Muscle cells have the incredible ability to convert the chemical energy of adeno
ID: 3520342 • Letter: M
Question
Muscle cells have the incredible ability to convert the chemical energy of adenosine triphosphate (ATP) into the mechanical energy of muscle contraction.
There are three main events that need to take place to allow contraction of skeletal muscle fiber
Electrical excitation of a muscle fiber
Excitation-contraction coupling Muscle
fiber contraction due to the sliding filament mechanism Instructions:
Read and watch the following animation below to evaluate and interpret the process involved in the activation of the actin-myosin cross bridge (sliding filament mechanism) in skeletal muscle contraction.
Electrical Excitation of a Muscle Fiber Skeletal muscle fiber cells can be stimulated by a somatic motor neuron resulting in depolarization of the sarcolemma. If this depolarization reaches threshold, an action potential is initiated resulting in muscle contraction.
Describe a somatic motor neuron and how it communicates with a skeletal muscle cell?
Describe the process of depolarization within the sarcolemma and what is required for a stimulus to reach threshold, resulting in skeletal muscle contraction? Excitation-Contraction Coupling An action potential is transmitted along the sarcolemma and down the T tubules (transverse tubules).
This action causes calcium ions to be released from the terminal cisternae of the sarcoplasmic reticulum. Calcium ions couple electrical excitation to muscle fiber contraction by binding to troponin. Two events happen when calcium binds to troponin.
Describe these two events in great detail. Muscle Fiber Contraction due to the Sliding Filament Mechanism Watch the animated interaction between actin and myosin in the sliding filament mechanism during skeletal muscle contraction
.https://youtu.be/hgLSLJ09fZM
(Credit: Baneinaja, 2012) Estimated time to complete 20 seconds.
Evaluate and interpret the process in the actin-myosin cross bridge (sliding filament mechanism) during skeletal muscle contraction and answer the following questions below:
What happens to the position of the myosin head when ATP is hydrolyzed and ADP is attached to the myosin head group?
What event happens immediately after the myosin head binds to the active site on actin? Describe this process in great detail.
What happens to the position of the myosin head when ATP binds to the myosin head group?
Why does the actin filament only move in one direction?
Describe in great detail.Video: Muscle Contraction - Part 1Video:
Muscle Contraction - Part 2Video
: Muscle Contraction - Part 3
Explanation / Answer
1) When ATP is hydrolysed and ADP is attached to the myosin head group, the energy that is so released, causes the movement of the myosin head toward the actin filament.
2) Once the mysoin binds to the active site on the actin , it forms cross bridges. The myosin head actually tilts and pulls actin filaments so the slide on each other. Inside the sarcomere, the opposite ends of theactin myofilament move toward each other . This causes a MUSCLE CONTRACTION.
ATP is hydrolysed to ADP and phosphate and this releases the energy required for the contraction.
Because Actin is a POLAR molecule( it has positive or negative charge), the myosin can move along it in only one direction(depending on its polarity)
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.