, the foreign DNA is typically non-functional because it fails to replicate or express properly within the host cell. This mechanism highlights limitations in gene transfer, since traits believed to be conferred by transferred genes are not expressed in the bacterium permanently. Understanding these mechanisms is crucial for grasping how bacterial populations adapt or fail to adapt to new environments.
In particular, abortive transduction is an intriguing concept in bacterial genetics. This occurs when bacterial DNA, delivered by a phage, remains present within a recipient bacterial cell but does not integrate into the bacterial genome. As a consequence, the foreign DNA is typically non-functional because it fails to replicate or express properly within the host cell. This mechanism highlights limitations in gene transfer, since traits believed to be conferred by transferred genes are not expressed in the bacterium permanently. Understanding these mechanisms is crucial for grasping how bacterial populations adapt or fail to adapt to new environments.
Galactose Metabolism
Galactose metabolism is a vital biological process wherein bacteria convert galactose into usable forms of energy and metabolic intermediates. Bacteria that are labeled as 'gal+' have the genetic capability to metabolize galactose efficiently by utilizing enzymes encoded by their gal operon. These enzymes break down galactose into glucose-1-phosphate, which is then funneled into the common pathways of energy metabolism.
Conversely, 'gal-' bacteria do not possess the functional enzymes necessary to process galactose. When a bacterium is marked as gal-/gal+, it implies a mixed genotype, often resulting from genetic exchange, like transduction. However, without successful integration of necessary genes into the host genome, as seen in abortive transduction, the bacterial cell may not express the required enzymes. Hence, despite the presence of gal+/gal- notation, the organism may struggle or fail to utilize galactose as a carbon source effectively during metabolic processes.
Conversely, 'gal-' bacteria do not possess the functional enzymes necessary to process galactose. When a bacterium is marked as gal-/gal+, it implies a mixed genotype, often resulting from genetic exchange, like transduction. However, without successful integration of necessary genes into the host genome, as seen in abortive transduction, the bacterial cell may not express the required enzymes. Hence, despite the presence of gal+/gal- notation, the organism may struggle or fail to utilize galactose as a carbon source effectively during metabolic processes.
DNA Integration
DNA integration is the process by which foreign DNA is incorporated into an organism's genome, becoming a permanent and functional part of the genetic material. Successful integration allows bacteria to acquire and benefit from new genes, potentially increasing their adaptability and survival in varied environments.
For foreign DNA to be integrated, it typically undergoes recombination with the bacterium's chromosomal DNA. This process is often governed by specific enzymes that facilitate pairing and exchanging of genetic material. Without integration, as seen in abortive transduction, the DNA simply exists within the cell but cannot alter the host's traits or functions significantly. This can pose a limitation in harnessing new traits or abilities like galactose metabolism.
Thus, understanding the factors influencing DNA integration is vital for exploiting genetic engineering techniques and studying bacterial evolution.
For foreign DNA to be integrated, it typically undergoes recombination with the bacterium's chromosomal DNA. This process is often governed by specific enzymes that facilitate pairing and exchanging of genetic material. Without integration, as seen in abortive transduction, the DNA simply exists within the cell but cannot alter the host's traits or functions significantly. This can pose a limitation in harnessing new traits or abilities like galactose metabolism.
- Integration is crucial for stable genetic expression.
- Recombination ensures DNA is properly aligned within the host genome.
- Lack of integration results in a non-functional state for the DNA.
Thus, understanding the factors influencing DNA integration is vital for exploiting genetic engineering techniques and studying bacterial evolution.