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SEXUAL REPRODUCTION IN BACTERIA- AN OVERVIEW

Sexual reproduction in bacteria does not occur the way it does in plants and animals (there is no fusion of gametes). However, bacteria do perform “sexual-like” genetic exchange processes that allow them to mix and recombine DNA. This increases genetic variation and helps them adapt.

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PMAS Arid Agriculture University Rawalpidi Submitted by Laraib Saleem Submitted to Mam Aniee Zafar BS Biology ( Semester 5) 23-Arid-1898 Microbiology
2 REPRODUCTIO N OF BACTERIA
3 INTRODUCTIO N Bacteria are tiny single- celled organisms that reproduce mainly through fast and simple processes. Most bacteria use asexual reproduction, especially binary fission, where one cell divides to form two identical cells. Because this method is very quick, bacterial populations can grow rapidly. Besides this, bacteria also exchange genetic material through processes like conjugation, transformation, and transduction. These help them gain new traits and adapt to different conditions.
ASEXUAL REPRODUCTI ON SEXUAL REPRODUCTIO N N OF BACTERIA 🦠 (Increases number of cells ) Increases genetic variation )
ASEXUAL REPRODUCTION 5 Asexual reproduction means one parent cell divides to form new cells.It is fast, simple, and produces genetically identical offspring. It consists of following methods: • Binary Fission • Budding • Fragmentation
6 BINARY FISSION Steps 1. Cell Growth The bacterial cell absorbs nutrients and becomes larger. Cytoplasm and cell components increase. 2. DNA Replication The circular bacterial chromosome copies itself. Now the cell has two identical DNA molecules. 3. Segregation of DNA Each DNA molecule moves to opposite sides of the cell. Cell prepares for division. 4. Septum Formation The cell membrane and cell wall begin to pinch inward. A division wall or septum starts forming between the two halves. Binary fission is the main and most rapid method of bacterial reproduction.
7 WHY BINARY FISSION IS FAST? NO NEED FOR A PARTNER SIMPLE DNA QUICK DNA REPLICATION • SHORT GENERATION TIME (MINUTES TO HOURS) 5. Cell Splitting The septum completely forms. The parent cell divides into two daughter cells. Both new cells are genetically identical.
8 BUDDING (LESS COMMON ) A small outgrowth or bud appears on the parent cell.The bud grows and eventually separates to form a new bacterium.Seen in some species like Caulobacter. The bacterial filament breaks into pieces. Each piece grows into a new organism. Common in filamentous bacteria like Actinomycetes. The septum completely forms. The parent cell divides into two daughter cells. • Both new cells are genetically FRAGMENTATION CELL SPLITTING
9 SEXUAL REPRODUCTION Bacteria do not have true sexual reproduction (no gametes, no fertilization). But they perform genetic exchange through three processes: • Conjugation • Transformation • Transduction
10 CONJUGATION (GENE TRANSFER THROUGH PILUS) Steps 1. A donor cell (F⁺) has a plasmid called the F-factor. 2. Donor forms a pilus, a tube-like structure. 3. The pilus attaches to the recipient cell (F⁻). 4. A bridge forms between the two cells. 5. A copy of the plasmid is transferred into the recipient. 6. After transfer, the recipient Result No new cell is formed immediately. But genetic variation increases. This is the closest to sexual reproduction in bacteria. Requires direct contact between two bacterial cell.
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12 TRANSFORMATION (UPTAKE OF FREE DNA) Example Antibiotic resistance can spread through transformation. Bacteria take up naked DNA fragments from their surroundings. Steps 1. Other bacteria die and release DNA fragment. 2. A living bacterium absorbs these DNA pieces. 3. The DNA enters the cell and may join with the bacterial chromosome. 4. If stable, the bacterium now has new traits.
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14 TRANSDUCTION (DNA TRANSFER BY VIRUS) Steps 1. Virus infects bacterium A. 2. While making new viruses, some viral particles accidentally pack bacterial DNA. 3. These viruses infect bacterium B. 4. They deliver DNA from bacterium A to B. 5. This new DNA becomes part of B’s genome. Result •No new cell is formed. •But bacterium B gets new genetic properties. A bacteriophage (virus that infects bacteria) transfers DNA from one bacterium to another.
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16 DIFFERENCE Features Asexual Reproduction Sexual Reproduction Number of parents 1 2( donor and recipient) New cell formed? Yes No (only exchange of DNA) Speed Very fast Slower Main method Binary fission Conjugation, Transformation, Transduction
17 OVERVIEW Bacteria mainly reproduce through asexual methods, especially binary fission, where one cell divides into two identical cells. This simple and quick process allows bacterial populations to grow rapidly. Along with this, bacteria also perform genetic exchange through conjugation, transformation, and transduction. These processes do not produce new cells but help bacteria gain new genetic traits and adapt to different environments.