Protein structure is the three-dimensional arrangement of atoms in a protein molecule. Proteins are polymers — specifically polypeptides — formed from sequences of amino acids, the monomers of the polymer. A single amino acid monomer may also be called a residue (chemistry) indicating a repeating unit of a polymer. Proteins form by amino acids undergoing condensation reactions, in which the amino acids lose one water molecule per reaction in order to attach to one another with a peptide bond. By convention, a chain under 30 amino acids is often identified as a peptide, rather than a protein.[1] To be able to perform their biological function, proteins fold into one or more specific spatial conformations driven by a number of non-covalent interactions such as hydrogen bonding, ionic interactions, Van der Waals forces, and hydrophobic packing. To understand the functions of proteins at a molecular level, it is often necessary to determine their three-dimensional structure. This is the topic of the scientific field of structural biology, which employs techniques such as X-ray crystallography, NMR spectroscopy, and dual polarisation interferometry to determine the structure of proteins.
Protein structures range in size from tens to several thousand amino acids.[2] By physical size, proteins are classified as nanoparticles, between 1–100 nm. Very large aggregates can be formed from protein subunits. For example, many thousands of actin molecules assemble into a microfilament.
A protein may undergo reversible structural changes in performing its biological function. The alternative structures of the same protein are referred to as different conformational isomers, or simply, conformations, and transitions between them are called conformational changes.
smell, the taste is 80% smell... smell picked up by olfactory receptor cells.
Answer:
flagella
Explanation:
Some bacteria have tail-like structures called flagella
Answer:
Pseudopodia are temporary and cytoplasm-filled parts of the cell membrane that are able to change their form in order to move.
Explanation:
Pseudopodia are temporary and cytoplasm-filled parts of the cell membrane that are able to change their form in order to move. They are used in some eukaryotic cells to move around or to eat. Most cells that do this are called amoeboids. The amoeba is a common example. ... Pseudopods can also capture prey by phagocytosis.
