Section12.2

 3. DNA (deoxyribonucleic acid) is a nucleic acid made up of nucleotides joined into long strands by covalent bonds

 3. Nucleotides are building blocks of nucleic acids  4. Nucleotides: 3 parts ▪ 5. 5-carbon sugar: deoxyribose ▪ 5. Phosphate group ▪ 5. Nitrogenous base ▪ 4. 4 Nitrogenous bases (contain Nitrogen):  5. Adenine  5. Guanine  5. Thymine  5. Cytosine

 3. Nucleotides joined by covalent bonds  4. Forms between sugar of one nucleotide and phosphate group of the next. 3. Nitrogenous bases 4. Stick out sideways from the nucleotide chain 4. Nucleotides can be joined together in a number of different ways 4. Any base sequence is possible 4. That’s what makes us so different! 4. Have a special chemical structure that is especially good at absorbing UV light

 1. What are the 3 components of a nucleotide?  2. What are the four nitrogenous bases?  3. Do you think excessive UV light could damage your DNA? How?

 3. Austrian-American biochemist  3. Discovered that % of:  4. Adenine [A]= Thymine [T]  4. Guanine[G]= Cytosine [C] P. 345 Analyzing data #1-4 (5 min.)

 3. Explains Chargaff’s rule  3. Antiparallel strands  4. DNA runs in opposite directions 3. Hydrogen bonds 4. Both strands of DNA are held together by H bonds between nitrogenous bases (A and T) and (G and C). 3. Base pairing 4. A always lines up perfectly with T 4. G always lines up perfectly with C

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