Bacteria Reproduction
Bacteria reproduce through a process called binary fission, where a single bacterial cell divides into two identical daughter cells. This asexual reproduction allows bacteria to rapidly increase in number under favorable conditions. Some bacteria can also exchange genetic material through a process called conjugation, which contributes to genetic diversity within bacterial populations.
6 Key excerpts on "Bacteria Reproduction"
eBook - ePub- Britannica Educational Publishing, Kara Rogers(Authors)
- 2010(Publication Date)
- Britannica Educational Publishing(Publisher)
...Different serovars of these enteric bacteria are often found to be associated with the ability to inhabit different host animals or to cause different diseases. Formation of these numerous serovars reflects the ability of bacteria to respond effectively to the intense defensive actions of the immune system. BACTERIAL REPRODUCTION Bacteria can reproduce in various ways. The most basic process is known as binary fission, which is characterized by bacterial cell growth and DNA replication that results in the splitting of one cell into two cells. This mode of reproduction produces two daughter cells that are identical to that of the parent cell. Binary fission alone, however, provides little benefit in the way of maintaining genetic diversity, which is important for the long-term success and evolution of species of bacteria. In most animals and in certain plants, genetic variation within a species is frequently the result of sexual reproduction, in which the recombination of genes from two parent organisms produces a genetically distinct offspring. In the absence of sexual reproduction, bacteria have evolved multiple methods to secure opportunities for genetic recombination, both within and between species. This enables the organisms to incorporate new genes into their genomes. However, while genetic exchange drives the perpetual evolution of bacteria, allowing the organisms to adapt in response to new conditions, it also underlies the phenomenon of antibiotic resistance, which has become a significant concern in the medical treatment of bacterial infection. R EPRODUCTIVE P ROCESSES Asexual reproduction, in the form of binary fission, budding, or sporulation, represents the primary mode of reproduction utilized by bacteria. Asexual reproduction is augmented by genetic exchange, which occurs via three different mechanisms: transformation, transduction, or conjugation...
eBook - ePub- David P. Clark(Author)
- 2009(Publication Date)
- Academic Cell(Publisher)
...Chapter Eighteen Bacterial Genetics Reproduction versus Gene Transfer Fate of the Incoming DNA after Uptake Transformation is Gene Transfer by Naked DNA Transformation as Proof that DNA is the Genetic Material Transformation in Nature Gene Transfer by Virus—Transduction Generalized Transduction Specialized Transduction Transfer of Plasmids between Bacteria Transfer of Chromosomal Genes Requires Plasmid Integration Gene Transfer among Gram-Positive Bacteria Archaebacterial Genetics Whole Genome Sequencing Reproduction versus Gene Transfer Sex and reproduction are not at all the same thing in all organisms. In animals, reproduction normally involves sex, but in bacteria, and in many lower eukaryotes, these are two distinct processes. Bacteria divide by binary fission. First they replicate their single chromosome and then the cell elongates and divides down the middle. No resorting of the genes between two individuals (that is, no sex) is involved and so this is known as asexual or vegetative reproduction. In bacteria, cell division and the re-assortment of genetic information are completely separate processes. From a biological perspective, sexual reproduction serves the purpose of reshuffling genetic information. This will sometimes produce offspring with combinations of genes superior to those of either parent. Although bacteria normally grow and divide asexually, gene transfer may occur between bacterial cells. During sexual reproduction in higher organisms, germ line cells from two parents fuse to form a zygote that contains equal amounts of genetic information from each parent. In contrast, in bacteria gene transfer is normally unidirectional and cell fusion does not occur. Genes from one bacterial cell are donated to another. We thus have a donor cell that donates DNA and a recipient cell that receives the DNA. The transfer of genes between bacteria fulfils a similar evolutionary purpose to the mingling of genes during sexual reproduction in higher organisms...
eBook - ePub- Jeremy W. Dale, Simon F. Park(Authors)
- 2013(Publication Date)
- Wiley(Publisher)
...6 Gene Transfer The concept of the reassortment of characteristics through sexual reproduction in animals and plants was a familiar one long before Mendel put it on a scientific footing. Not only do the features of individuals represent a combination of those of their parents (or grandparents), but the phenomenon has been used over the centuries to establish new strains of plants and animals that combine the best characteristics of different strains. How can we apply the same concept to organisms such as bacteria that do not exhibit sexual reproduction? We now know that bacteria do exchange genetic information, not only in the laboratory but also in nature. There are three fundamentally distinct mechanisms by which such genetic transfer can occur: 1 transformation, in which a cell takes up isolated DNA molecules from the medium surrounding it; 2 conjugation, which involves the direct transfer of DNA from one cell to another; 3 transduction, in which the transfer is mediated by bacterial viruses (bacteriophages). Not all bacterial species exhibit all of these modes of genetic transfer. Conjugation is most readily demonstrated in Gram-negative bacteria but does occur in some Gram-positive genera such as Streptomyces and Streptococcus. Although some important bacterial species are naturally transformable, in many other species transformation is only readily demonstrated after some form of artificial pre-treatment of the cells, and therefore probably does not occur naturally in those organisms. These mechanisms differ from true sexual reproduction in two main respects: there is no link with reproduction, and the genetic contribution from the parents is unequal...
