by Vincent Racaniello, PhD

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    Hello and welcome to Bacteria. My learning goals for Bacteria include, you'll understand the differences between gram positive and gram negative bacteria. You will appreciate how microbes take up substances from their environment. You'll be familiar with components of bacterial cells. You will have an overview of the metabolic capabilities of bacterial cells. And perhaps most importantly, you'll have a newfound appreciation for all that bacteria can do. Let's start with a little review of what we know about bacteria. Here's an electron micrograph of a common bacterium from your intestine, E. coli. These are rod shaped cells and they're magnified about 100,000 times. Bacteria, in contrast to the cells that make us up, eukaryotic cells, bacteria have no nuclei and no membrane-bound organelles like mitochondria or chloroplast. They form spheres, rods and spirals, so they look differently under the microscope. And remember they're found everywhere on earth, not just in you and on you, but in every animal that exists, in the oceans, the soils and even the skies. And remember the number of bacteria on earth is an impressive number, 5×10 to the 30th; they outnumber every living thing on the planet. So let's take a look in more detail now at the structure of bacteria. In the inside of every bacteria cell is the cytosol, which is a fluid phase medium that contains a lot of the activity of the bacteria. The nucleic acid, the DNA of a bacteria is present in the structure called the nucleoid. The cytoplasm of bacteria also contains ribosomes, these are the places where protein synthesis occurs and many bacteria have plasmids, these are small pieces of DNA, they are often circular that are apart from the main chromosome of the bacteria. Surrounding this cytosol is what we call a cell membrane,...

    About the Lecture

    The lecture Bacteria by Vincent Racaniello, PhD is from the course Microbiology: Introduction. It contains the following chapters:

    • Bacteria and Bacterial Structure
    • The Gram-positive Solultion
    • The Gram-negative Solution
    • The Bacterial Interior
    • Making a Bacterial Cell
    • Fueling in Heterotrophs
    • Harnessing Bacteria
    • Bacteria Exchange DNA

    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.

    Author of lecture Bacteria

     Vincent Racaniello, PhD

    Vincent Racaniello, PhD

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    thanks very much sir,the …
    By Ibrahim M. on 01. June 2016 for Bacteria

    thanks very much sir,the lecture is very helpful