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BU BIOL 118 - lecture 150209

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Chapter Seven- Cell components structure and functionProkaryotic-- Lack of membrane bound organelles - DNA just floating around in cytoplasm- Bacteria and archea- Usually single celled organismsEukaryotic- Membrane bound organelles- DNA contained in a nucleus- Large multicellular organisms are commonPancreatic cella. Animal cell; no cell wallb. Make enzymes and secrete them into the small intestine for digestionc. Lots of rough ER for making proteins (rough ER contains ribosomes for making transmembrane proteins or proteins that have a significant polar part and a significant non-polar part)d. Lots of vesicles for transporting proteins out of cellAnimal testis cella. Lots of smooth ER for making lipids such as testosteroneb. Exports lipid soluble signalsPlant leaf cella. Make atp and sugarsb. Lots of chloroplasts for energyc. Cell shape is very rigid due to vacuole and cell walld. Tobacco leaf vacuoles store nicotineBrown fat cella. Lots of mitochondriab. In hibeRNAting animals and babiesc. Specialized mitochondria produce heat rather than atpThe point of these was to show that STRUCTURE = FUNCTIONCell systems 1. Nuclear transporta. Things must go through the nuclear envelope to get into the nucleusb. Envelope has two layers: inner and outer membranec. Also a nuclear pore complexd. Things going in: DNA and RNA materialsi. All things going in need a nuclear localization signal (NLS) to let them in, 17 amino acid long tag, sometimes call molecular zip codeii. Some viruses like AIDS have evolved to have their own NLS even though that’s bad for the hoste. Things going out: RNA2. Endomembrane systema. Made of smooth and rough ER and Golgi apparatusb. Protein and lipid production (ER)c. Transportation of proteins and lipids (Golgi)d. Golgi apparatus has a cis side and a trans sidei. Cis side- closest to ERii. Trans side- closest to cell membraneiii. Receives proteins/lipids from vesicles from ERe. Protein transportation is very tightly regulated by secretory pathway -> ER to Golgi to vesicle to cell membrane (or where ever)f. Proteins need a way to get into the endomembrane system SIGNAL HYPOTHESISPULSE CHASE EXPERIMENT: used to support secretory pathway model- Find some normal cells- label proteins with a radioactive amino acids so their movement can be followed- Add radioactive amino acids to the cells- Track amino acids- Record their locationso Seems like they went from ER to Golgi to secretory vesiclesThe Signal Hypothesis- Proteins bound for the endomembrane system have a code the directs polypeptides to the ER proteins come to the ER mid-production so they are partially made and then have to go to the ER- 20 amino acids long- Sequence binds to a signal recognition particle (SRP) that then binds to a receptor in the ER membrane- the signal sequence gets removed once the protein arrives at the ER- In the rough ER lumen protein production happens and the tag tells where the protein should go and whatnot- Inside ER glycosylation adds carbohydrates to proteins - Then proteins go to vesicles which take them to where ever they need to goEndocytosis- breaking down proteins and recycling the bits for new proteins3. Dynamic cytoskeleton- made of Actin intermediate filaments and microtubulesa. Actin and myosin allow movement to occurb. Cytokinesis in animals- animal cells splitting in two during mitosis/meiosisc. Actin myosin interactions- cytoplasmic


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