2 DNA Structure and Function KEY CONCEPTSVOCABULARYWho helped discover DNA?What does DNA do for us?What is the structure of DNA?What is DNA made of?DNAAdenineGuanineCytosineThyminePurinesPyrimidinesNucleotide
3 DNA DNA stands for deoxyribonucleic acid Large molecule that contains all genetic informationFunctions of DNA:Directs the activities of cellsContains the instructions cells use to make proteinsWhat kinds of things do living organisms use proteins for?
4 HistoryRosalind Franklin took the first x-ray pictures of DNA moleculesThe x-ray pictures helped scientists to determine the shape of DNA.What is the shape of a DNA molecule?
5 History James Watson and Francis Crick built the first DNA model They are given credit for first determining the double helix shape
6 Structure A strand of DNA is made of monomers called nucleotides Each nucleotide has three parts:Sugar (deoxyribose)PhosphateNitrogen baseThe nitrogen base always binds to the sugar of a nucleotide
7 Structure There are four different DNA nitrogen bases: AdenineGuanineCytosineThymineAdenine and guanine are single-ringed purinesCytosine and thymine are double-ringed pyrimidines
8 StructureLabel the following parts of the DNA nucleotides below: adenine, thymine, guanine, cytosine, purines, pyrimidines, phosphate, and sugar
9 StructureNucleotides bond together to form a double stranded DNA moleculeDNA’s structure looks like a twisted ladderThis structure is called the double helixThe deoxyribose and phosphate form the “sidepieces,” of the ladder.Nitrogen bases bond together to form the “rungs,” of the ladder.
11 StructureLabel the following parts of the DNA molecule below: nucleotide, hydrogen bonds, sugar-phosphate backboneNucleotideSugar-phosphate backboneKeyAdenine (A)Thymine (T)Cytosine (C)Guanine (G)
12 Chargaff’s Base Pairing Rules Adenine always bonds to thymineCytosine always bonds to guanineThe nitrogen bases are bonded with weak hydrogen bondsWhy do only certain nitrogen bases bind to each other?
13 Chargaff’s Base Pairing Rules Complete the other half of the DNA molecule below using Chargaff’s base pairing rules:A T G A A C G T C A C C G T A C A T C G T
14 DNA and ChromosomesIn eukaryotic cells, DNA molecules are tightly wound into chromosomesWhere are chromosomes located in eukaryotic cells?Chromosomes contain all the DNA needed to carry out cellular functions
15 DNA and ChromosomesLabel the following parts of the diagram below: double helix, chromosome, supercoils, coils, histones, proteinsHistones