Myofibrils

• What do myofibrils contain?


  Bundles of thick and thin myofilaments that move past each other to make muscles contract
• What are thick myofilaments made of?


  the protein myosin
• What are thin myofilaments made of?


  the protein actin
• What will you see if u look at a myofibril under an electron microscope?


  a pattern of alternating dark and light bands
• What do dark bands contain?


  the thick myosin filaments and some overlapping thin actin filaments - these are called A-BANDS
• What do light bands contain?


  Thin actin filaments only - these are called I-BANDS
• What is a myofibril made up of?


  Many short units called SARCOMERES
• wHat are the ends of each sarcomere marked with?


  A Z-line
• WHat is in the middle of each sarcomere?


  An M-Line
• What is the M-line?


  The Middle of the Myosin filaments
• What is around the M-LINE?


  The H-zone
• What does the H-Zone contain?


  ONLY contains myosin filament