U3 AOS1 Topic 3: Nucleic Acids

Nucleic Acids (such as DNA and RNA) are polymers, composed of nucleotide monomers. They are information molecules which encode instructions for protein synthesis.
Nucleotide Structure includes a phosphate group, a five-carbon sugar, and a nitrogenous base (Adenine, Thymine, Guanine Cytosine, or Uracil)

Each of the five Carbon atoms in the sugar (aka Pentose) is assigned a number (1' to 5') in the clockwise direction
1' attaches to the Nitrogenous Base
5' attaches to the phosphate group of this nucleotide
3' attaches to a phosphate group of a neighboring nucleotide, forming a Phosphodiester bond (discussed later)

Nucleotides within the Nucleic are bound by a phosphodiester bond (Which is formed by condensation polymerisation between the sugar group and phosphate group)

This process is similar to laying a row of bricks, where: the individual nucleotides are bricks, the cement connecting them is the phosphodiester bond

Deoxyribonucleic Acid (DNA)
- Consists of 2 Strands of nucleotides bonded via complementary base pairing, forming a double helix
- This double helix runs in an antiparallel manner - as depicted in the image. One strand is oriented 5' to 3', whereas the other one runs from the 3' end to the 5' end.

Important facts:
- contains a deoxyribose sugar (Oxygen absent at Carbon 2') - important differentiator between DNA and RNA
- Found inside the nucleus of Eukaryotic cells
-Complete set of DNA = Genome
- A and T are bound by 2 Hydrogen bonds
- C and G are bound by 3 Hydrogen bonds

Ribonucleic Acid (RNA)
- Single Strand of Nucleotides that is fouind in various forms ------> Primarily involved in protein synthesis
- Messenger RNA (mRNA): carries genetic information from the nucleus to the ribosomes for protein synthesis
- Transfer RNA (tRNA): delivers specific amino acids to the ribosome after recognising specific nucleotide sequences on mRNA
- Ribosomal RNA (rRNA): serves as the main structural component of ribosomes within cells
Facts: contains ribose sugar,(Oxygen is present at Carbon 2'); no thymine, uracil instead (A-U, C-G, ionstead of A-T, C-G); temporary molecules

Example 1

Which bond binds nucleotides together to form a strand, and What type of reaction allows for the formation of this bond?

- The bond which binds individual nucleotides together in a strand of DNA is called the Phosphodiester bond

- A condensation polymerization reaction between the phosphate group and Sugar group of an adjacent nucleotide - in which energy is an inputted and water is produced* - forms this bond

*This step isn't necessary in this question, but it is good to get memorize the inputs and outputs of important catabolic and anabolic reactions for future question