When molecules are insoluble (unable to be dissolved), they clump together and become visible. DNA is not soluble in alcohol; therefore, it makes the DNA strands clump together and become visible to the naked eye.
Besides, can you see chromosomes under a microscope?
During most of the cell cycle, interphase, the chromosomes are somewhat less condensed and are not visible as individual objects under the light microscope. However during cell division, mitosis, the chromosomes become highly condensed and are then visible as dark distinct bodies within the nuclei of cells.
Why can you see the DNA of a strawberry?
Ripe strawberries are an excellent source for extracting DNA because they are easy to pulverize and contain enzymes called pectinases and cellulases that help to break down cell walls. And most important, strawberries have eight copies of each chromosome (they are octoploid), so there is a lot of DNA to isolate.
How do we know what DNA looks like?
DNA looks like an incredibly long twisted ladder. This shape is called a double helix. The sides of the ladder are a linked chain of alternating sugar and phosphate molecules. The rungs connect to the sugar molecules and are known as bases.