Biological Sciences
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.
Written by Perlego with AI-assistance
Related key terms
1 of 5
3 Key excerpts on "Bacteria Reproduction"
eBook - ePubMolecular Biology
Academic Cell Update Edition
- David P. Clark(Author)
- 2012(Publication Date)
- Academic Cell(Publisher)
18 Bacterial GeneticsSummary
Bacteria have a different type of life cycle than us humans, making research on bacteria very easy. Most of the time, bacteria reproduce by binary fission where they replicate their single chromosome, they elongate their cell, and then they form a wall between the two halves to form two identical daughter cells. This is asexual or vegetative reproduction because no genes are exchanged, and the daughter cells have identical genetic make-up as the original parent. Bacteria also have the ability to have sexual reproduction that does exchange genes to create daughter cells with new genetics. Rather than male and female, the sexual reproduction occurs with a donor cell that gives its DNA to a recipient cell that receives the DNA.There are three different mechanisms for new genes to be added to bacteria: conjugation, transduction, and transformation. Transformation is the transfer of naked DNA from the environment into the bacterial cell. Transformation only occurs in competent bacteria, so this technique occurs only under certain circumstances in the environment, and it is mainly exploited by researchers in the laboratory. In the environment, transformation happens when bacteria of the same kind reach a certain density and release pheromones that induce expression of DNA uptake proteins. In the lab, transformation occurs because the cell wall and membrane are damaged, and DNA is able to get into the cytoplasm. Basically, bacteria are made competent by chilling them in the presence of calcium ions which loosens the structures of their cell wall and membrane. Heat shock then disrupts the wall and membrane and allows the DNA into the cytoplasm. Alternatively, bacteria are made competent by electroporation, where a high voltage shock induces the bacteria to take up naked DNA. The DNA taken up by competent bacteria must have an origin of replication for it to survive as the bacteria grow, so usually plasmids are used in transformation. If linear pieces of DNA are transformed into bacteria, these can only survive cell division if they have regions that are homologous to the bacterial chromosome. On rare occasions, the homologous regions will line up, and recombination will replace the bacterial chromosome region with the linear transformed DNA. Recombinants will then have the transformed linear DNA. When naked viral DNA is used in transformation, bacterial scientists call this transfection. (Note: The term, transformation, can also mean changing normal cells into cancer cells, and the term, transfection, can also mean the artificial introduction of foreign DNA into cultured animal cells.)
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 SequencingReproduction 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. However, mechanistically it is very different. Consequently, some scientists regard bacterial gene transfer as a primitive or aberrant form of sex, whereas others believe that it is quite distinct and that use of the same terminology is misleading.
eBook - PDF- Ulrich Drews(Author)
- 2018(Publication Date)
- Thieme(Publisher)
B. Sexuality in Bacteria Sexuality may have originated as a mecha-nism of gene recombination, as ex-emplified in bacteria by the modified mode of infection used by bacteriophages. 1. Infection. Bacteria possess a ring chro-mosome of DNA. Ba cteriophages are viral parasites of bacteria that can inject their DNA into a bacterial cell through a sex pilus. Inside the bacterium, synthesis of viral proteins proceeds until the bac-terium undergoes lysis. 2. Transfection. Alternatively, after injec-tion into the bacterium, the viral DNA may remain in the form of a ring-shaped plasmid. These plasmids often encode im-portant genetic information for bacteria, such as resistance to antibiotics. Plasmids are passed on to other bact er ia by transfec-tion, a modified mode of infection involv-ing the sex pili , which are encoded by the plasmid. 3. Conjugation. If the plasmid is inte-grated into the bacterial ring chromo-some, the entire ring chromosome can be transferred to another bacterium of the same species via the sex pili. The ho-mologous ring chromosomes pair, and crossing over and recombination of genes can occur. In the ensuing cell division, unequal daughter cells are generated. One of the two daughter cells carries the genes encod-ing the sex pili, i. e. , the male determi-nants necessary for conjugation. This mechanism corresponds to the species-specific adhesion of sperm to the zona pe l-lucida, leading to the fusion of sperm with the membrane of the oocyte(--> 1.14 A4). 1.1 Life Cycle B. Sexuality in bacteria 5 Individual and germ line 7 Mitosis DNA synthesis 5 Meiosis Recombination Pairing DNA synthesis Germ cells Somatic cells 4 Individual 6 Gametes Diploid phase Haploid phase Primordial germ cells 3 Embryo 1 Fertilization 2 Zygote A. Life cycle Bacterio-phage 1 Infection Phage DNA Ring-chromosome Bacterium Plasmid Sex pilus 2 Transfection 3 Conjugation “Male” determinant Incorporation in the ring chromosome Cross-over and recombination Division
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
