3.1.5a - Structure of DNA and RNA | 3.1.6 - ATP

Thursday 9th November ‘23

• Structure

  • DNA and RNA are nucleotides consisting of a pentose sugar attached to a phosphate group and a nitrogen-containing base. These form the building blocks for nucleic acids.

  • ATP is a nucleotide derivative and is formed from a molecule of ribose (pentose sugar), a molecule of adenine (nitrogen containing base) and 3 phosphate groups.

• Function

  • DNA is the molecule that holds the genetic information for the development and functioning of an organism and is found in the nucleus.

  • RNA transfers the genetic information from the DNA in the nucleus to the ribosomes for protein synthesis.

  • ATP is broken down to release energy; it is reformed (to store energy) easily and quickly by either removing or regaining a phosphate group.

    • Hydrolysis of ATP to ADP + Pi - this is catalysed by the enzyme ATP hydrolase - energy to release - phosphate group can be used to phosphorylate other compounds usually to make them more reactive.

    • Condensation of ADP + Pi to ATP - this is catalysed by the enzyme ATP synthase during processes such as photosynthesis and respiration.

• Bondings

  • In DNA, phosphodiester bonds link nucleotides. This is between the phosphate group and a carbon in the pentose sugar of another.

  • In DNA and RNA, ester bonds link deoxyribose sugar and phosphate

  • In DNA and RNA, glycosidic bonds link deoxyribose sugar and base

  • In RNA, a phosphodiester bond is formed between the phosphate group of 1 nucleotide and a carbon in the pentose sugar of another

• What does it look like?

  • RNA is a single, relatively short polynuclotide chain.

  • DNA molecule is made up of 2 polynucleotide chains held together by hydrogen bonds to form a double helix.

• Bases

  • DNA: Adenine and Thymine form 2 hydrogen bonds; Cytesine and Guanine form 3 hydrogen bonds.

  • Adenine and Uracil; Cytesine and Guanine