Answer:
In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.
Explanation:
The correct answer is false. Extinction of organisms is not solely cause by man. Even way before, extinction is already happening. It can be caused by natural or human causes. Natural causes includes volcanic eruptions, earthquakes, floods, etc.
I remember the secondary structure by visualizing it. Understand that primary structure is just the order of the amino acids. The tertiary structure is the 3dimensional configuration of the whole protein molecule with multiple interactions guiding its fold (disulfide bonds, ionic interactions, hydrogen bonds, van der walls). Secondary structure is a step towards the conformation of the protein where it is made up of either alpha-helices or beta-pleated sheets. The alpha helices look like a spiraling staircase while the beta-pleated sheets look like a repetition of long loops. These two structures hold itself by hydrogen bonds.
