Titin , also known as connectin, is a protein that, in humans, is encoded by the TTN gene. Titin is a giant protein, greater than 1 µm in length, that functions as a molecular spring which is responsible for the passive elasticity of muscle. It is composed of 244 individually folded protein domains connected by unstructured peptide sequences. These domains unfold when the protein is stretched and refold when the tension is removed.Titin is important in the contraction of striated muscle tissues. It connects the Z line to the M line in the sarcomere. The protein contributes to force transmission...

A gamete (; from Ancient Greek γαμετή gamete from gamein "to marry") is a haploid cell that fuses with another haploid cell during fertilization (conception) in organisms that sexually reproduce. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a female is any individual that produces the larger type of gamete—called an ovum (or egg)—and a male produces the smaller tadpole-like type—called a sperm. In short a gamete is an egg (female gamete) or a sperm (male gamete). This is an example of anisogamy or heterogamy, th...