 Reproduction (1 of 6) Egg, sperm, and zygote Eggs and sperm carry only half the usual number of chromosomes — just 23 unpaired chromosomes, carrying one version of each gene. When the egg and sperm get together, the baby receives the normal 23 matched pairs.
 |  |  Reproduction (2 of 6) Chromosome duplication When eggs and sperm are produced, the parent cell first copies each chromosome, leaving the duplicate pairs attached to one another.
 |  |  Reproduction (6 of 6) Zygote with recombinant genes When egg and sperm meet, the baby inherits a combination of genes that is totally unique: it carries versions of genes from all 4 grandparents plus any mutations that occurred when the mother and father were making the egg and sperm.
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