Antibodies Lock Onto a Virus

In the picture

1. 1A virus particle: the foreign body carrying surface proteins
2. 2An antigen fragment on a dendritic cell: a piece of the pathogen shown on the cell surface
3. 3A B-cell receptor on a lymphocyte: a Y-shaped receptor that fits one antigen shape
4. 4An antibody clamped to a virus spike: a Y-shaped protein bound to its matching antigen

Examples

• A tetanus booster makes antibodies that stick to the tetanus toxin before it reaches the nerves.
• A rapid throat swab test uses antibodies to catch bacterial proteins from the sample.

Quiz: Antibodies Lock Onto a Virus (Age 18)

1. 1

   In this immune response, which B lymphocyte is activated?

   • The one that already has the most antibodies attached to its surface.
   • The one whose receptor matches an antigen fragment displayed by a dendritic cell.
   • The one that happens to encounter the virus first, whatever its receptor shape.
2. 2

   What is the main effect of antibodies binding to a virus?

   • They cut the pathogen into fragments so a dendritic cell can display them.
   • They turn the virus into a B lymphocyte that makes more receptors.
   • They mark the pathogen so other immune cells can destroy it.
3. 3

   How does the dendritic cell help start the specific B-cell response?

   • It injects its own B-cell receptors into the virus.
   • It releases antibodies that clamp onto the virus spikes.
   • It cuts the pathogen apart and displays antigen fragments on its surface.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.