How Do Bacteria Share Genes? Mechanisms of Genetic Exchange
Hereditary recombination is the other name of genetic exchange. It is the exchange of genetic information between various living beings which prompts the creation of organisms with mixes of characteristics that vary from those found in one or the other parent. In eukaryotes, the transfer of genetic information during meiosis can prompt a novel arrangement of hereditary data that can be given from the guardians to posterity. Most recombination is normally happening at the time of cell division.
During meiosis in eukaryotes, hereditary recombination includes the blending of homologous chromosomes. This might be trailed by data move between the chromosomes. The data move may happen without actual exchange in which a segment of hereditary material is replicated, starting with one chromosome then onto the next, without the donor chromosome being changed or by the breaking and rejoining of DNA strands, which shapes new atoms of DNA. We will learn about gene transfer in bacteria and how the genetic material of bacteria is replicated and exchanged.
Recombination
Recombination is an exchange of genetic information that may happen during mitosis in eukaryotes where it usually includes the two sister chromosomes framed after chromosomal replication. For this situation, new blends of alleles are not created since the sister chromosomes are normally indistinguishable. In meiosis and mitosis, recombination happens between comparative atoms of DNA that are homologous successions. In meiosis, non-sister homologous chromosomes pair with one another so recombination typically happens between non-sister homologs. In both meiotic and mitotic cells, recombination between homologous chromosomes is a typical system utilized in DNA fix.
Bacterial Recombination
Bacterial recombination is a kind of hereditary recombination in which the genetic material of bacteria is exchanged with one organic entity called the donor and onto the next organic entity known as a receiver. Gene transfer in bacteria can take place in three ways:
Transduction
Transformation
Conjugation
Recombination in microbes or gene transfer in bacteria is catalyzed by a recombinase enzyme. These recombinases fix the DNA that is harmed by homologous recombination. The capacity to go through normal change is available at any rate in 67 bacterial species. Natural change is regular among pathogenic bacterial species. The DNA fixability is given by recombination, and it works with the endurance of the contaminating bacterial pathogen. The exchange of genetic material of bacteria is completed by various cooperating bacterial quality products.
Bacterial Transformation
A question arises, that does bacteria have DNA? Yes, DNA is the genetic material in bacteria. Bacterial transformation is an interaction or exchange of genetic material in bacteria. It is a process by which a few microorganisms take up unfamiliar hereditary material from the environment. It was first demonstrated in Streptococcus pneumoniae by Griffith in 1928. It is essential for microorganisms to go through a change in their capacity to take up free, extracellular hereditary material. Such microorganisms are named equipped cells. When the recombinant element that is the DNA enters the cytoplasm, it could be debased by nucleases in the event, and then it is not quite the same as the bacterial DNA. In the event that the exogenous hereditary material is like bacterial DNA, it might incorporate into the chromosome. Some of the time the exogenous hereditary material may exist together as a plasmid with chromosomal DNA.
The Uses of Recombination Technique in Bacteria are:
To make numerous duplicates of the DNA in cloning techniques
To communicate a lot of proteins and chemicals
In the formation of microscopic organisms
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Bacterial Conjugation
Bacterial conjugation is the exchange of hereditary material between bacterial cells by direct cell-to-cell contact or by an extension of some organs between two cells. This happens through a pilus. It is a parasexual method of multiplication in microorganisms. Traditional Escherichia coli bacterial formation is frequently viewed as what could be compared to sexual generation or mating in humans since it includes the trading or exchange of hereditary material. In any case, it is not sexual propagation, since no trade of gamete happens. During Escherichia coli formation, the donor cell gives a conjugative or mobilizable hereditary component that is regularly a plasmid or transposon. Most conjugative plasmids have frameworks guaranteeing that the beneficiary cell does not contain a comparable component. The hereditary data that is moved is regularly helpful to the beneficiary. Advantages may incorporate anti-toxin opposition, xenobiotic resilience, or the capacity to utilize new metabolites. Other components can be inconvenient and might be seen as bacterial parasites.
The Process of Conjugation Can be Seen as:
The donor cell produces pilus.
The pilus connects to the beneficiary cell and unites the two cells.
The portable plasmid is scratched and a solitary strand of DNA is then moved to the beneficiary cell.
The two cells orchestrate a correlative strand to deliver a twofold round plasmid and furthermore replicate pili. These are the two cells that are currently feasible donors for the F-factor.
A cell culture that contains non-incorporated F-plasmids typically contains a couple of cells that have unintentionally coordinated their plasmids. It is these cells that are liable for the low-recurrence chromosomal quality exchanges that happen in such cases. A few strains of microbes with an incorporated F-plasmid can be disconnected and filled in unadulterated culture. Since such strains move chromosomal qualities productively they are called Hfr (high recurrence of recombination). The E. coli genome was initially planned by intruded on mating tests in which different Hfr cells during the time spent formation were sheared from beneficiaries after under 100 minutes. The qualities that were moved were then explored. Since mixing of the F-plasmid into the E. coli chromosome is an uncommon unconstrained event, and since the various qualities of advancing DNA move are in the plasmid genome as opposed to in the bacterial genome, it has been contended that conjugative bacterial quality exchange, as it happens in the E. coli Hfr framework, is certifiably not a transformative variation of the bacterial host, nor is it likely familiar to eukaryotic sex.