eBook - ePub- Volodymyr Ivanov(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
...8 Reproduction, Proliferation, and Growth Reproduction of Viruses The reproduction of viruses is defined as an increase in the number of viral particles. There are six basic stages in viral reproduction: 1. attachment: a specific binding between virus and host cell, determining the host range of the virus 2. penetration: when the attached virus enters the host cell 3. uncoating: when the viral envelope is degraded, thus releasing the viral nucleic acid 4. replication: synthesis of viral nucleic acid and protein 5. self-assembly of the virus particles 6. lysis of the host cell and the release of viruses Reproduction of Prokaryotes Reproduction is defined as an increase in the number of cells. Growth is defined as an increase in biomass. The most common method of cell reproduction in Bacteria and Archaea groups is an increase in cell volume, followed by the binary fission of the adult cell to two almost equal daughter cells (Figure 8.1). FIGURE 8.1 Reproductive cycles of (a) rod-shaped and (b) spherical prokaryotic cell by binary fission. Other, less common methods of cell reproduction include multiple fission or budding (Figure 8.2). In this case, mother and daughter cells have quite different sizes, shapes, and other properties. FIGURE 8.2 Reproductive cycles of prokaryotic cells with multiple fission (a and b) or budding (c). The bud is formed on a mother cell. The bud then grows and is transformed into a daughter cell that is separated from the mother cell. Vegetative Reproduction of Microscopic Eukaryotes The reproduction of microscopic eukaryotes is either performed by vegetative reproduction, which starts with the growth of cell biomass and is followed by the separation of mother and daughter cells, or by other methods of asexual and sexual reproduction. For example, vegetative reproduction of mycelial fungi takes place by the elongation and separation of cells at the tip of the hyphae...
eBook - ePubAdvanced Molecular Biology
A Concise Reference
- Richard Twyman(Author)
- 2018(Publication Date)
- Garland Science(Publisher)
...Chapter 10 Gene Transfer in Bacteria Fundamental concepts and definitions Gene transfer describes the introduction of genetic information into a cell from an exogenous source (ultimately, another cell). This process occurs naturally in both bacteria and eukaryotes, and may be termed horizontal or lateral genetic transmission to distinguish it from the transmission of genetic information from parent to offspring, which is vertical genetic transmission. Intraspecific gene transfer facilitates genetic mixing in asexual species and thus mimics the effects of sexual reproduction. Such parasexual exchange mechanisms have been exploited to map prokaryote genomes analogously to meiotic mapping (q.v.) in eukaryotes. Interspecific gene transfer can also occur, and is a natural mechanism of transgenesis (q.v.). Interspecific gene transfer is an important evolutionary process and has been responsible for some of the most fundamental evolutionary events (e.g. the endosymbiont origin of eukaryotic organelles) as well as facilitating specific interactions between bacteria and eukaryotes (e.g. tumor-induction by Agrobacterium tumorfaciens; q.v. Ti plasmid). The source of the transferred information is the donor and the genetic information transferred is the exogenote (exogenous genome, usually only a fragment of the donor genome). The target of the gene transfer, the recipient, possesses the endogenote (endogenous genome). If the exogenote is homologous to part of the endogenote, gene transfer will make the recipient cell partially diploid (a merozygote), in which case recombination can occur, which may involve allele replacement (marker exchange). There are four major mechanisms of gene transfer in bacteria: cell fusion, conjugation, transformation and transduction (Table 10.1). All cases of gene transfer must involve introduction of DNA into the recipient and a resolution phase, where the fate of the exogenote is determined...
eBook - ePub30-Second Biology
The 50 most thought-provoking theories of life, each explained in half a minute
- Nick Battey, Mark Fellowes, Nick Battey, Mark Fellowes(Authors)
- 2018(Publication Date)
- Ivy Press(Publisher)
...Some bacteria, however, form stable associations with other bacterial species to form a ‘biofilm’, a kind of self-sufficient ecological community in which different species recycle the wastes of others. Biofilms are found in, for example, dental plaque, and also the lungs of patients with cystic fibrosis, and are very hard to remove. When confronted by hard times, some kinds of bacteria such as Clostridium tetani, which causes tetanus, form a different kind of structure – an inert and resistant state called a spore. Because it forms a distinct kind of cell, spore formation is just about the only process that counts as ‘development’ in bacteria. 3-SECOND DISSECTION Like most single-celled organisms, bacteria multiply by dividing; although their potential for individual development is limited, communication and genetic exchange between individuals causes differentiation within communities. 3-MINUTE SYNTHESIS Bacterial life isn’t completely sexless. Sometimes bacteria extend tubes called ‘pili’ to one another, through which they exchange DNA. In addition to their chromosomes, bacteria may host smaller pieces of DNA called plasmids. These are important as they may contain genes that confer antibiotic resistance or other traits, like the ability to fix nitrogen. In general, bacteria are liberal with their DNA, scavenging it from the environment and donating it to one another. RELATED TOPICS See also ARCHAEA BACTERIA MUTUALISMS 3-SECOND BIOGRAPHIES OSWALD AVERY 1877–1955 American biologist who in 1944, with colleagues Colin MacLeod and Maclyn McCarty, showed that live bacteria scavenged DNA from dead cells, proving that DNA was the hereditary material STANLEY N. COHEN 1935– American geneticist who, with Herb Boyer and Paul Berg, discovered how to use bacterial plasmids to transfer DNA from one organism to another, so inventing genetic engineering 30-SECOND TEXT Henry Gee Bacteria such as E...
