Grade 11Botany

In muscle, the functional unit of contraction, which is a portion of a myofibril, positioned in between two successive Z lines is?
A
I band
B
A band
C
H zone
D
I band with Z line

ravish kumar

5 Years agoGrade 11

5 Years ago

Myofibril is made of two types of filaments. They are thin filament(actin ) and thick filament(myosin).
Each myofibril has alternate dark and light bands on it. The light bands contain actin and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin.
In the centre of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it. The thin filaments are firmly attached to the ‘Z’ line.
The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere.
Hence In muscle, the functional unit of contraction, which is a portion of a myofibril, positioned in between two successive Z lines is I band.
So, the correct answer is I band'.