Structure of Myofibrils Flashcards
What are the bundles that skeletal muscles are made of
Myofibrils
What are myofibrils made of
Sarcomeres
Describe sarcomeres
Unit of contraction
How many proteins are sarcomeres made out of
2
What are the 2 proteins that make up sarcomeres
Actin and Myosin
What is the appearance of a myofibril under an electron microscope?
Striped
Why does a myofibril look striped
They have alternating light and dark coloured bands
What are the 2 types of band in a myofibrils called
I and A bands
Describe the I bands
Lighter regions, where there are only thin actin filaments
Describe the A bands
Darker regions, where there are both actin and myosin filaments
What is in the middle of the A band
A lighter zone called the H zone which contains only myosin
What is in the middle of the I band
A line called the Z line
What is between 2 Z lines
1 sarcomere
