Move Me Mountain West Summer Institute 2013 David Aguilar, University of California San Diego Lisa Gallegos, Otero Junior College Richard Gomer, Texas A&M University Warren McClure, Otero Junior College Kathryn Ryan, Texas A&M University

Unit Goal – Understand how motor proteins interact with cytoskeleton components to direct movement. Context – General Biology or Human Anatomy & Physiology – Freshman/Sophomore – Tidbit will be in the middle of a 1-2 week unit. Tidbit may be followed by discussion of neutrophil movement and/or cytokinesis. Next class will cover other molecular motors. Prior Knowledge – Three main types of cytoskeletal proteins – ATP as an energy source – Components and arrangement of sarcomeres in skeletal muscle – Introduction to the Sliding Filament Theory

Tidbit Goal Know how ATP binding and hydrolysis regulate the interaction of actin and myosin Teachable tidbit intended learning outcomes – Describe the molecular structure and functional features of a myosin molecule. – Dramatize the interaction of myosin and actin during the ATP cycle. – Discuss how the physical features of myosin allow it to function as a motor protein. – Recall ATP hydrolysis causes the high energy configuration of the myosin head. – Explain how actin and myosin interact to contract a muscle. – Predict what happens if there is no ATP.

Tidbit Activity Students will engage in a group activity to complete a strip sequence and dramatize the interactions of actin, myosin, and the ATP cycle in a muscle contraction.

What is Rigor Mortis?

Interactive Physiology Muscle Contraction muscular/slidflmt/topic28.html muscular/slidflmt/topic28.html

Myosin head (high-energy configuration) Myosin Filament Myosin head (low-energy configuration) ADP and P i (inorganic phosphate) released Sequential Events of Contraction – Cross Bridge Cycle Figure 9.11 Actin Filament

1 2 4 Myosin head (high-energy configuration) Myosin Filament Myosin head (low-energy configuration) ADP and P i (inorganic phosphate) released Sequential Events of Contraction – Cross Bridge Cycle Adapted from ©Pearson 2013 Elaine N. Marieb et al Human Anatomy and Physiolgy 9 th Ed. Actin Filament 3

Myosin head attaches to the actin myofilament Power stroke—the myosin head pivots and bends as it pulls on the actin filament The myosin head detaches the cross bridge is lost Cocking of the myosin head occurs Myosin head (high-energy configuration) Myosin filament Myosin head (low-energy configuration) Sequential Events of Contraction – Cross Bridge Cycle Figure 9.11 Actin filament

Myosin head attaches to the actin myofilament Power stroke—the myosin head pivots and bends as it pulls on the actin filament The myosin head detaches the cross bridge is lost Cocking of the myosin head occurs Myosin head (high-energy configuration) Myosin filament Myosin head (low-energy configuration) Where would you predict ATP is interacting with myosin in this cycle? A. Position 1 B. Position 2 C. Position 3 D. Position 4 E. Multiple locations. Figure 9.11 Actin filament Clicker Question :

Myosin cross bridge attaches to the actin myofilament Power stroke—the myosin head pivots and bends as it pulls on the actin filament, sliding it toward the M line As new ATP attaches to the myosin head, the cross bridge detaches As ATP is split into ADP and P i, cocking of the myosin head occurs Myosin head (high-energy configuration) Myosin filament Myosin head (low-energy configuration) ADP and P i (inorganic phosphate) released Sequential Events of Contraction – Cross Bridge Cycle Figure 9.11 Actin filament

Clicker Question In rigor mortis, predict the stage where this cycle would stop? A D C B

Defend your answer to your neighbor. A D C B

Clicker Question In rigor mortis, predict the stage where this cycle would stop? A D C B

Summative Questions – What is the consequence of taking cyanide which disrupts cell respiration? Explain in terms of molecular motors. – Sketch or arrange the interaction of myosin and actin during the ATP cycle.

Learning Objective AssessmentActive learning Low Order/ High Order Know how ATP binding and hydrolysis regulate the interaction of actin and myosin Know the physical movement of the myosin and how it functions as a motor. Formative: Strip sequence Summative: Exam Question - Predict would happen in the absence of ATP and justify your answer Formative: Dramatization of the actin myosin movement Summative: Exam question - Predict properties of various myosin dysfunction s ie. Mutated ATP binding site Strip sequence and placement of ATP and ADP Dramatization of the actin myosin movement Formative Part 1 Recall – Low Part 2 Predict – High Summative Predict – High Diversity All students participate in the activity. There is a diversity of learning styles: visual, auditory, and kinesthetic. Alignment – Group 6 – Move Me