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Across 3. The male reproductive cell. 5. Antibodies produced by injecting animals with a specific antigen. A series of antobodies are produced responding to a variety of different sites on the antigen. 7. A red blood cell. 9. A protein in the blood serum that destroys or inactivates a specific antigen. 10. Fused spleen and tumor cells. Used to produce identical monoclonal antibodies in a limitless supply. 11. Having two identical allelic genes on two corresponding positions of a pair of chromosomes. 12. The male sex chromosome. 14. A collection of identical antibodies that interact with a single antigen site. 17. An antibody that reacts with its corresponding antigen to form a precipitate. 22. The basic unit of heredity, consisting of a DNA segment located on a chromosome. 23. A substance, usually a protein, that stimulates the body to produce antibodies against it. 25. A threadlike structure in the cell nucleus, along which the genes are located. 28. Any of several alternative forms of a gene located at the same point on a particular pair of chromosomes. 29. The clumping together of red blood cells by the action of an antibody. 30. Blood serum that contains specific antibodies. 31. The female reproductive cell. 32. The fluid portion of unclotted blood.

Down 1. The molecules that carry the body’s genetic information. 2. An enzyme found in high concentration in semen. 4. The physical manifestation of a genetic trait such as shape, color, or blood type. 6. The liquid that separates from the blood when a clot is formed. 8. The female sex chromosome. 13. The study of antigen–antibody reactions. 15. An abnormally low sperm count. 16. The most sensitive chemical test that is capable of presumptively detecting bloodstains diluted up to 300,000 times. Its reaction with blood emits light and thus requires the result to be observed in a darkened area. 18. Having two different allelic genes on two corresponding positions of a pair of chromosomes. 19. A red blood cell protein that transports oxygen in the bloodstream; it is responsible for the red color of blood. 20. The particular combination of genes present in the cells of an individual. 21. The physical location of a gene on a chromosome. 24. A protein that acts as a catalyst for certain specific reactions. 26. The absence of sperm; sterility in males. 27. The cell arising from the union of an egg and a sperm cell.