The main reason for the difference in the mass extinction occurring today and previously is the pace of the current extinction. The extinction is taking place globally and involves hundreds of species at the same time. In less than 50 years, we have lost numerous species. In contrast to this, previously during the mass extinction, only a few species were lost, and other managed to survive. But, not the status is opposite due to the magnitude of the extinction.
The four levels of protein structure are distinguished from one another by the degree of complexity in the polypeptide chain. A single protein molecule may contain one or more of the protein structure types: primary, secondary, tertiary, and quaternary structure. 1. Primary Structure: describes the unique order in which amino acids are linked together to form a protein.
2. Secondary Structure: refers to the coiling or folding of a polypeptide chain that gives the protein its 3-D shape. There are two types of secondary structures observed in proteins. One type is the alpha (α) helix structure. This structure resembles a coiled spring and is secured by hydrogen bonding in the polypeptide chain. The second type of secondary structure in proteins is the beta (β) pleated sheet. This structure appears to be folded or pleated and is held together by hydrogen bonding between polypeptide units of the folded chain that lie adjacent to one another
3. Tertiary Structure: refers to the comprehensive 3-D structure of the polypeptide chain of a protein.
4. Quaternary Structure: is the structure of a protein macromolecule formed by interactions between multiple polypeptide chains. Each polypeptide chain is referred to as a subunit. Proteins with quaternary structure may consist of more than one of the same type of protein subunit.
Answer: (Smallest = left) (Largest = right)
Individual = community = population = biome = biosphere = ecosystem
