Question

Given above is the diagram of a bacteriophage. In which one of the options all the four parts A, B, C and D are correct?

	A	B	C	D
1	Collar	Tail fibres	Head	Sheath
2	Tail fibres	Head	Sheath	Collar
3	Sheath	Collar	Head	Tail fibres
4	Head	Sheath	Collar	Tail fibres

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (D)

4

The genetic material of the bacteriophage is stored in the head or capsid region. The main function of the capsid is to protect the genetic material from the environment. Specifically, the capsid prevents enzymes from breaking down the genetic material. From the capsid, a long string of proteins makes up the tail structure of a bacteriophage. The tail is a hollow tube that serves as a passageway for the genetic material to pass from the capsid to the host bacteria. The neck is decorated by the collar and whiskers, made of fibritin molecules. The collar and whiskers are environment-sensing devices, regulating the retraction of the long tail fibers under unfavorable conditions, thus preventing infection. The entire tail is covered with a sheath, and some bacteriophages feature a base plate and fibers at the bottom of the tail. The base plate and fibers are used to securely attach the bacteriophage to the bacteria sheath, which contracts during an infection.