Bio 201 1st Edition Lecture 11Outline of Last Lecture I. Peroxisomes and GlyoxysomesII. CytoskeletonA. 3 TypesB. Determining Molecular SizeOutline of Current Lecture I. Muscle ContractionA. MyosinII. TransportA. KinesinB. DyneinCurrent LectureI. Cell Contraction- Scientists knew that muscles contracted when ATP was exposed toa certain protein. To find out what protein it was they had an approach: 1. Purify proteins that bind to actin 2. Glue proteins to surface of glass slide and add fluorescent actin capped at both ends to prevent polymerization and depolymerization 3. Add ATP. After doing this they found the protein was Myosin. Muscle contraction structure contains A-band- dark patch in middle, H-zone- center of A-band, comprised of thick filaments, Z-line- outer line, and I-band-transparent bond in between Z-line and A-band. A. Myosin- Protein that drags actin filament along so that the plus end is closest to the myosin. This is a plus end-directed actin motor protein. -Myosin is a large and complex protein. Composed of a head and atail. The myosin tail is what anchors the myosin network, while the head does most of the work, binding to Actin and ATP and catalyzing ATP hydrolysis. -Myosin contraction cycle; Tail anchors to filament, head binds to actin and contracts pushing the actin 10nm then the myosin releases from actin andrebinds, starting the process over again. -ATP is needed to release myosin from the actin filament. 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.This is why rigor mortis (stiffness) happens when a person dies, because ATP is not produced which cause myosin to stay attached and the muscles continuously contract. II. Transport- Migration occurs along microtubules. Can happen in a forward or reversedirection. -Anterograde- away from cell body/ nucleus-Retrograde- towards cell body/ nucleusA. Kinesin- looks like myosin, has tail that anchors and head that does most of the work. -Plus end microtubule motor, ATP is also required for release. -Anterograde reaction because kinesin goes towards the plus end. B. Dynein- Negative end microtubule. Head binds to microtubule/ ATP and catalyzes ATP hydrolysis. Tail anchors to cargo. ATP is required for release. -Retrograde reaction because Dynein goes towards negative end. -Axonomeal dynein is the motor protein of cilia and flagella. Cilia is comprised of microtubules and moves by a double headed dynein, which forms bridges between
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