Learning Goals MIC 220 – Flashcards
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Unlock answers| What is a Microbe? |
A microbe is considered any living organism that a microscope must be used to be seen. Bacteria, Archaea, and Eukarya (Algae, Fungi and Protists) make up the 3 domains of microbes. |
| The roles of microbes |
| Microbes support natural ecosystems, allow for immunization of diseases, are responsible for geochemical cycling, yogurt, alcohol, cheese and are present in many human functions such as digesting food (like the said yogurt). Microbes are considered the first line of defense for the human immune system (bacteria). |
| Archaea |
| A single celled organism that contains no nucleus or any other membrane bound organelles within their cells. |
| Bacteria |
Has a thick complex out envelope. Has a compact genome. Tightly coordinated cell functions.(Maximize reproductive potential with minimal resources) The model bacterial cell contains highly ordered cytoplasm in which DNA replication, RNA transcription, and protein synthesis occur coordinately.
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Biochemical Composition of Bacteria. Not the macromolecules and their hydrophobicity/hydrophilicity |
The composition consists of water, essential ions (such as potassium, magnesium, and chloride ions), small organic molecules (such as lipids, and sugars that are incorporated into cell structures and that provide nutrition by catabolism.)
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| The macromolecules of bacteria and their hydrophobicity/hydrophilicity |
Protein, Nucleic Acid, Lipids and Polysacharrides. The peptidoglycan is hydrophobic and is made up of the macromolecules polysacharrides and proteins (amino acids). Keeps the cell from being destroyed by osmosis. Lipids are hydrophobic. Nutrients may be stored in the cytoplasm in lipids. |
| Cell Wall |
The cell wall is a single molecule. The cell wall gives shape and rigidity to a bacterial cell and helps withstand pressure that can result from osmotic pressure. Also known as the sacculus and consists of a single interconnected molecule that encloses the entire cell. It is highly porous to ions and small organic molecules. Most cell walls are made of peptidogylcan which is a polymer of peptide linked chains of amino sugars. Peptidoglycan is unique to bacteria and is the same as murein. It consists of parallel polymers of disaccharides cross-linked with peptides of four amino acids called glycan chains. The glycan chains are linked by peptide cross-bridges. Consists of repeating units of the disaccharide composed of n-acetylglucosamine and n-acetlmuramic acid. The peptide extension can form cross bridges connecting parallel strangs of glycan. |
| Gram Positive |
Have a thick cell wall with multiple layers of peptidoglycan, interpenetrated by teichoic acids. No space appears between the peptidogylcan layers.
There is an additional protective layer known as the S-layer, a crystalline layer of thick subunits consisting of protein or glycoprotein. (also found in archaea and gram negative). |
| Gram Negative |
| There is a thin layer of peptidoglycan and is believed to be a single sheet. The peptidoglycan is covered by an outer membrane. The outer membrane confers defensive abilities. Between the outermembrane and the inner membrane is the periplasm. |
| Flagella |
| A tail like projection that protrudes from the body of a cell and acts as a mode of transport. An example was given in class showing that based on the motion of the flagella (clockwise or counter clockwise) the cell will run towards are away from nutrient source (respectively). Can be found in both prokaryotes and eukaryotes. |
| Nucleoid |
| is an irregularly-shaped region within the cell of prokaryoteswhich has nuclear material without a nuclear membrane and where the genetic material is localized. |
| Cytoplasmic Membrane |
| Is composed oa a phospholipid bilayer and thus has all the general functions of a cell membrane such as acting as a permeability barrier for most molecules and serving as the location for the transport of molecules into the cell. Functions as the energy conservation as the location which a proton motive force is generated. Unlike eukaryotes Bacteria can have a wide variety of fatty acids within their membranes. As a phospholipid bilayer, the lipid portion of the outer membrane is impermeable to charged molecules. Channels called porins are present in the outer membrane that allow for passive transport of many ions, sugars and amino acids across the outer membrane. The molecules are present in the periplasm. |
| Periplasm |
| The space between the inner cytoplasmic membrane and the external outer membrane of Gram negative bacteria. |
