DNA model Nitrogenous bases pair to form the rungs of the ladder Alternate sugar-phosphate form the poles of the ladder Cytosine - one of the 4 types of nitrogenous bases Thymine - one of the 4 types of nitrogenous bases Guanine - one of the 4 types of nitrogenous bases Adenine - one of the 4 types of nitrogenous bases Hydrogen bonds - keep the two nucleotide chains together Phosphate group Deoxyribose sugar

DNA location Cytoplasm Nucleus - contains most the DNA Plasma membrane