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Name: _____________________________ Period: ____________ Infective Cycles of Viruses Textbook reference: L2 Biology section 16.5, L3 Biology section 19-3. Viruses are particles that enter living cells and use the cell’s machinery to produce more virus particles. Some viruses destroy the host cell immediately after they infect it. Others incorporate their genetic material into the host and may remain inactive for several generations. Study the two different infective cycles of viruses illustrated below, then complete the following paragraph using your text to assist. A C D B The unshaded portion of the diagram shows a _______________________ cycle. It begins when a specific type of virus called a (A) _____________________________ attaches to a (B) _______________________. The tail of A releases an ______________________ that breaks down the cell surface of B. The outer portion of the tail of A contracts and the (C) _____________________________________ is injected into B. Inside the cell, C takes over. The cell B is directed to make copies of C and of the viral protein coat called a _______________________. The protein coat and C are then assembled into ________________________ _____________________________. Before long the cell C bursts open in a process called ______________ and hundreds of new viral particles are released. The shaded portion of the diagram represents a ____________________________ cycle. This cycle differs from the previous cycle in that it includes the process by which (D) _______________________________ becomes part of the DNA of B. When B copies its own DNA during replication, the __________________ is also _______________________________. This process can be repeated for ______________________ ______________________________. Eventually some factor will trigger a change in the cell and the D will exit the host DNA and enter the _________________________ cycle, resulting in the release of new _________________________________________________.