DMD Lesson Activity

DMD and Muscle Structure

Genetics Lesson

​Study the diagram. Look at the relationship between a muscle-fascicle-muscle fiber-myofibril-sarcomere.

​Muscle Anatomy

Open Ended

In the space below, describe the relationship between muscles, fascicles, muscle fibers, and myofibrils and sarcomeres:

There are three types of muscle found in the human body: smooth, cardiac and skeletal. Smooth muscles are responsible for involuntary movements of body tissues like digestion or contraction of blood vessels. Cardiac muscles are responsible for the contraction of your heart. Skeletal muscles are responsible for the voluntary movements of the body (lifting, walking, running etc.)  

Muscles are made of lots of long muscle cells. A muscle cell contains myofibrils which contain sarcomeres. Within a sarcomere are many different types of proteins. Actin and myosin are two of these proteins that are responsible for muscle contractions. They are categorized as contractile proteins. Muscle fibers also contain structural proteins such as titin and dystrophin. 

The sizes of muscles can change for a variety of reasons. When a person uses their muscles, some of the fibers tear. When muscle fibers are repaired, they are typically larger in size than they were before. This is how a person can increase their muscle size through exercise. Hypertrophy is a term for an increase in muscle size. On the other hand, when muscles are not used regularly, they can decrease in size. Atrophy is a term for a decrease in muscle size due to lack of use. Finally, dystrophy is a term for muscle decrease. When people with Duchenne’s Muscular Dystrophy exercise, their muscles do not get repaired or grow, and they break down and decrease in size over time.

Open Ended

Do a little research.....Document the function of the following: actin, myosin, titin, dystrophin.

Multiple Choice

The muscles in the human body that are connected to bones and aid in the movement of the ______________ are called skeletal muscles.

• body

• skeleton

• muscles

Multiple Choice

These muscles are connected to bones by ________________.

• tendons

• ligaments

• I-band

• A-band

Multiple Choice

Within each of the skeletal muscles are bundles of muscle fibers. These bundles are also called ___________________. 

• fascicles

• myofibrils

• sarcomere

• sarcolemma

Multiple Choice

Each skeletal muscle fiber contains many ________________, which are rod-shaped and contains many sarcomeres (the functioning unit of muscle tissue.) 

• myofibrils

• sarcolemma

• muscle fibers

• sarcoplasm

Multiple Choice

Sarcomeres are made up of thin filaments (composed mainly of the protein _____________) and thick filaments (composed mainly of the protein ______________.)

• actin, myosin

• titin, dystrophin

• myosin, actin

• dystrophin, titin

Multiple Choice

The actin of the outermost myofibril is connected to the cell membrane by a protein called ________________.

• titin

• dystrophin

• myosin

• actin

Open Ended

What is the role of creatine kinase in the myofibril?

Open Ended

What happens in the muscle cells of individuals with DMD? (Be specific, mention dystrophin protein, creatine kinase, calcium ions, etc.)

Do some research....

Use google to complete the research.

Duchenne's muscle dystrophy is an X-linked recessive disorder. What does it mean for a disorder to be X-linked?
What does it mean for a disorder to be recessive?

Open Ended

Explain how Duchenne's Muscular Dystrophy is inherited and what this disorder does to those who inherits the disorder at the cellular level.