Bacterial Transduction
Transduction is the interaction by which unfamiliar DNA is brought into a cell by an infection or viral vector. Transduction does not need actual contact between the cell giving the DNA and the cell accepting the DNA. Transduction is a typical apparatus utilized by atomic scholars to steadily bring an unfamiliar quality into a host cell's genome. It can be both bacterial and mammalian cells.
Generalized Transduction
It happens when arbitrary bits of bacterial DNA are bundled into a phage. When a phage is in the lytic stage, that moment the viral DNA is bundled into phage heads. Generalized transduction may happen through recombination. Generalized transduction is an uncommon phenomenon and happens on the request for 1 phage in 11,000 phages. The new infection container that contains a part of bacterial DNA at that point contaminates another bacterial cell. At the point when the bacterial DNA is bundled into the infection, it is then embedded into the beneficiary cell and three things can happen to it:
The DNA is reused or recycled for spare parts.
If the DNA was initially a plasmid, it will re-circularize inside the new cell and become a plasmid once more.
If the new DNA matches with a homologous district of the beneficiary cell's chromosome, it will trade DNA material like the activities in bacterial recombination.
FAQs on Exchange of Genetic Information: Transformation and Transduction
1. What is meant by the exchange of genetic information in bacteria?
The exchange of genetic information in bacteria, also known as Horizontal Gene Transfer (HGT), is a process where an organism transfers genetic material to another cell that is not its offspring. Unlike vertical transfer (from parent to child), this allows bacteria to acquire new traits quickly. The primary mechanisms for this exchange are transformation, transduction, and conjugation.
2. What is bacterial transformation?
Bacterial transformation is a mode of genetic exchange where a recipient bacterium takes up fragments of naked DNA directly from its environment. This DNA often comes from lysed (broken-down) bacterial cells. For this to occur, the recipient cell must be in a physiological state called competence, where its cell wall is permeable to the foreign DNA.
3. What is bacterial transduction?
Bacterial transduction is a process where bacterial DNA is transferred from a donor bacterium to a recipient bacterium by a virus, known as a bacteriophage. The bacteriophage acts as a vector, accidentally packaging bacterial DNA into its viral head and injecting it into the next bacterium it infects. This DNA can then be incorporated into the recipient's genome.
4. What is the key difference between transformation and transduction?
The fundamental difference lies in the mechanism of DNA transfer. In transformation, the recipient cell actively takes up free-floating DNA from the environment. In contrast, transduction is a passive process for the bacterium, as it relies on a bacteriophage (virus) to act as an intermediary that injects the donor DNA into the recipient cell.
5. Can you provide an example of transformation in bacteria as per the CBSE syllabus?
The classic example of transformation is Frederick Griffith's experiment (1928) with Streptococcus pneumoniae. He observed that when a live, non-virulent R-strain of bacteria was mixed with heat-killed, virulent S-strain bacteria, the R-strain was 'transformed' into the deadly S-strain. This happened because the live R-strain bacteria took up the genetic material (the 'transforming principle') from the dead S-strain cells in the environment.
6. What distinguishes generalized transduction from specialized transduction?
These are two types of transduction that differ in the DNA they transfer:
Generalized Transduction: During the lytic cycle, any random piece of the host bacterium's DNA can be accidentally packaged into a new phage. This means any bacterial gene can potentially be transferred.
Specialized Transduction: This occurs during the lysogenic cycle. When the prophage (viral DNA integrated into the host chromosome) is excised, it may incorrectly take a specific, adjacent piece of the bacterial chromosome with it. Therefore, only genes located near the viral integration site can be transferred.
7. How does a bacterium become 'competent' to undergo transformation?
A bacterium achieves competence, the ability to take up external DNA, through specific physiological changes. This state can be triggered naturally by environmental stressors like nutrient limitation, leading to the production of proteins that alter the cell membrane and wall to allow DNA entry. In a laboratory setting, competence can be induced artificially using techniques like calcium chloride treatment or electroporation, which create temporary pores in the cell envelope.
8. Why is horizontal gene transfer, including transformation and transduction, so important for bacterial evolution?
Horizontal gene transfer is a powerful evolutionary engine for bacteria because it allows for the rapid acquisition of new genetic traits, bypassing the slower process of random mutation. This is crucial for adaptation to new environments. For instance, a bacterium can acquire genes for antibiotic resistance, virulence factors, or new metabolic pathways from another bacterium, significantly enhancing its survival and spread.
9. Could transformation or transduction lead to the spread of antibiotic resistance?
Yes, absolutely. Both processes are major contributors to the spread of antibiotic resistance. Resistance genes are often located on mobile genetic elements like plasmids or within the bacterial chromosome. When a resistant bacterium dies, its DNA can be taken up by other bacteria via transformation. Similarly, a bacteriophage can transfer these resistance genes from one bacterium to another via transduction, leading to the rapid emergence of multi-drug resistant strains, or 'superbugs'.
