Match the following images with the respective given steps P,Q,R,S:
P. Macrophage receptors recognise the invading virus.
Q. The virus is drawn into the macrophage.
R. The virus get packaged into a sac pinched off from the cell membrane of the macrophage.
S. The sac fuses with lysozyme which safely dismantles the bacterium without digesting the macrophage itself.
I - P, II - R, III - Q, IV - S
To a macrophage, anything foreign is there to be eaten. When bacteria or viruses enter the body and find their way into the tissue, they leave a chemical trail that is detected by receptors on a patrolling macrophage's cell membrane. If receptors on these extensions recognise specific markers on the bacterial or viral surface, they bind to them. Once captured, the virus or bacterium is drawn into the macrophage and packaged in a sac pinched off from the cell membrane. As it moves through the cytoplasm, the sac fuses with lysozyme. These safely dismantle the bacterium without digesting the macrophage itself.