AP BIOLOGY

Detailed explanation-1: -Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Detailed explanation-2: -DNA stores biological information in sequences of four bases of nucleic acid-adenine (A), thymine (T), cytosine (C) and guanine (G)-which are strung along ribbons of sugar-phosphate molecules in the shape of a double helix.

Detailed explanation-3: -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.

Detailed explanation-4: -By housing the cell’s genome, the nucleus serves both as the repository of genetic information and as the cell’s control center. DNA replication, transcription, and RNA processing all take place within the nucleus, with only the final stage of gene expression (translation) localized to the cytoplasm.

Detailed explanation-5: -DNA is tightly packed up to fit in the nucleus of every cell. As shown in the animation, a DNA molecule wraps around histone proteins to form tight loops called nucleosomes. These nucleosomes coil and stack together to form fibers called chromatin.