AP BIOLOGY

Detailed explanation-1: -The model is called a double helix because two long strands twist around each other like a twisted ladder. The rails of the ladder are made of alternating sugar and phosphate molecules. The steps of the ladder are made of two bases joined together with either two or three weak hydrogen bonds.

Detailed explanation-2: -Suggested Materials: dry macaroni, string, pipe cleaners, wire coat hangers, beads, white glue, cardboard, styrofoam peanuts, toothpicks. Materials to avoid: anything that will mold, mildew, rot, melt, etc. such as marshmallows or gumdrops.

Detailed explanation-3: -Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.

Detailed explanation-4: -The discovery of the structure of DNA in 1953 was made possible by Dr Rosalind Franklin’s X-ray diffraction work at King’s.

Detailed explanation-5: -Nucleotides are the units which, when linked sugar to phosphate, make up one side of a DNA ladder.