Explain the antigen-antibody response
Show how a B cell makes an antibody that binds one specific antigen like a lock and key.
- Molecular shape determines binding: Antibody-antigen binding is shape-specific, so the idea that matching shapes fit together is needed first.
- Cells make proteins: An antibody is a protein a B cell produces, so knowing cells build proteins anchors where antibodies come from.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
An antigen is a molecular ID tag on an invader. A B cell makes an antibody, and that antibody binds one specific antigen like a lock and key.
The Y-shaped antibody has notched tips. Which statement is correct?
Reviewed- A.The antibody binds any antigen it touches
- B.The antibody binds only the antigen whose shape fits its notched tips
- C.The antibody is made by the skin
- D.The antibody and antigen are the same molecule
Show the worked solution ▾
Answer: B. The antibody binds only the antigen whose shape fits its notched tips
- Step 1: Read the shapes: The antibody's tips have a specific notch shape. Only a matching antigen fits; the differently shaped one does not.
- Step 2: Apply specificity: Because binding depends on matching shape, the antibody binds only its one matching antigen.
Why it's right: An antibody binds only the antigen whose shape matches its binding tips, like a key fitting one lock.
- A: An antibody is specific; it does not bind just anything it touches.
- C: Antibodies are made by B cells, not by the skin.
- D: An antigen (the invader's tag) and an antibody (the body's protein) are different molecules.
Aligned to HBS 3.2: antigen-antibody specificity · reading level ~grade 9
- A blood-typing test mixes known antibodies with a blood sample; clumping shows the matching antigen is present: antigen-antibody binding in action.
Fill these in as you work through the lesson.
- Antigen (the ID tag the immune system recognizes):
- Antibody (the protein that binds the tag):
- B cell (the cell that makes antibodies):
- Specific (one antibody, one antigen):
- Adaptive immunity (the line of defense this belongs to):
A B cell makes a protein called an . That protein binds to one specific on the invader, the way a key fits one lock.
- If an antibody is shaped to bind the flu antigen, will it also bind a measles antigen? Why or why not?
- Which cell makes antibodies, and which line of defense (innate or adaptive) is this?
- Explain why one antibody cannot defend against every possible invader.
A B cell makes an antibody shaped to bind antigen X on a specific bacterium. A different bacterium carries antigen Y. Explain whether this antibody will bind antigen Y, and what the body must do to handle antigen Y.