1.1 Building Blocks of DNA

• Where are genes located in a cell?

  In the cell nucleus
• What do genes control in the cell?

  Protein synthesis
• What type of molecules are DNA composed of?

  Double-stranded helical molecules
• What is the molecular weight of DNA measured in?

  Billions
• What are the basic chemical compounds in DNA?

  Phosphoric acid, deoxyribose, nitrogenous bases
• What forms the backbone of the DNA molecule?

  Phosphoric acid and deoxyribose
• How many nitrogenous bases are in DNA?

  Four
• What are the two types of nitrogenous bases in DNA?

  Purines and pyrimidines
• Name the two purines found in DNA.

  Adenine and guanine
• Name the two pyrimidines found in DNA.

  Thymine and cytosine
• What is formed when phosphoric acid, deoxyribose, and a base combine?

  An acidic nucleotide
• How many separate nucleotides are formed in DNA?

  Four
• What are the names of the four nucleotides in DNA?

  Deoxyadenylic, deoxythymidylic, deoxyguanylic, deoxycytidylic
• How are nucleotides organized in DNA?

  To form two strands loosely bound together
• What type of bonds hold the two DNA strands together?

  Weak cross-linkages
• What is the backbone of each DNA strand composed of?

  Alternating phosphoric acid and deoxyribose
• How do purine and pyrimidine bases connect in DNA?

  Through loose hydrogen bonds
• Which purine base bonds with thymine?

  Adenine
• Which purine base bonds with cytosine?

  Guanine
• What is the sequence of complementary pairs of bases in DNA?

  CG, CG, GC, TA, CG, TA, GC, AT, AT
• How many pairs of nucleotides are present in each full turn of the DNA helix?

  Ten pairs
• How can the two strands of DNA be separated?

  By pulling apart due to loose hydrogen bonds