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Bacteria Exchange DNA – Bacteria

by Vincent Racaniello, PhD
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    00:00 a product of bacterial fermentation. Another very important property of bacteria is that they readily exchange DNA. They actually have sex. And here is one way that they can do this, it's called transformation. DNAs can go from one bacteria to another. If they have two different bacteria, they have two different DNAs as part of their chromosomes.

    00:23 Here the DNA is shown coming into the bacteria from another one and it eventually integrates into the chromosomal DNA and whatever gene that is can contribute to the bacteria’s well-being. Bacterias also conjugate, so here we show bacteria with a big chromosomal DNA and a smaller plasmid. These plasmids can be transferred from bacterium to another bacterium through those pili which I described earlier, those pili which help the bacteria move and which help them attach, they can also act to transport DNA, so the result is, if this plasmid has a gene encoding, an enzyme that's useful for the bacteria or even antibiotic resistance, this can transfer from cell to cell. And finally the viruses that infect bacteria, what we call bacteriophages, can pick up bacterial DNA and move it from cell to cell. In this example we see a bacteriophage infecting a bacterium and eventually killing it, in the process the bacteriophage causes the bacterial DNA to be chopped up into pieces. As the new viruses are formed, of course they have viral DNA in them, but a few of them actually pick up pieces of these broken down bacterial DNA and so when those viruses infect a new cell, they give it a new piece of bacterial DNA, they can give it new properties. This is why the bacterial world in part is so diverse, because bacteria are really good at exchanging genetic information.

    02:00 So I hope today that you've learned a number of things. Among them, the differences between gram-positive and gram-negative bacteria, how microbes take up substances that they need from the environment. I hope that you're familiar with components of bacterial cells that are important for growth. I hope you have an overview of the metabolic capabilities of bacteria and how remarkable these bacteria are and how they benefit the earth and benefit us. And finally I do hope you have a newfound appreciation for everything that bacteria can do and don't just think about them as making you sick, but think about all the ways that can help you.

    02:41 Thanks for listening and we'll see you next time.


    About the Lecture

    The lecture Bacteria Exchange DNA – Bacteria by Vincent Racaniello, PhD is from the course Microbiology: Introduction.


    Included Quiz Questions

    1. The murein or the thick peptidoglycan layer passes the necessary molecules because they are hydrophilic.
    2. The outer membrane has pores in it that will allow small hydrophilic compounds to diffuse through.
    3. Large complexes get moved through transport complex proteins that are embedded in the membrane.
    4. Periplasmic spaces contain enzymes that can digest material as it comes through the outer membrane and transport it further on.
    5. The inner cell membrane has transport mechanisms that allow any materials that have been brought in to then get into the cytosol of the bacteria.
    1. It rotates like a fan and propels the bacteria forward and backwards based on energy stores and cellular nutrient requirements.
    2. It is usually made of amino acids or sugars.
    3. It's a determinant of the ability to colonize a specific niche, such as an organ or an outside environment.
    4. It protects the cell from drying out or desiccating.
    5. It is a defense mechanism against immune attack in that it protects from phagocytic cells which often try to engulf bacteria.
    1. Oxaloacetate and pyruvate.
    2. Carbon dioxide and lactate.
    3. Oxaloacetate and lactate.
    4. Pyruvate and carbon dioxide.
    5. Lactate and pyruvate.
    1. Pili
    2. Cell wall
    3. Cell membrane
    4. Cytosol
    5. Nucleotide
    1. Loose DNA exchange
    2. Plasmid exchange
    3. Plasmid evacuation
    4. Loss of DNA
    5. Growth of cell

    Author of lecture Bacteria Exchange DNA – Bacteria

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD


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