<em>Muscle cells are excitable, meaning they react to stimuli. They may shorten and create a pulling force because they are contractile. Locomotion, facial expressions, posture, and other voluntary motions of the body are all made possible by the contraction of skeletal muscle, which is connected to bones.</em>
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<em>Also, Taylor Swift*</em>
Hairs are mostly fibrous proteins and are composed of keratin, and also the main constituent of skin, nails, wool, woof, feathers etc.
Keratin is the essential fibrous protein which has a structural and protective functions in the epithelium.
Answer:
Polypeptide
Explanation:
Amino acids are the building block and simplest unit of protein molecules. The structural composition of each amino acids is made up of an amine group (-NH2), a carboxylic acid group (-COOH), a hydrogen atom (H) and a R side chain that differentiates every amino acid from one another.
In a reaction process called condensation, amino acids are chemically joined together via the amine group of one and the carboxylic group of another. This process releases water molecule (H20) to form a bond called PEPTIDE bond between the amino acids. Several amino acids in their 100’s or 1000’s that are chemically joined this way forms a POLYPEPTIDE chain, which in turn forms the protein molecule.
