Protein or the physical region of the protein that participates in chemical catalysis. In solution proteins also undergo variation in structure through thermal vibration and the collision with other molecules. Proteins can be informally divided into three main classes, which correlate with typical tertiary structures: globular proteins, fibrous proteins, and membrane proteins. Almost all globular proteins are soluble and many are enzymes. Fibrous proteins are often structural, such as collagen, the major component of connective tissue, or keratin, the protein component of hair and nails. Membrane proteins often serve as receptors or provide channels for polar or charged molecules to pass
Pubic hair be regarded as unaesthetic or embarrassing and is therefore trimmed or otherwise styled to avoid it being visible. Pubic hair forms in response to the increasing levels of testosterone in both girls and boys. Those hair follicles are located and stimulated in androgen sensitive areas develop pubic hair. The Tanner scale describes and quantifies the development of pubic hair. Before the onset of puberty, the genital area of both boys and girls has very fine vellus hair (stage 1). At the onset of puberty, the body produces rising levels of the sex hormones, and in response, the skin of the