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Protozoans lecture notes.docx

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ProtozoansProtozoansAnimal like protistsObligate heterotrophs these protists must consume foodThey live in a world with a very ideal surface to volume ratio When an organism is extremely small it has a very high surface to volume ratio This is really important because the biochemical processes that run their lives happen in the solution within the cell There may be may organelles and there may be compartmentalized Nutrients energy oxygen and when we generate nitrogenous waste it needs to be gotten rid of so we dont poison the organism And all of the supply and demand is met through the surface of the cell So when you have a very high surface to volume ratio it means that the activities and the biochemical processes happening within the cell can draw upon the huge exchange surfaces with the environment around it to meet its needs And as an organism gets bigger and bigger the Surface to volume ratios begin to decrease if we were to use simple surfaces to exchange The organisms have a variety of ways to overcome these problems They increase their surface to volume ratios by infolding membrane eg Lungs Protists living in a very ideal world because they are able to take many of the processes that they do and carry them out by simple diffusionOxygen diffused in and Nitrogen waste diffused out The water balance doesnt work for fresh water protists because they are going to inundated by water that moves into them Phagocytosis they are just going to engulf on their own food particles that are thereThey are going to consume their food and put it inside their food vacuole The intake of food is in some kind of particulate form and it isnt dissolved When we digest it we want to get it into a soluble form so we can digest it and use the enzymes to break it down and be able to carry out nutritionPinocytosisIntake of nutrients that are dissolved in water Intake of full range of nutrients so long as they are in liquid form they are able to consume this You get a much smaller vacuole in comparison to phagocytosisWhat happens to the food vacuole in all of the protozoansGiant food vacuole that has a nice chunk of food inside it and it is surrounded by plasma membrane because it was generated by phagocytosis and that plasma membrane is important because it is semipermeable and doesnt allow big things through We have to break the particulate foods into smaller components so that the cytoplasm can utilize it Breaking down macromolecules to their monomers to make them accessible by the cell Breaking down Proteins to amino acids Carbohydrates to simple sugarLysozymes are filled with digestive enzymes that help break the polymers into their constituent monomers Proteins broken down by proteases into amino acids carbohydrases that break down carbohydrates lipases that break down lipids and nucleases that break down DNAchunks into nucleotides that you can useLysozymes contain a varied amount of enzymes that have the function of breaking down pretty much everythingWe need these enzymes partioned away and protected in such a way that they dont start autodigesting the cell That is why the Lysozyme is surrounded by a semi permeable bilipid layer Right after the food vacuole is consumed it fuses with a lysozomes and now we take all of those proteins that are destructive and can break down all of those complex molecules and youve inserted them into the food vacuoleThe enzymes now slowly chip away at the macromolecules into their smallest constituents and slowly diffuse out of the food vacuole We protected the cell itself from self distruction because its all wrapped up in this membrane and the enzymes can never get out Slowly over time we get disgestion and the nutrients and the monomers released and as the vacuole travels around the cell it will slowly distribute nutrients to all parts of the cell In most protists we have a region that we get the food vacuoles forming all the timeCytostome In most protists this is a very special site where they make a food vacuole Its not a mouth CytocellStomemouthThat vacuole is going to travel around and we will reach a point where there is nothing more to be digested and we will need to remove undigested residue Cytoproct cell anusQuite often there is a place where we release the undigested residueThe composition of the food vacuole changes so when the food vacuole is formed and it first starts digestion it digests in an acidic environment ACID OPTIMAL and after all the acid like enzymes have had a go at it the enzymes composition changes in the food vacuole and it switches to alkaline digestion Because we do digestion in both acidic and alkaline conditions we are guaranteed to break down everything that is there because when we digest we need to unfold the protein unfold the nucleic acid we need to denature the carbohydrates and if there is any ionic digestion going on If you digest in only an acid environment you unfold some bonds onlyInitial acid and eventual alkaline digestion happens in the stomach of all animals Stomach is acidic and the intestinal tract is alkalineAs the vacuole moves along its bleeding out nutrients and acting as a distributive system to make sure everyone gets somethingCytoplasm is always moving aka cytoplasmic streaming helps move the vacuole movementMovementTypes of movements PseudopodsFleshy extensions of the amoebaUndulipods 92 movement of the cilia or the flagellaNo movement parasitic forms only move around by the motion of the host that they are infecting
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