1. From DNA to Protein Chapter 8

2. Terminology Genetics Genome Chromosome Gene Locus Alleles Genotype/Phenotype Heredity

3. Living cells must accomplish two general tasks to multiply and survive –DNA replication –Gene expression Expression involves two process –Transcription –Translation –Flow of information from DNA to RNA to protein

4. Polymer of nucleotides Hydrogen bonds between complementary bases –AT and CG Antiparallel New nucleotides can only be added to the “free” 3’ end DNA

5. DNA synthesis involves anabolic polymerization Monomers (Triphosphate deoxyribonucleotides) provide required energy for DNA synthesis

6. One DNA double helix. Semi-conservative DNA replication Two identical DNA double helixes, each with one parental strand (blue) and one new strand (pink). Replication produces two DNA double helixes Each contains one original strand and one new strand

7. DNA replication in bacteria is bi-directional –due to closed circular chromosome –replication forks eventually meet and two complete loops are separated

8. Bacterial DNA is attached at several points to the cell membrane –Enzymes need for replication are membrane proteins

9. Topoisomerase (DNA gyrase) Helicase Primase DNA polymerases DNA Ligase

10. Bacteria replication involves methylation of daughter stands –Methylase –Adds methyl group (-CH 3 ) to nitrogenous bases (typically adenine) Methylation functions: –Initiation of DNA repliction –Control of genetic expression –Protection from viral infection –Repair of DNA

11. DNA Replication As DNA unwinds, it creates a replication fork As nucleotides are added, the replication fork moves down the parental strand

12. –Leading strand Is synthesized CONTINUOUSLY as the DNA polymerase moves towards the replication fork –Lagging strand Is synthesized DISCONTINUOUSLY in pieces as DNA polymerase moves away from the replication fork Okazaki fragments

13. Single Strand Binding Proteins

14. DNA contains the instructions for protein synthesis –Genes RNA carries out the instructions Genetic information flows from DNA to RNA to protein

15. Central Dogma of Molecular Biology –DNA Transcribed RNA –RNA Translated Protein

17. Gene Expression Transcription –RNA polymerase synthesizes complementary mRNA from DNA template –Cytoplasm of prokaryotes and the nucleus of eukaryotes

18. Concurrent RNA transcription Multiple copies of RNA can be transcribed simultaneously

19. Eukaryotic DNA is more complex –Requires post- transcriptional modifications –Spliceosome –Cap and tail

20. Translation –The language of mRNA is in the form of codons Three nucleotides situated next to each other on DNA –Sequence of codons determines sequence of amino acids in the protein –64 codons make up the “alphabet” 61 are sense codons 3 “stop codons”

21. The site of translation is the ribosome

22. tRNA brings appropriate amino acid to site of translation Each tRNA has an anticodon –complementary sequence to the mRNA codon

26. In a prokaryotes, many molecules of mRNA can by transcribed simultaneously Why can translation begin before transcription is completed in a prokaryote but not in a eukaryote?

27. template DNA strand complementary DNA strand DNA gene codons anticodons amino acids mRNA tRNA methionineglycinevaline protein