Answer:
tertiary; quaternary
Explanation:
The orientation of all the atoms of a protein in three dimensions represents its tertiary structure. It includes the folding of the polypeptide chains in a way that brings are far apart amino acids of its secondary structure close together. Various segments of a polypeptide chain interact to form tertiary structures and these segments are held together by different kinds of weak interactions.
However, disulfide cross-links between the segments of polypeptide chains also stabilize the tertiary structure of some proteins. Likewise, disulfide bonds also hold the protein subunits of some proteins together and thereby, contribute to the quaternary structure. For example, two light chains of an antibody are joined together by disulfide bonds.
Answer: One of the ways that people of ancient times classified plants and animals is by use. Today, group the creatures, as they do the plants, on the premise of shared physical attributes. They put them in a progressive system of groupings, starting with the kingdom Animalia and continuing through phyla, classes, orders, families, genera and species.
Explanation:
Adjustment knobs are used to focus light in a light microscope
