BIOL 1411 1st Edition Lecture 6Outline of Last Lecture I. Lipids ContinuedII. CellsIII. OrganellesOutline of Current Lecture I. CellsII. MembranesCurrent LectureI. CellsEndoplasmic reticulum- highest fraction of a cell’s membranes and fluidRough ER- contains many ribosomes for manufacture of proteins that will be part of endomembrane system or exportedSmooth ER- site of protein modification, glycogen degradation, lipid synthesis, and chemical detox (no ribosomes)The Golgi- flattened sacs of membranes, receives, modifies and packages proteins from RER, manufacture of cell wall polysaccharides (plant cells)Lysosomes- membrane vesicles that contain digestive enzymes (animal cells), secondary lysosomes digest food particles brought into cell (phagosomes), also digest old organellesFood particles brought in by phagocytosisFree vs. bound ribosomes- bound are found on the RER to package things out of the cell while free are located in the cytoplasm and help with producing proteins for the cellMitochondria-site of the chemical reactions of cellular respiration that supple cell with energy (ATP), have its own DNA)- Many foldsChloroplasts-site of chemical reactions of photosynthesis (have DNA)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Prokaryotic endosymbiosis? - Inner and outer membranes- Stacked membranes called thylakoids- Granum- stack of thylakoidsPlant Cells have unique organelles:- Vacuole- for storage-fluids, responsible for turgor pressure- Cell wall- made of sugars, gives rigidityCytoskeleton- supports and maintains cell shape, moves organelles in cytoplasm- Microfilaments- made of the protein actin, often interact with strands of other proteins- Intermediate filaments- anchoring cell structures- Microtubules- responsible for movement of organelles inside the cell, framework for motor proteins, made of protein tubulin- a dimer, polar, can change length my adding or subtracting dimerso One of main jobs- intercellular movement of DNA into 2 daughter cellso Can use their length and polarity for trafficking purposes, kinesins move towards the plus end to move cargo, kind of like little roadwayso Microtubules line cilia and flagella, 9 outer + 2 inner microtubules doublet arrangement, interactions with the motor protein dynein causes bending and movemento Microtubules bend cilia and flagellao Nextin can cross-link the doublets and prevent from slidingII. MembranesBoundaries- between cells and surrounding environmentWhich molecules can make it through the cell membrane? Nonpolar, hydrophobic small moleculesPhospholipids form a “fluid” bilayer-Occurs spontaneously in waterA variety of proteins “float” within the bilayerCarbohydrates attach to lipids or proteinsFluid mosaic model of Cell MembranesAll trans-membrane proteins are also integral membrane proteinsLipids composition- phospholipids vary in fatty acid chain lengthPercentage of cholesterol (up to 25%)Membrane composition can varyMembrane Proteins are (mostly) independent of the lipids-most lipids and proteins have weak hydrophobic interactionsLateral movement of membrane components occursPlasma membrane involved in cell adhesion and recognition3 types of Cell Junctions1. Tight junctions- prevents leaking between cells ex. Stomach Cells2. Gap Junctions- allow cell to cell communication, pores communicate with another cell3. Desmosomes- are like “spot
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