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.
What is Rigor Mortis?
Interactive Physiology Muscle
Contraction
• http://www.interactivephysiology.com/ip10/
muscular/slidflmt/topic28.html
Sequential Events of Contraction – Cross Bridge Cycle
Myosin head
(high-energy
configuration)
3
Actin Filament
ADP and Pi (inorganic
phosphate) released
Myosin
Filament
2
4
Myosin head
(low-energy
configuration)
1
Adapted from ©Pearson 2013 Elaine N. Marieb et al Human Anatomy and Physiolgy 9th Ed.
Sequential Events of Contraction – Cross Bridge Cycle
Myosin head
(high-energy
configuration)
3
Myosin head attaches to the actin
myofilament
Actin filament
Myosin
filament
2
4
Cocking of the myosin head
occurs
Power stroke—the myosin head pivots and
bends as it pulls on the actin filament
Myosin head
(low-energy
configuration)
1
The myosin head detaches
the cross bridge is lost
Figure 9.11
Clicker Question :
Myosin head
(high-energy
configuration)
3
Myosin head attaches to the actin
myofilament
Actin filament
Myosin
filament
2
4
Cocking of the myosin head
occurs
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.
Power stroke—the myosin head pivots and
bends as it pulls on the actin filament
Myosin head
(low-energy
configuration)
1
The myosin head detaches
the cross bridge is lost
Figure 9.11
Sequential Events of Contraction – Cross Bridge Cycle
Myosin head
(high-energy
configuration)
3
Myosin cross bridge attaches to
the actin myofilament
Actin filament
ADP and Pi (inorganic
phosphate) released
Myosin
filament
2
As ATP is split into ADP and Pi,
cocking of the myosin head occurs
4
Power stroke—the myosin head pivots and
bends as it pulls on the actin filament, sliding it
toward the M line
Myosin head
(low-energy
configuration)
1
As new ATP attaches to the myosin
head, the cross bridge detaches
Figure 9.11
Clicker Question
In rigor mortis, predict the stage where this cycle
would stop?
B
C
A
D
Defend your answer to your
neighbor.
B
C
A
D
Clicker Question
In rigor mortis, predict the stage where this cycle
would stop?
B
C
A
D
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.
Alignment – Group 6 – Move Me
Learning Objective
Assessment
Active learning
Low Order/
High Order
Know how ATP
binding and hydrolysis
regulate the
interaction of actin
and myosin
Formative:
Strip sequence
Summative: Exam
Question - Predict would
happen in the absence of
ATP and justify your
answer
Strip sequence and placement
of ATP and ADP
Formative
Part 1
Recall – Low
Dramatization of the actin
myosin movement
Part 2
Predict – High
Summative
Predict – High
Know the physical
movement of the
myosin and how it
functions as a motor.
Formative:
Dramatization of the
actin myosin movement
Summative:
Exam question - Predict
properties of various
myosin dysfunction s ie.
Mutated ATP binding site
Diversity
All students participate in the activity. There is a diversity of learning styles: visual, auditory, and
kinesthetic.