1. Processes of Nucleic AcidsSeptember 17 & 18, 2012 DNA Synthesis (Replication) 1.Helicase – Separates parental DNA strands (unwind double helix) 2.ssB (single-stranded Binding) proteins – Prevents single strands from re-associating 3.RNA Primase – Synthesizes RNA primers, required to initiate DNA nucleotide insertion 4.DNA Polymerase III – Responsible for synthesis of lagging strand & leading strand 5.DNA Pol I – Removes RNA primers & Fills lagging strand gaps (Exonuclease Activity) 6.DNA Ligase – Forms Phosphodiester bond joining 2 adjacent DNA strands

2. Processes of Nucleic AcidsSeptember 17 & 18, 2012

5. rRNA (Ribosomal RNA) – in nucleolus gives rise to ribosomal precursors; makes Ribosome, and is the central component of the Ribosome’s protein-manufacturing machinery.

6. Processes of Nucleic AcidsSeptember 17 & 18, 2012 mRNA (Messenger RNA) - encodes chemical "blueprint" for protein (The Genetic Code); carries coding information from Nucleus to Ribosomes (sites of protein synthesis). Details of mRNA:  Encoded in sequence of nucleotides (AUCG), which are arranged into codons consisting of three bases each  Each codon encodes a specific amino acid, except the stop codons  Stop codons terminate protein synthesis

7. Processes of Nucleic AcidsSeptember 17 & 18, 2012 tRNA (Transfer RNA) - adaptor molecule composed of RNA used to bridge the genetic code (AUCG) in mRNA with the twenty amino-acids code in proteins. Details of tRNA:  The role of tRNA is to specify which sequence from the genetic code corresponds to which amino acid  One end of the tRNA complements the genetic code in a three- nucleotide sequence called the anticodon  On the other end of the tRNA is a covalent attachment to the amino acid that corresponds to the anticodon sequence  Each type of tRNA molecule can be attached to only one type of amino acid o The genetic code contains multiple codons that specify the same amino acid; therefore, there are many tRNA molecules, each bearing a different anticodon, which also carry the same amino acid.

8. Processes of Nucleic AcidsSeptember 17 & 18, 2012 *Baking a Cake Analogy

9. Processes of Nucleic AcidsSeptember 17 & 18, 2012

12. Translation *AUG (Methionine) – Start Codon*UAG, UGA, UAA – Stop Codons

13. Processes of Nucleic AcidsSeptember 17 & 18, 2012 Initiation:  Binding of mRNA to small ribosomal subunit containing tRNA i met  mRNA is scanned for AUG start codon  First amino acid is Methionine

14. Processes of Nucleic AcidsSeptember 17 & 18, 2012

15. Elongation:  Met-tRNA i already bound to (P) site 1.mRNA codon in (A) site determines which aminoacyl-tRNA binds to (A) site 2.Methionine binds (peptide bond) to aminoacyl 1 at (A) site 3.Methionine & aminoacyl 1 translocate to (A) site, which now is (P) site – freeing (A) site for a new aminoacyl-tRNA  Steps 1-3 repeat until termination

16. Processes of Nucleic AcidsSeptember 17 & 18, 2012

17. Termination:  A termination (stop) codon is placed into the (A) site on the ribosome a)UAG, UGA, UAA b)There are NO tRNA anticodons that bind Stop Codons  Release Factors (RF) bind to ribosome  Newly peptide chain is released from ribosome

18. Processes of Nucleic AcidsSeptember 17 & 18, 2012