Week 1 of Exam 2 Notes of Microbiology -Cell/Bacteria structure and function
Week 1 of Exam 2 Notes of Microbiology -Cell/Bacteria structure and function 81382 - MICR 3050 - 001
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This 3 page Class Notes was uploaded by Katie Kessler on Tuesday September 22, 2015. The Class Notes belongs to 81382 - MICR 3050 - 001 at Clemson University taught by Dr. Rudolph in Summer 2015. Since its upload, it has received 348 views. For similar materials see General Microbiology in Biological Sciences at Clemson University.
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Date Created: 09/22/15
Week 1 of Exam 2 notes 3135 Bacterial cell structure and function The structure of LPD consists of Lipid A core polysaccharides and an 0 side chain 0 antigen Lipid A is embedded in the outer membrane while the core polysaccharide and 0 side chain extend out from the cell The importance of LPS consists of the negative charge on the cell surface and Lipid A helps stabilize the outer membrane LPS creates a permeability barrier which keeps out toxins and keeps the consistent negative charge In addition LPS may mutate to protect from host defenses LPS can also act as an endotoxin Lipid A which means it can be poison when it needs to be Bacteria can survive without a cell wall in isotonic environments Protoplast remove gram positive membrane and spheroplasts remove the gram negative membrane Mycoplasmas are an example of a bacteria that can cause diseases without a cell wall They have a PM that is more resistant to osmotic pressure Capsules are usually composed of polysaccharides and are very organized making it uneasy to remove from the cell Protective features of capsules include being resistant to phagocytosis desiccation drinks the water or eats to survive and they can exclude viruses and detergents In addition to these advantages the polysaccharide is sticky which makes a great biofilm Slime molds are similar to capsules except they diffuse and are unorganized which means that they are easy to remove Slime molds often aid in motility and secretion It is important to note that phagocytosis doesn t work in slime molds 3639 Bacterial cell structure and function Cytoskeletal It forms a framework for the movement of organelles around the cytoplasm It includes protein microfilaments intermediate filaments and microtubules Proteins Proteins are large complex molecules that play many critical roles in the body They do most of the work in cells and are required for the structure function and regulation of the body s tissues and organs Cell inclusions stored nutrients secretory products and pigment granules Examples of storing energy like carbon you can store PHBglycogen for phosphate you can store polyphosphate granules and for sulfur you can store granules that assist in metabolism Lastly for Nitrogen storage you can use cyanophycin granules that store AA Other additional inclusions to be aware of are gas vacuoles that provide buoyancy and magnetsosomes which are used to magnetite particles for orientation in earths magnetic field They are also known as aggregates of organic or inorganic material granules crystals globules Some inclusions are enclosed by a single layer of membrane or invaginations of the PM however it is important to note that it is not an organelle bc they do not have a real function Flagella locomotion that often has function as a sensory organelle being sensitive to chemicals and temperatures outside the cell Endospores The primary function of most endospores is to ensure the survival of a bacterium through periods of environmental stress Flagella is a threadlike appendages extending outward from PM and cell wall Its functions include motility and a swarming behavior It attaches to surfaces which helps it to swim and helps it burrow It also has the ability to evade or cause disease Flagella can be monotrichous one flagellum polar flagellum flagellum at the end of the cell amphitrichous one flagellum at each end of the cell lophotrichous cluster of flagella at the end or both ends and lastly peritrichous spread over entire surface of the cell The structure of flagella consists of a tail which is the filament and it is made out of the protein The hook attaches the filament to the basal body and the basal body is the motor the 2 part motor produces torque which consists of the rotorC ring and MS ring and the statorMot A and Mot B proteins There are 4 layers of the flagella L ring LPS and P ring peptidoglycan don t spin These hold the flagellum in place The MS ring membrane supramembrane and the C ring cytoplasm spin The Mot proteins are stationary as well Cap proteins build the filaments The filament is built from the tip not the base bc it has to be in contact with the CAP proteins An important note to take in consideration is that the proton motive force spins the flagellum The ETC is in the cell membrane and during respiration it shuttles H on the outside of the cell and negative cells are on the inside This is the proton motive force This then gives you an electrochemicalpH gradient energy Dr Rudolph explains this as a cell going through a revolving door and as the door spins the rings spin Chemotaxis is the movement of an organism in response to a chemical stimulus Positive chemotaxis toward motion has lowered frequency of tumbles and the runs are longer Negative chemotaxis away consists of more tumbling and less runs Flagellum rotates like a propeller and move in a CCW direction called a run and move in a CW direction when it tumbles Spirochete motility form an axil fibril that winds around the cell not on the outside of the cell it is on the inside and the flagella remains in the periplasmic space inside the outer sheath while it moves in a corkscrew shape which exhibits flexing and spinning movements This is advantageous bc it can infect tissues and burrow in them Twitching motility the pili is at the ends of the cell and is short intermittent and involves jerky motions The cells are in contact with each other and the surface Gliding motility smooth movements that can occur with single cells or in a group of cells Some cells produce slime that help it move across a solid surface Bacterial endospore complex and dormant structure that is formed by some bacteria Endospores are located in various places bc they are resistant o numerous environmental conditions such as heat radiation chemicals and desiccation Just a fun fact about endospores all the bacteria that make spores are gram positive Bacterial endospore structure Endospores are resistant bc of their numerous layers which consist of an exosporium thin layer on the outside Coat quot39 50 layers of proteins that are impermeable to toxins in the environment The outer membrane lipid bilayer Cortex peptidoglycan less cross linked than the normal cell this is advantageous for the protection of the spore Core cytoplasm Endospore resistance The core is low in water contents which means that it is a protective formant layer that doesn t have much metabolic activity and enzymes don t work in this layer The calcium dipicolinate stabilizes the DNA SASPs saturate the DNA and are small acid soluble DNA binding proteins The core has a slightly lower pH quot7 and this disables the enzymes from working properly Sporulation making the spores when the cell stops dividing The process DNA becomes denser and the endospore septum grows AROUND the protoplast then dehydration occurs and the exposporium and coat layers form Germination is triggered by food heat water The spore starts swelling and ruptures the spore coat which allows the water to come in There is an increase in metabolic activity There is an emergence of a vegetative cell
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