Sperm cell. Computer artwork of a human sperm cell, showing its inner structure. The sperm head (orange) carries genetic material, which combines with genetic material carried by an egg during fertilisation. The head is capped by the acrosome (pale blue), an organelle containing the enzymes for dissolving the egg's tough outer coating before entering and fertilising it. The central section (yellow) contains mitochondria, which provide energy for the tail, which beats to propel the sperm. The blue double helix strands around the tail represent a molecule of DNA.