2. 1. DNA

4. DNA is a nucleic acid It consists on a long chain of molecules called nucleotides . The nucleotides are joined by a sugar - phosphate backbone. 4 nucleotides Differ in their nitrogenous bases Thymine (T) Cytosine (C) Adenine (A) Guanine (G) !

6. James WATSON and Francis CRICK determined that DNA is a double helix .

8. 2. DNA Replication

9. 2. DNA Replication When a cell or whole organism reproduces, a complete set of genetic instructions must pass from one generation to the next.

10. DNA is split in 2 strands and each strand is copied to form a new DNA molecule

11. DNA replication: - starts at specific sites ( origin of replication ) - goes in both directions

12. 3. From DNA to RNA to PROTEIN

13. From DNA to RNA to PROTEIN How an Organism’s Genotype Produces Its Phenotype GENOTYPE : is the Genetic Constitution of an organism or cell , its genetic make up . It is the sequence of nucleotide bases in DNA PHENOTYPE : is the organism’s specific traits , the organism’s total physical appearance and constitution. It is the result of the actions of proteins.

14. GENOTYPE: eye color gene called: bey2 PHENOTYPE: Example for phenotype and genotype

15. Nucleus Cytoplasm DNA specifies the synthesis of proteins in 2 stages : DNA Protein 2. TRANSLATION 1. TRANSCRIPTION RNA

16. TRANSCRIPTION : DNA  RNA TRANSLATION : RNA  PROTEIN From Nucleic Acid to Amino Acid Different Molecules - Different Languages 1 gene – 1 polypeptide hypothesis: The function of an individual gene dictates the production of a specific polypeptide.

19. The genetic code is shared by all organisms. GENETIC CODE: It is the set of rules relating nucleotide sequence to amino acid sequence.

20. Transcription: From DNA to RNA

22. Transcription done by RNA Polymerase which adds RNA nucleotide 1 by 1 to the newly made RNA sequence. The base of the nucleotide is complementary to the DNA base.

23. DNA Promoter Terminator RNA polymerase DNA of a gene RNA Initiation Elongation Completed RNA Single strand Termination

24. 1. INITIATION: The “start transcribing” signal is a nucleotide sequence called a promoter . The first phase of transcription is initiation: RNA polymerase attaches to the promoter. RNA synthesis begins. 2. ELONGATION: Second phase. The RNA gets longer. 3. TERMINATION: RNA polymerase reaches a sequence of DNA bases called a terminator . 3 PHASES OF TRANSCRIPTION

25. But RNA is not ready yet… It needs to be processed.

27. What does this mean? What are caps and tails? A cap and a tail are added at the extremities of the newly RNA molecule. It protects the RNA from enzymes; and help the ribosomes recognize it.

28. A gene contains EXONS and INTRONS What are EXONS and INTRONS? EXONS are kept and will be translated into polypeptides (EX for EXiting the nucleus) INTRONS are rid of. Exon Exon Exon Intron Intron

29. Remember… 1 gene – 1 polypeptide hypothesis: The function of an individual gene dictates the production of a specific polypeptide. ACTUALLY, it could be several….. 1 gene can give different versions of a protein. By combining (splicing) different exons.

30. DNA READY TO GO! Exon Exon Exon Intron Intron RNA Transcription Cap and Tail added Introns removed Splicing of exons Coding sequence

31. Translation: From RNA to PROTEIN From nucleic acid to amino acid

33. codons ribosome mRNA tRNA Growing polypeptide Next amino acid to be added Formation of a Protein aa

34. Translation: The Process Translation is divided into 3 phases: 1. Initiation 2. Elongation 3. Termination

37. 1. codon recognition codons Empty site New codon mRNA moves 2. peptide bond formation 3. translocation

38. 3. Termination Elongation continues until the ribosome reaches a stop codon and the polypeptide is released.

39. Review: DNA  RNA  Protein

40. 4. Mutations

41. A mutation is any change in the nucleotide sequence of DNA. Mutations