... key areas of science: Life, Earth, and Physical. However, the Big Ideas show that there are no real boundaries in knowledge, and that by understanding a big idea in one area of science you can ... DNA The shape of a DNA strand is like a spiraling ladder. Look at the model above. Along the sides, you can see the chain of sugar and phosphate molecules that make up the backbone of the ... you realize that a fish is related to a banana tree? In fact, all living things on Earth—people, zebras, yeast, and plants—are related and share a fundamental structure of life: DNA. DNA, short...