AP BIOLOGY

Detailed explanation-1: -Double helix, as related to genomics, is a term used to describe the physical structure of DNA. A DNA molecule is made up of two linked strands that wind around each other to resemble a twisted ladder in a helix-like shape. Each strand has a backbone made of alternating sugar (deoxyribose) and phosphate groups.

Detailed explanation-2: -To avoid bumping into each other, the staircase has to twist a little bit. This turns our staircase into a spiral staircase. This extra twist at the end is the reason for the helical shape. For the “steps” of the DNA “staircase” to fit together, they have to twist a little bit, making the final spiral shape of DNA.

Detailed explanation-3: -As per the Watson-Crick double helical model, DNA is composed of two complementary polynucleotide chains which are anti-parallel to each other. Both the strands of DNA are held together by Hydrogen bonds and coiled around a common axis.

Detailed explanation-4: -These nucleosomes coil and stack together to form fibers called chromatin. Chromatin, in turn, loops and folds with the help of additional proteins to form chromosomes. Condensing DNA into chromosomes prevents DNA tangling and damage during cell division.

Detailed explanation-5: -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.